Import vim from changeset v5628:c9cad40b4181

- Cleanup source tree, leaving only files necessary for compilation/testing
- Process files through unifdef to remove tons of FEAT_* macros
- Process files through uncrustify to normalize source code formatting.
- Port the build system to cmake

1 files changed, 2296 insertions, 0 deletions

diff --git a/src/diff.c b/src/diff.c
new file mode 100644
index 0000000000..ad31128575
--- /dev/null
+++ b/src/diff.c
@@ -0,0 +1,2296 @@
+/* vim:set ts=8 sts=4 sw=4:
+ *
+ * VIM - Vi IMproved	by Bram Moolenaar
+ *
+ * Do ":help uganda"  in Vim to read copying and usage conditions.
+ * Do ":help credits" in Vim to see a list of people who contributed.
+ * See README.txt for an overview of the Vim source code.
+ */
+
+/*
+ * diff.c: code for diff'ing two, three or four buffers.
+ */
+
+#include "vim.h"
+
+
+static int diff_busy = FALSE;           /* ex_diffgetput() is busy */
+
+/* flags obtained from the 'diffopt' option */
+#define DIFF_FILLER     1       /* display filler lines */
+#define DIFF_ICASE      2       /* ignore case */
+#define DIFF_IWHITE     4       /* ignore change in white space */
+#define DIFF_HORIZONTAL 8       /* horizontal splits */
+#define DIFF_VERTICAL   16      /* vertical splits */
+static int diff_flags = DIFF_FILLER;
+
+#define LBUFLEN 50              /* length of line in diff file */
+
+static int diff_a_works = MAYBE; /* TRUE when "diff -a" works, FALSE when it
+                                    doesn't work, MAYBE when not checked yet */
+
+static int diff_buf_idx __ARGS((buf_T *buf));
+static int diff_buf_idx_tp __ARGS((buf_T *buf, tabpage_T *tp));
+static void diff_mark_adjust_tp __ARGS((tabpage_T *tp, int idx, linenr_T line1,
+                                        linenr_T line2, long amount,
+                                        long amount_after));
+static void diff_check_unchanged __ARGS((tabpage_T *tp, diff_T *dp));
+static int diff_check_sanity __ARGS((tabpage_T *tp, diff_T *dp));
+static void diff_redraw __ARGS((int dofold));
+static int diff_write __ARGS((buf_T *buf, char_u *fname));
+static void diff_file __ARGS((char_u *tmp_orig, char_u *tmp_new,
+                              char_u *tmp_diff));
+static int diff_equal_entry __ARGS((diff_T *dp, int idx1, int idx2));
+static int diff_cmp __ARGS((char_u *s1, char_u *s2));
+static void diff_fold_update __ARGS((diff_T *dp, int skip_idx));
+static void diff_read __ARGS((int idx_orig, int idx_new, char_u *fname));
+static void diff_copy_entry __ARGS((diff_T *dprev, diff_T *dp, int idx_orig,
+                                    int idx_new));
+static diff_T *diff_alloc_new __ARGS((tabpage_T *tp, diff_T *dprev, diff_T *dp));
+
+#ifndef USE_CR
+# define tag_fgets vim_fgets
+#endif
+
+/*
+ * Called when deleting or unloading a buffer: No longer make a diff with it.
+ */
+void diff_buf_delete(buf)
+buf_T       *buf;
+{
+  int i;
+  tabpage_T   *tp;
+
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+    i = diff_buf_idx_tp(buf, tp);
+    if (i != DB_COUNT) {
+      tp->tp_diffbuf[i] = NULL;
+      tp->tp_diff_invalid = TRUE;
+      if (tp == curtab)
+        diff_redraw(TRUE);
+    }
+  }
+}
+
+/*
+ * Check if the current buffer should be added to or removed from the list of
+ * diff buffers.
+ */
+void diff_buf_adjust(win)
+win_T       *win;
+{
+  win_T       *wp;
+  int i;
+
+  if (!win->w_p_diff) {
+    /* When there is no window showing a diff for this buffer, remove
+     * it from the diffs. */
+    for (wp = firstwin; wp != NULL; wp = wp->w_next)
+      if (wp->w_buffer == win->w_buffer && wp->w_p_diff)
+        break;
+    if (wp == NULL) {
+      i = diff_buf_idx(win->w_buffer);
+      if (i != DB_COUNT) {
+        curtab->tp_diffbuf[i] = NULL;
+        curtab->tp_diff_invalid = TRUE;
+        diff_redraw(TRUE);
+      }
+    }
+  } else
+    diff_buf_add(win->w_buffer);
+}
+
+/*
+ * Add a buffer to make diffs for.
+ * Call this when a new buffer is being edited in the current window where
+ * 'diff' is set.
+ * Marks the current buffer as being part of the diff and requiring updating.
+ * This must be done before any autocmd, because a command may use info
+ * about the screen contents.
+ */
+void diff_buf_add(buf)
+buf_T       *buf;
+{
+  int i;
+
+  if (diff_buf_idx(buf) != DB_COUNT)
+    return;             /* It's already there. */
+
+  for (i = 0; i < DB_COUNT; ++i)
+    if (curtab->tp_diffbuf[i] == NULL) {
+      curtab->tp_diffbuf[i] = buf;
+      curtab->tp_diff_invalid = TRUE;
+      diff_redraw(TRUE);
+      return;
+    }
+
+  EMSGN(_("E96: Can not diff more than %ld buffers"), DB_COUNT);
+}
+
+/*
+ * Find buffer "buf" in the list of diff buffers for the current tab page.
+ * Return its index or DB_COUNT if not found.
+ */
+static int diff_buf_idx(buf)
+buf_T       *buf;
+{
+  int idx;
+
+  for (idx = 0; idx < DB_COUNT; ++idx)
+    if (curtab->tp_diffbuf[idx] == buf)
+      break;
+  return idx;
+}
+
+/*
+ * Find buffer "buf" in the list of diff buffers for tab page "tp".
+ * Return its index or DB_COUNT if not found.
+ */
+static int diff_buf_idx_tp(buf, tp)
+buf_T       *buf;
+tabpage_T   *tp;
+{
+  int idx;
+
+  for (idx = 0; idx < DB_COUNT; ++idx)
+    if (tp->tp_diffbuf[idx] == buf)
+      break;
+  return idx;
+}
+
+/*
+ * Mark the diff info involving buffer "buf" as invalid, it will be updated
+ * when info is requested.
+ */
+void diff_invalidate(buf)
+buf_T       *buf;
+{
+  tabpage_T   *tp;
+  int i;
+
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+    i = diff_buf_idx_tp(buf, tp);
+    if (i != DB_COUNT) {
+      tp->tp_diff_invalid = TRUE;
+      if (tp == curtab)
+        diff_redraw(TRUE);
+    }
+  }
+}
+
+/*
+ * Called by mark_adjust(): update line numbers in "curbuf".
+ */
+void diff_mark_adjust(line1, line2, amount, amount_after)
+linenr_T line1;
+linenr_T line2;
+long amount;
+long amount_after;
+{
+  int idx;
+  tabpage_T   *tp;
+
+  /* Handle all tab pages that use the current buffer in a diff. */
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+    idx = diff_buf_idx_tp(curbuf, tp);
+    if (idx != DB_COUNT)
+      diff_mark_adjust_tp(tp, idx, line1, line2, amount, amount_after);
+  }
+}
+
+/*
+ * Update line numbers in tab page "tp" for "curbuf" with index "idx".
+ * This attempts to update the changes as much as possible:
+ * When inserting/deleting lines outside of existing change blocks, create a
+ * new change block and update the line numbers in following blocks.
+ * When inserting/deleting lines in existing change blocks, update them.
+ */
+static void diff_mark_adjust_tp(tp, idx, line1, line2, amount, amount_after)
+tabpage_T   *tp;
+int idx;
+linenr_T line1;
+linenr_T line2;
+long amount;
+long amount_after;
+{
+  diff_T      *dp;
+  diff_T      *dprev;
+  diff_T      *dnext;
+  int i;
+  int inserted, deleted;
+  int n, off;
+  linenr_T last;
+  linenr_T lnum_deleted = line1;        /* lnum of remaining deletion */
+  int check_unchanged;
+
+  if (line2 == MAXLNUM) {
+    /* mark_adjust(99, MAXLNUM, 9, 0): insert lines */
+    inserted = amount;
+    deleted = 0;
+  } else if (amount_after > 0)   {
+    /* mark_adjust(99, 98, MAXLNUM, 9): a change that inserts lines*/
+    inserted = amount_after;
+    deleted = 0;
+  } else   {
+    /* mark_adjust(98, 99, MAXLNUM, -2): delete lines */
+    inserted = 0;
+    deleted = -amount_after;
+  }
+
+  dprev = NULL;
+  dp = tp->tp_first_diff;
+  for (;; ) {
+    /* If the change is after the previous diff block and before the next
+     * diff block, thus not touching an existing change, create a new diff
+     * block.  Don't do this when ex_diffgetput() is busy. */
+    if ((dp == NULL || dp->df_lnum[idx] - 1 > line2
+         || (line2 == MAXLNUM && dp->df_lnum[idx] > line1))
+        && (dprev == NULL
+            || dprev->df_lnum[idx] + dprev->df_count[idx] < line1)
+        && !diff_busy) {
+      dnext = diff_alloc_new(tp, dprev, dp);
+      if (dnext == NULL)
+        return;
+
+      dnext->df_lnum[idx] = line1;
+      dnext->df_count[idx] = inserted;
+      for (i = 0; i < DB_COUNT; ++i)
+        if (tp->tp_diffbuf[i] != NULL && i != idx) {
+          if (dprev == NULL)
+            dnext->df_lnum[i] = line1;
+          else
+            dnext->df_lnum[i] = line1
+                                + (dprev->df_lnum[i] + dprev->df_count[i])
+                                - (dprev->df_lnum[idx] + dprev->df_count[idx]);
+          dnext->df_count[i] = deleted;
+        }
+    }
+
+    /* if at end of the list, quit */
+    if (dp == NULL)
+      break;
+
+    /*
+     * Check for these situations:
+     *	  1  2	3
+     *	  1  2	3
+     * line1     2	3  4  5
+     *	     2	3  4  5
+     *	     2	3  4  5
+     * line2     2	3  4  5
+     *		3     5  6
+     *		3     5  6
+     */
+    /* compute last line of this change */
+    last = dp->df_lnum[idx] + dp->df_count[idx] - 1;
+
+    /* 1. change completely above line1: nothing to do */
+    if (last >= line1 - 1) {
+      /* 6. change below line2: only adjust for amount_after; also when
+       * "deleted" became zero when deleted all lines between two diffs */
+      if (dp->df_lnum[idx] - (deleted + inserted != 0) > line2) {
+        if (amount_after == 0)
+          break;                /* nothing left to change */
+        dp->df_lnum[idx] += amount_after;
+      } else   {
+        check_unchanged = FALSE;
+
+        /* 2. 3. 4. 5.: inserted/deleted lines touching this diff. */
+        if (deleted > 0) {
+          if (dp->df_lnum[idx] >= line1) {
+            off = dp->df_lnum[idx] - lnum_deleted;
+            if (last <= line2) {
+              /* 4. delete all lines of diff */
+              if (dp->df_next != NULL
+                  && dp->df_next->df_lnum[idx] - 1 <= line2) {
+                /* delete continues in next diff, only do
+                 * lines until that one */
+                n = dp->df_next->df_lnum[idx] - lnum_deleted;
+                deleted -= n;
+                n -= dp->df_count[idx];
+                lnum_deleted = dp->df_next->df_lnum[idx];
+              } else
+                n = deleted - dp->df_count[idx];
+              dp->df_count[idx] = 0;
+            } else   {
+              /* 5. delete lines at or just before top of diff */
+              n = off;
+              dp->df_count[idx] -= line2 - dp->df_lnum[idx] + 1;
+              check_unchanged = TRUE;
+            }
+            dp->df_lnum[idx] = line1;
+          } else   {
+            off = 0;
+            if (last < line2) {
+              /* 2. delete at end of of diff */
+              dp->df_count[idx] -= last - lnum_deleted + 1;
+              if (dp->df_next != NULL
+                  && dp->df_next->df_lnum[idx] - 1 <= line2) {
+                /* delete continues in next diff, only do
+                 * lines until that one */
+                n = dp->df_next->df_lnum[idx] - 1 - last;
+                deleted -= dp->df_next->df_lnum[idx]
+                           - lnum_deleted;
+                lnum_deleted = dp->df_next->df_lnum[idx];
+              } else
+                n = line2 - last;
+              check_unchanged = TRUE;
+            } else   {
+              /* 3. delete lines inside the diff */
+              n = 0;
+              dp->df_count[idx] -= deleted;
+            }
+          }
+
+          for (i = 0; i < DB_COUNT; ++i)
+            if (tp->tp_diffbuf[i] != NULL && i != idx) {
+              dp->df_lnum[i] -= off;
+              dp->df_count[i] += n;
+            }
+        } else   {
+          if (dp->df_lnum[idx] <= line1) {
+            /* inserted lines somewhere in this diff */
+            dp->df_count[idx] += inserted;
+            check_unchanged = TRUE;
+          } else
+            /* inserted lines somewhere above this diff */
+            dp->df_lnum[idx] += inserted;
+        }
+
+        if (check_unchanged)
+          /* Check if inserted lines are equal, may reduce the
+           * size of the diff.  TODO: also check for equal lines
+           * in the middle and perhaps split the block. */
+          diff_check_unchanged(tp, dp);
+      }
+    }
+
+    /* check if this block touches the previous one, may merge them. */
+    if (dprev != NULL && dprev->df_lnum[idx] + dprev->df_count[idx]
+        == dp->df_lnum[idx]) {
+      for (i = 0; i < DB_COUNT; ++i)
+        if (tp->tp_diffbuf[i] != NULL)
+          dprev->df_count[i] += dp->df_count[i];
+      dprev->df_next = dp->df_next;
+      vim_free(dp);
+      dp = dprev->df_next;
+    } else   {
+      /* Advance to next entry. */
+      dprev = dp;
+      dp = dp->df_next;
+    }
+  }
+
+  dprev = NULL;
+  dp = tp->tp_first_diff;
+  while (dp != NULL) {
+    /* All counts are zero, remove this entry. */
+    for (i = 0; i < DB_COUNT; ++i)
+      if (tp->tp_diffbuf[i] != NULL && dp->df_count[i] != 0)
+        break;
+    if (i == DB_COUNT) {
+      dnext = dp->df_next;
+      vim_free(dp);
+      dp = dnext;
+      if (dprev == NULL)
+        tp->tp_first_diff = dnext;
+      else
+        dprev->df_next = dnext;
+    } else   {
+      /* Advance to next entry. */
+      dprev = dp;
+      dp = dp->df_next;
+    }
+
+  }
+
+  if (tp == curtab) {
+    diff_redraw(TRUE);
+
+    /* Need to recompute the scroll binding, may remove or add filler
+     * lines (e.g., when adding lines above w_topline). But it's slow when
+     * making many changes, postpone until redrawing. */
+    diff_need_scrollbind = TRUE;
+  }
+}
+
+/*
+ * Allocate a new diff block and link it between "dprev" and "dp".
+ */
+static diff_T * diff_alloc_new(tp, dprev, dp)
+tabpage_T   *tp;
+diff_T      *dprev;
+diff_T      *dp;
+{
+  diff_T      *dnew;
+
+  dnew = (diff_T *)alloc((unsigned)sizeof(diff_T));
+  if (dnew != NULL) {
+    dnew->df_next = dp;
+    if (dprev == NULL)
+      tp->tp_first_diff = dnew;
+    else
+      dprev->df_next = dnew;
+  }
+  return dnew;
+}
+
+/*
+ * Check if the diff block "dp" can be made smaller for lines at the start and
+ * end that are equal.  Called after inserting lines.
+ * This may result in a change where all buffers have zero lines, the caller
+ * must take care of removing it.
+ */
+static void diff_check_unchanged(tp, dp)
+tabpage_T   *tp;
+diff_T      *dp;
+{
+  int i_org;
+  int i_new;
+  int off_org, off_new;
+  char_u      *line_org;
+  int dir = FORWARD;
+
+  /* Find the first buffers, use it as the original, compare the other
+   * buffer lines against this one. */
+  for (i_org = 0; i_org < DB_COUNT; ++i_org)
+    if (tp->tp_diffbuf[i_org] != NULL)
+      break;
+  if (i_org == DB_COUNT)        /* safety check */
+    return;
+
+  if (diff_check_sanity(tp, dp) == FAIL)
+    return;
+
+  /* First check lines at the top, then at the bottom. */
+  off_org = 0;
+  off_new = 0;
+  for (;; ) {
+    /* Repeat until a line is found which is different or the number of
+     * lines has become zero. */
+    while (dp->df_count[i_org] > 0) {
+      /* Copy the line, the next ml_get() will invalidate it.  */
+      if (dir == BACKWARD)
+        off_org = dp->df_count[i_org] - 1;
+      line_org = vim_strsave(ml_get_buf(tp->tp_diffbuf[i_org],
+              dp->df_lnum[i_org] + off_org, FALSE));
+      if (line_org == NULL)
+        return;
+      for (i_new = i_org + 1; i_new < DB_COUNT; ++i_new) {
+        if (tp->tp_diffbuf[i_new] == NULL)
+          continue;
+        if (dir == BACKWARD)
+          off_new = dp->df_count[i_new] - 1;
+        /* if other buffer doesn't have this line, it was inserted */
+        if (off_new < 0 || off_new >= dp->df_count[i_new])
+          break;
+        if (diff_cmp(line_org, ml_get_buf(tp->tp_diffbuf[i_new],
+                    dp->df_lnum[i_new] + off_new, FALSE)) != 0)
+          break;
+      }
+      vim_free(line_org);
+
+      /* Stop when a line isn't equal in all diff buffers. */
+      if (i_new != DB_COUNT)
+        break;
+
+      /* Line matched in all buffers, remove it from the diff. */
+      for (i_new = i_org; i_new < DB_COUNT; ++i_new)
+        if (tp->tp_diffbuf[i_new] != NULL) {
+          if (dir == FORWARD)
+            ++dp->df_lnum[i_new];
+          --dp->df_count[i_new];
+        }
+    }
+    if (dir == BACKWARD)
+      break;
+    dir = BACKWARD;
+  }
+}
+
+/*
+ * Check if a diff block doesn't contain invalid line numbers.
+ * This can happen when the diff program returns invalid results.
+ */
+static int diff_check_sanity(tp, dp)
+tabpage_T   *tp;
+diff_T      *dp;
+{
+  int i;
+
+  for (i = 0; i < DB_COUNT; ++i)
+    if (tp->tp_diffbuf[i] != NULL)
+      if (dp->df_lnum[i] + dp->df_count[i] - 1
+          > tp->tp_diffbuf[i]->b_ml.ml_line_count)
+        return FAIL;
+  return OK;
+}
+
+/*
+ * Mark all diff buffers in the current tab page for redraw.
+ */
+static void diff_redraw(dofold)
+int dofold;                 /* also recompute the folds */
+{
+  win_T       *wp;
+  int n;
+
+  for (wp = firstwin; wp != NULL; wp = wp->w_next)
+    if (wp->w_p_diff) {
+      redraw_win_later(wp, SOME_VALID);
+      if (dofold && foldmethodIsDiff(wp))
+        foldUpdateAll(wp);
+      /* A change may have made filler lines invalid, need to take care
+       * of that for other windows. */
+      n = diff_check(wp, wp->w_topline);
+      if ((wp != curwin && wp->w_topfill > 0) || n > 0) {
+        if (wp->w_topfill > n)
+          wp->w_topfill = (n < 0 ? 0 : n);
+        else if (n > 0 && n > wp->w_topfill)
+          wp->w_topfill = n;
+      }
+    }
+}
+
+/*
+ * Write buffer "buf" to file "name".
+ * Always use 'fileformat' set to "unix".
+ * Return FAIL for failure
+ */
+static int diff_write(buf, fname)
+buf_T       *buf;
+char_u      *fname;
+{
+  int r;
+  char_u      *save_ff;
+
+  save_ff = buf->b_p_ff;
+  buf->b_p_ff = vim_strsave((char_u *)FF_UNIX);
+  r = buf_write(buf, fname, NULL, (linenr_T)1, buf->b_ml.ml_line_count,
+      NULL, FALSE, FALSE, FALSE, TRUE);
+  free_string_option(buf->b_p_ff);
+  buf->b_p_ff = save_ff;
+  return r;
+}
+
+/*
+ * Completely update the diffs for the buffers involved.
+ * This uses the ordinary "diff" command.
+ * The buffers are written to a file, also for unmodified buffers (the file
+ * could have been produced by autocommands, e.g. the netrw plugin).
+ */
+void ex_diffupdate(eap)
+exarg_T     *eap UNUSED;            /* can be NULL */
+{
+  buf_T       *buf;
+  int idx_orig;
+  int idx_new;
+  char_u      *tmp_orig;
+  char_u      *tmp_new;
+  char_u      *tmp_diff;
+  FILE        *fd;
+  int ok;
+  int io_error = FALSE;
+
+  /* Delete all diffblocks. */
+  diff_clear(curtab);
+  curtab->tp_diff_invalid = FALSE;
+
+  /* Use the first buffer as the original text. */
+  for (idx_orig = 0; idx_orig < DB_COUNT; ++idx_orig)
+    if (curtab->tp_diffbuf[idx_orig] != NULL)
+      break;
+  if (idx_orig == DB_COUNT)
+    return;
+
+  /* Only need to do something when there is another buffer. */
+  for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new)
+    if (curtab->tp_diffbuf[idx_new] != NULL)
+      break;
+  if (idx_new == DB_COUNT)
+    return;
+
+  /* We need three temp file names. */
+  tmp_orig = vim_tempname('o');
+  tmp_new = vim_tempname('n');
+  tmp_diff = vim_tempname('d');
+  if (tmp_orig == NULL || tmp_new == NULL || tmp_diff == NULL)
+    goto theend;
+
+  /*
+   * Do a quick test if "diff" really works.  Otherwise it looks like there
+   * are no differences.  Can't use the return value, it's non-zero when
+   * there are differences.
+   * May try twice, first with "-a" and then without.
+   */
+  for (;; ) {
+    ok = FALSE;
+    fd = mch_fopen((char *)tmp_orig, "w");
+    if (fd == NULL)
+      io_error = TRUE;
+    else {
+      if (fwrite("line1\n", (size_t)6, (size_t)1, fd) != 1)
+        io_error = TRUE;
+      fclose(fd);
+      fd = mch_fopen((char *)tmp_new, "w");
+      if (fd == NULL)
+        io_error = TRUE;
+      else {
+        if (fwrite("line2\n", (size_t)6, (size_t)1, fd) != 1)
+          io_error = TRUE;
+        fclose(fd);
+        diff_file(tmp_orig, tmp_new, tmp_diff);
+        fd = mch_fopen((char *)tmp_diff, "r");
+        if (fd == NULL)
+          io_error = TRUE;
+        else {
+          char_u linebuf[LBUFLEN];
+
+          for (;; ) {
+            /* There must be a line that contains "1c1". */
+            if (tag_fgets(linebuf, LBUFLEN, fd))
+              break;
+            if (STRNCMP(linebuf, "1c1", 3) == 0)
+              ok = TRUE;
+          }
+          fclose(fd);
+        }
+        mch_remove(tmp_diff);
+        mch_remove(tmp_new);
+      }
+      mch_remove(tmp_orig);
+    }
+
+    /* When using 'diffexpr' break here. */
+    if (*p_dex != NUL)
+      break;
+
+
+    /* If we checked if "-a" works already, break here. */
+    if (diff_a_works != MAYBE)
+      break;
+    diff_a_works = ok;
+
+    /* If "-a" works break here, otherwise retry without "-a". */
+    if (ok)
+      break;
+  }
+  if (!ok) {
+    if (io_error)
+      EMSG(_("E810: Cannot read or write temp files"));
+    EMSG(_("E97: Cannot create diffs"));
+    diff_a_works = MAYBE;
+    goto theend;
+  }
+
+  /* :diffupdate! */
+  if (eap != NULL && eap->forceit)
+    for (idx_new = idx_orig; idx_new < DB_COUNT; ++idx_new) {
+      buf = curtab->tp_diffbuf[idx_new];
+      if (buf_valid(buf))
+        buf_check_timestamp(buf, FALSE);
+    }
+
+  /* Write the first buffer to a tempfile. */
+  buf = curtab->tp_diffbuf[idx_orig];
+  if (diff_write(buf, tmp_orig) == FAIL)
+    goto theend;
+
+  /* Make a difference between the first buffer and every other. */
+  for (idx_new = idx_orig + 1; idx_new < DB_COUNT; ++idx_new) {
+    buf = curtab->tp_diffbuf[idx_new];
+    if (buf == NULL)
+      continue;
+    if (diff_write(buf, tmp_new) == FAIL)
+      continue;
+    diff_file(tmp_orig, tmp_new, tmp_diff);
+
+    /* Read the diff output and add each entry to the diff list. */
+    diff_read(idx_orig, idx_new, tmp_diff);
+    mch_remove(tmp_diff);
+    mch_remove(tmp_new);
+  }
+  mch_remove(tmp_orig);
+
+  /* force updating cursor position on screen */
+  curwin->w_valid_cursor.lnum = 0;
+
+  diff_redraw(TRUE);
+
+theend:
+  vim_free(tmp_orig);
+  vim_free(tmp_new);
+  vim_free(tmp_diff);
+}
+
+/*
+ * Make a diff between files "tmp_orig" and "tmp_new", results in "tmp_diff".
+ */
+static void diff_file(tmp_orig, tmp_new, tmp_diff)
+char_u      *tmp_orig;
+char_u      *tmp_new;
+char_u      *tmp_diff;
+{
+  char_u      *cmd;
+  size_t len;
+
+  if (*p_dex != NUL)
+    /* Use 'diffexpr' to generate the diff file. */
+    eval_diff(tmp_orig, tmp_new, tmp_diff);
+  else {
+    len = STRLEN(tmp_orig) + STRLEN(tmp_new)
+          + STRLEN(tmp_diff) + STRLEN(p_srr) + 27;
+    cmd = alloc((unsigned)len);
+    if (cmd != NULL) {
+      /* We don't want $DIFF_OPTIONS to get in the way. */
+      if (getenv("DIFF_OPTIONS"))
+        vim_setenv((char_u *)"DIFF_OPTIONS", (char_u *)"");
+
+      /* Build the diff command and execute it.  Always use -a, binary
+       * differences are of no use.  Ignore errors, diff returns
+       * non-zero when differences have been found. */
+      vim_snprintf((char *)cmd, len, "diff %s%s%s%s%s %s",
+          diff_a_works == FALSE ? "" : "-a ",
+          "",
+          (diff_flags & DIFF_IWHITE) ? "-b " : "",
+          (diff_flags & DIFF_ICASE) ? "-i " : "",
+          tmp_orig, tmp_new);
+      append_redir(cmd, (int)len, p_srr, tmp_diff);
+      block_autocmds();         /* Avoid ShellCmdPost stuff */
+      (void)call_shell(cmd, SHELL_FILTER|SHELL_SILENT|SHELL_DOOUT);
+      unblock_autocmds();
+      vim_free(cmd);
+    }
+  }
+}
+
+/*
+ * Create a new version of a file from the current buffer and a diff file.
+ * The buffer is written to a file, also for unmodified buffers (the file
+ * could have been produced by autocommands, e.g. the netrw plugin).
+ */
+void ex_diffpatch(eap)
+exarg_T     *eap;
+{
+  char_u      *tmp_orig;        /* name of original temp file */
+  char_u      *tmp_new;         /* name of patched temp file */
+  char_u      *buf = NULL;
+  size_t buflen;
+  win_T       *old_curwin = curwin;
+  char_u      *newname = NULL;          /* name of patched file buffer */
+#ifdef UNIX
+  char_u dirbuf[MAXPATHL];
+  char_u      *fullname = NULL;
+#endif
+  struct stat st;
+
+
+  /* We need two temp file names. */
+  tmp_orig = vim_tempname('o');
+  tmp_new = vim_tempname('n');
+  if (tmp_orig == NULL || tmp_new == NULL)
+    goto theend;
+
+  /* Write the current buffer to "tmp_orig". */
+  if (buf_write(curbuf, tmp_orig, NULL,
+          (linenr_T)1, curbuf->b_ml.ml_line_count,
+          NULL, FALSE, FALSE, FALSE, TRUE) == FAIL)
+    goto theend;
+
+#ifdef UNIX
+  /* Get the absolute path of the patchfile, changing directory below. */
+  fullname = FullName_save(eap->arg, FALSE);
+#endif
+  buflen = STRLEN(tmp_orig) + (
+# ifdef UNIX
+    fullname != NULL ? STRLEN(fullname) :
+# endif
+    STRLEN(eap->arg)) + STRLEN(tmp_new) + 16;
+  buf = alloc((unsigned)buflen);
+  if (buf == NULL)
+    goto theend;
+
+#ifdef UNIX
+  /* Temporarily chdir to /tmp, to avoid patching files in the current
+   * directory when the patch file contains more than one patch.  When we
+   * have our own temp dir use that instead, it will be cleaned up when we
+   * exit (any .rej files created).  Don't change directory if we can't
+   * return to the current. */
+  if (mch_dirname(dirbuf, MAXPATHL) != OK || mch_chdir((char *)dirbuf) != 0)
+    dirbuf[0] = NUL;
+  else {
+# ifdef TEMPDIRNAMES
+    if (vim_tempdir != NULL)
+      ignored = mch_chdir((char *)vim_tempdir);
+    else
+# endif
+    ignored = mch_chdir("/tmp");
+    shorten_fnames(TRUE);
+  }
+#endif
+
+  if (*p_pex != NUL)
+    /* Use 'patchexpr' to generate the new file. */
+    eval_patch(tmp_orig,
+# ifdef UNIX
+        fullname != NULL ? fullname :
+# endif
+        eap->arg, tmp_new);
+  else {
+    /* Build the patch command and execute it.  Ignore errors.  Switch to
+     * cooked mode to allow the user to respond to prompts. */
+    vim_snprintf((char *)buf, buflen, "patch -o %s %s < \"%s\"",
+        tmp_new, tmp_orig,
+# ifdef UNIX
+        fullname != NULL ? fullname :
+# endif
+        eap->arg);
+    block_autocmds();           /* Avoid ShellCmdPost stuff */
+    (void)call_shell(buf, SHELL_FILTER | SHELL_COOKED);
+    unblock_autocmds();
+  }
+
+#ifdef UNIX
+  if (dirbuf[0] != NUL) {
+    if (mch_chdir((char *)dirbuf) != 0)
+      EMSG(_(e_prev_dir));
+    shorten_fnames(TRUE);
+  }
+#endif
+
+  /* patch probably has written over the screen */
+  redraw_later(CLEAR);
+
+  /* Delete any .orig or .rej file created. */
+  STRCPY(buf, tmp_new);
+  STRCAT(buf, ".orig");
+  mch_remove(buf);
+  STRCPY(buf, tmp_new);
+  STRCAT(buf, ".rej");
+  mch_remove(buf);
+
+  /* Only continue if the output file was created. */
+  if (mch_stat((char *)tmp_new, &st) < 0 || st.st_size == 0)
+    EMSG(_("E816: Cannot read patch output"));
+  else {
+    if (curbuf->b_fname != NULL) {
+      newname = vim_strnsave(curbuf->b_fname,
+          (int)(STRLEN(curbuf->b_fname) + 4));
+      if (newname != NULL)
+        STRCAT(newname, ".new");
+    }
+
+    /* don't use a new tab page, each tab page has its own diffs */
+    cmdmod.tab = 0;
+
+    if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL) {
+      /* Pretend it was a ":split fname" command */
+      eap->cmdidx = CMD_split;
+      eap->arg = tmp_new;
+      do_exedit(eap, old_curwin);
+
+      /* check that split worked and editing tmp_new */
+      if (curwin != old_curwin && win_valid(old_curwin)) {
+        /* Set 'diff', 'scrollbind' on and 'wrap' off. */
+        diff_win_options(curwin, TRUE);
+        diff_win_options(old_curwin, TRUE);
+
+        if (newname != NULL) {
+          /* do a ":file filename.new" on the patched buffer */
+          eap->arg = newname;
+          ex_file(eap);
+
+          /* Do filetype detection with the new name. */
+          if (au_has_group((char_u *)"filetypedetect"))
+            do_cmdline_cmd((char_u *)":doau filetypedetect BufRead");
+        }
+      }
+    }
+  }
+
+theend:
+  if (tmp_orig != NULL)
+    mch_remove(tmp_orig);
+  vim_free(tmp_orig);
+  if (tmp_new != NULL)
+    mch_remove(tmp_new);
+  vim_free(tmp_new);
+  vim_free(newname);
+  vim_free(buf);
+#ifdef UNIX
+  vim_free(fullname);
+#endif
+}
+
+/*
+ * Split the window and edit another file, setting options to show the diffs.
+ */
+void ex_diffsplit(eap)
+exarg_T     *eap;
+{
+  win_T       *old_curwin = curwin;
+
+  /* don't use a new tab page, each tab page has its own diffs */
+  cmdmod.tab = 0;
+
+  if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL) {
+    /* Pretend it was a ":split fname" command */
+    eap->cmdidx = CMD_split;
+    curwin->w_p_diff = TRUE;
+    do_exedit(eap, old_curwin);
+
+    if (curwin != old_curwin) {                 /* split must have worked */
+      /* Set 'diff', 'scrollbind' on and 'wrap' off. */
+      diff_win_options(curwin, TRUE);
+      diff_win_options(old_curwin, TRUE);
+    }
+  }
+}
+
+/*
+ * Set options to show diffs for the current window.
+ */
+void ex_diffthis(eap)
+exarg_T     *eap UNUSED;
+{
+  /* Set 'diff', 'scrollbind' on and 'wrap' off. */
+  diff_win_options(curwin, TRUE);
+}
+
+/*
+ * Set options in window "wp" for diff mode.
+ */
+void diff_win_options(wp, addbuf)
+win_T       *wp;
+int addbuf;                     /* Add buffer to diff. */
+{
+  win_T *old_curwin = curwin;
+
+  /* close the manually opened folds */
+  curwin = wp;
+  newFoldLevel();
+  curwin = old_curwin;
+
+  wp->w_p_diff = TRUE;
+
+  /* Use 'scrollbind' and 'cursorbind' when available */
+  if (!wp->w_p_diff_saved)
+    wp->w_p_scb_save = wp->w_p_scb;
+  wp->w_p_scb = TRUE;
+  if (!wp->w_p_diff_saved)
+    wp->w_p_crb_save = wp->w_p_crb;
+  wp->w_p_crb = TRUE;
+  if (!wp->w_p_diff_saved)
+    wp->w_p_wrap_save = wp->w_p_wrap;
+  wp->w_p_wrap = FALSE;
+  curwin = wp;
+  curbuf = curwin->w_buffer;
+  if (!wp->w_p_diff_saved)
+    wp->w_p_fdm_save = vim_strsave(wp->w_p_fdm);
+  set_string_option_direct((char_u *)"fdm", -1, (char_u *)"diff",
+      OPT_LOCAL|OPT_FREE, 0);
+  curwin = old_curwin;
+  curbuf = curwin->w_buffer;
+  if (!wp->w_p_diff_saved) {
+    wp->w_p_fdc_save = wp->w_p_fdc;
+    wp->w_p_fen_save = wp->w_p_fen;
+    wp->w_p_fdl_save = wp->w_p_fdl;
+  }
+  wp->w_p_fdc = diff_foldcolumn;
+  wp->w_p_fen = TRUE;
+  wp->w_p_fdl = 0;
+  foldUpdateAll(wp);
+  /* make sure topline is not halfway a fold */
+  changed_window_setting_win(wp);
+  if (vim_strchr(p_sbo, 'h') == NULL)
+    do_cmdline_cmd((char_u *)"set sbo+=hor");
+  /* Saved the current values, to be restored in ex_diffoff(). */
+  wp->w_p_diff_saved = TRUE;
+
+  if (addbuf)
+    diff_buf_add(wp->w_buffer);
+  redraw_win_later(wp, NOT_VALID);
+}
+
+/*
+ * Set options not to show diffs.  For the current window or all windows.
+ * Only in the current tab page.
+ */
+void ex_diffoff(eap)
+exarg_T     *eap;
+{
+  win_T       *wp;
+  win_T       *old_curwin = curwin;
+  int diffwin = FALSE;
+
+  for (wp = firstwin; wp != NULL; wp = wp->w_next) {
+    if (eap->forceit ? wp->w_p_diff : wp == curwin) {
+      /* Set 'diff', 'scrollbind' off and 'wrap' on. If option values
+       * were saved in diff_win_options() restore them. */
+      wp->w_p_diff = FALSE;
+
+      if (wp->w_p_scb)
+        wp->w_p_scb = wp->w_p_diff_saved ? wp->w_p_scb_save : FALSE;
+      if (wp->w_p_crb)
+        wp->w_p_crb = wp->w_p_diff_saved ? wp->w_p_crb_save : FALSE;
+      if (!wp->w_p_wrap)
+        wp->w_p_wrap = wp->w_p_diff_saved ? wp->w_p_wrap_save : TRUE;
+      curwin = wp;
+      curbuf = curwin->w_buffer;
+      if (wp->w_p_diff_saved) {
+        free_string_option(wp->w_p_fdm);
+        wp->w_p_fdm = wp->w_p_fdm_save;
+        wp->w_p_fdm_save = empty_option;
+      } else
+        set_string_option_direct((char_u *)"fdm", -1,
+            (char_u *)"manual", OPT_LOCAL|OPT_FREE, 0);
+      curwin = old_curwin;
+      curbuf = curwin->w_buffer;
+      if (wp->w_p_fdc == diff_foldcolumn)
+        wp->w_p_fdc = wp->w_p_diff_saved ? wp->w_p_fdc_save : 0;
+      if (wp->w_p_fdl == 0 && wp->w_p_diff_saved)
+        wp->w_p_fdl = wp->w_p_fdl_save;
+
+      if (wp->w_p_fen) {
+        /* Only restore 'foldenable' when 'foldmethod' is not
+         * "manual", otherwise we continue to show the diff folds. */
+        if (foldmethodIsManual(wp) || !wp->w_p_diff_saved)
+          wp->w_p_fen = FALSE;
+        else
+          wp->w_p_fen = wp->w_p_fen_save;
+      }
+
+      foldUpdateAll(wp);
+      /* make sure topline is not halfway a fold */
+      changed_window_setting_win(wp);
+      /* Note: 'sbo' is not restored, it's a global option. */
+      diff_buf_adjust(wp);
+
+      wp->w_p_diff_saved = FALSE;
+    }
+    diffwin |= wp->w_p_diff;
+  }
+
+  /* Remove "hor" from from 'scrollopt' if there are no diff windows left. */
+  if (!diffwin && vim_strchr(p_sbo, 'h') != NULL)
+    do_cmdline_cmd((char_u *)"set sbo-=hor");
+}
+
+/*
+ * Read the diff output and add each entry to the diff list.
+ */
+static void diff_read(idx_orig, idx_new, fname)
+int idx_orig;                   /* idx of original file */
+int idx_new;                    /* idx of new file */
+char_u      *fname;             /* name of diff output file */
+{
+  FILE        *fd;
+  diff_T      *dprev = NULL;
+  diff_T      *dp = curtab->tp_first_diff;
+  diff_T      *dn, *dpl;
+  long f1, l1, f2, l2;
+  char_u linebuf[LBUFLEN];          /* only need to hold the diff line */
+  int difftype;
+  char_u      *p;
+  long off;
+  int i;
+  linenr_T lnum_orig, lnum_new;
+  long count_orig, count_new;
+  int notset = TRUE;                /* block "*dp" not set yet */
+
+  fd = mch_fopen((char *)fname, "r");
+  if (fd == NULL) {
+    EMSG(_("E98: Cannot read diff output"));
+    return;
+  }
+
+  for (;; ) {
+    if (tag_fgets(linebuf, LBUFLEN, fd))
+      break;                    /* end of file */
+    if (!isdigit(*linebuf))
+      continue;                 /* not the start of a diff block */
+
+    /* This line must be one of three formats:
+     * {first}[,{last}]c{first}[,{last}]
+     * {first}a{first}[,{last}]
+     * {first}[,{last}]d{first}
+     */
+    p = linebuf;
+    f1 = getdigits(&p);
+    if (*p == ',') {
+      ++p;
+      l1 = getdigits(&p);
+    } else
+      l1 = f1;
+    if (*p != 'a' && *p != 'c' && *p != 'd')
+      continue;                 /* invalid diff format */
+    difftype = *p++;
+    f2 = getdigits(&p);
+    if (*p == ',') {
+      ++p;
+      l2 = getdigits(&p);
+    } else
+      l2 = f2;
+    if (l1 < f1 || l2 < f2)
+      continue;                 /* invalid line range */
+
+    if (difftype == 'a') {
+      lnum_orig = f1 + 1;
+      count_orig = 0;
+    } else   {
+      lnum_orig = f1;
+      count_orig = l1 - f1 + 1;
+    }
+    if (difftype == 'd') {
+      lnum_new = f2 + 1;
+      count_new = 0;
+    } else   {
+      lnum_new = f2;
+      count_new = l2 - f2 + 1;
+    }
+
+    /* Go over blocks before the change, for which orig and new are equal.
+     * Copy blocks from orig to new. */
+    while (dp != NULL
+           && lnum_orig > dp->df_lnum[idx_orig] + dp->df_count[idx_orig]) {
+      if (notset)
+        diff_copy_entry(dprev, dp, idx_orig, idx_new);
+      dprev = dp;
+      dp = dp->df_next;
+      notset = TRUE;
+    }
+
+    if (dp != NULL
+        && lnum_orig <= dp->df_lnum[idx_orig] + dp->df_count[idx_orig]
+        && lnum_orig + count_orig >= dp->df_lnum[idx_orig]) {
+      /* New block overlaps with existing block(s).
+       * First find last block that overlaps. */
+      for (dpl = dp; dpl->df_next != NULL; dpl = dpl->df_next)
+        if (lnum_orig + count_orig < dpl->df_next->df_lnum[idx_orig])
+          break;
+
+      /* If the newly found block starts before the old one, set the
+       * start back a number of lines. */
+      off = dp->df_lnum[idx_orig] - lnum_orig;
+      if (off > 0) {
+        for (i = idx_orig; i < idx_new; ++i)
+          if (curtab->tp_diffbuf[i] != NULL)
+            dp->df_lnum[i] -= off;
+        dp->df_lnum[idx_new] = lnum_new;
+        dp->df_count[idx_new] = count_new;
+      } else if (notset)   {
+        /* new block inside existing one, adjust new block */
+        dp->df_lnum[idx_new] = lnum_new + off;
+        dp->df_count[idx_new] = count_new - off;
+      } else
+        /* second overlap of new block with existing block */
+        dp->df_count[idx_new] += count_new - count_orig
+                                 + dpl->df_lnum[idx_orig] +
+                                 dpl->df_count[idx_orig]
+                                 - (dp->df_lnum[idx_orig] +
+                                    dp->df_count[idx_orig]);
+
+      /* Adjust the size of the block to include all the lines to the
+       * end of the existing block or the new diff, whatever ends last. */
+      off = (lnum_orig + count_orig)
+            - (dpl->df_lnum[idx_orig] + dpl->df_count[idx_orig]);
+      if (off < 0) {
+        /* new change ends in existing block, adjust the end if not
+         * done already */
+        if (notset)
+          dp->df_count[idx_new] += -off;
+        off = 0;
+      }
+      for (i = idx_orig; i < idx_new; ++i)
+        if (curtab->tp_diffbuf[i] != NULL)
+          dp->df_count[i] = dpl->df_lnum[i] + dpl->df_count[i]
+                            - dp->df_lnum[i] + off;
+
+      /* Delete the diff blocks that have been merged into one. */
+      dn = dp->df_next;
+      dp->df_next = dpl->df_next;
+      while (dn != dp->df_next) {
+        dpl = dn->df_next;
+        vim_free(dn);
+        dn = dpl;
+      }
+    } else   {
+      /* Allocate a new diffblock. */
+      dp = diff_alloc_new(curtab, dprev, dp);
+      if (dp == NULL)
+        goto done;
+
+      dp->df_lnum[idx_orig] = lnum_orig;
+      dp->df_count[idx_orig] = count_orig;
+      dp->df_lnum[idx_new] = lnum_new;
+      dp->df_count[idx_new] = count_new;
+
+      /* Set values for other buffers, these must be equal to the
+       * original buffer, otherwise there would have been a change
+       * already. */
+      for (i = idx_orig + 1; i < idx_new; ++i)
+        if (curtab->tp_diffbuf[i] != NULL)
+          diff_copy_entry(dprev, dp, idx_orig, i);
+    }
+    notset = FALSE;             /* "*dp" has been set */
+  }
+
+  /* for remaining diff blocks orig and new are equal */
+  while (dp != NULL) {
+    if (notset)
+      diff_copy_entry(dprev, dp, idx_orig, idx_new);
+    dprev = dp;
+    dp = dp->df_next;
+    notset = TRUE;
+  }
+
+done:
+  fclose(fd);
+}
+
+/*
+ * Copy an entry at "dp" from "idx_orig" to "idx_new".
+ */
+static void diff_copy_entry(dprev, dp, idx_orig, idx_new)
+diff_T      *dprev;
+diff_T      *dp;
+int idx_orig;
+int idx_new;
+{
+  long off;
+
+  if (dprev == NULL)
+    off = 0;
+  else
+    off = (dprev->df_lnum[idx_orig] + dprev->df_count[idx_orig])
+          - (dprev->df_lnum[idx_new] + dprev->df_count[idx_new]);
+  dp->df_lnum[idx_new] = dp->df_lnum[idx_orig] - off;
+  dp->df_count[idx_new] = dp->df_count[idx_orig];
+}
+
+/*
+ * Clear the list of diffblocks for tab page "tp".
+ */
+void diff_clear(tp)
+tabpage_T   *tp;
+{
+  diff_T      *p, *next_p;
+
+  for (p = tp->tp_first_diff; p != NULL; p = next_p) {
+    next_p = p->df_next;
+    vim_free(p);
+  }
+  tp->tp_first_diff = NULL;
+}
+
+/*
+ * Check diff status for line "lnum" in buffer "buf":
+ * Returns 0 for nothing special
+ * Returns -1 for a line that should be highlighted as changed.
+ * Returns -2 for a line that should be highlighted as added/deleted.
+ * Returns > 0 for inserting that many filler lines above it (never happens
+ * when 'diffopt' doesn't contain "filler").
+ * This should only be used for windows where 'diff' is set.
+ */
+int diff_check(wp, lnum)
+win_T       *wp;
+linenr_T lnum;
+{
+  int idx;                      /* index in tp_diffbuf[] for this buffer */
+  diff_T      *dp;
+  int maxcount;
+  int i;
+  buf_T       *buf = wp->w_buffer;
+  int cmp;
+
+  if (curtab->tp_diff_invalid)
+    ex_diffupdate(NULL);                /* update after a big change */
+
+  if (curtab->tp_first_diff == NULL || !wp->w_p_diff)   /* no diffs at all */
+    return 0;
+
+  /* safety check: "lnum" must be a buffer line */
+  if (lnum < 1 || lnum > buf->b_ml.ml_line_count + 1)
+    return 0;
+
+  idx = diff_buf_idx(buf);
+  if (idx == DB_COUNT)
+    return 0;                   /* no diffs for buffer "buf" */
+
+  /* A closed fold never has filler lines. */
+  if (hasFoldingWin(wp, lnum, NULL, NULL, TRUE, NULL))
+    return 0;
+
+  /* search for a change that includes "lnum" in the list of diffblocks. */
+  for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
+    if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
+      break;
+  if (dp == NULL || lnum < dp->df_lnum[idx])
+    return 0;
+
+  if (lnum < dp->df_lnum[idx] + dp->df_count[idx]) {
+    int zero = FALSE;
+
+    /* Changed or inserted line.  If the other buffers have a count of
+     * zero, the lines were inserted.  If the other buffers have the same
+     * count, check if the lines are identical. */
+    cmp = FALSE;
+    for (i = 0; i < DB_COUNT; ++i)
+      if (i != idx && curtab->tp_diffbuf[i] != NULL) {
+        if (dp->df_count[i] == 0)
+          zero = TRUE;
+        else {
+          if (dp->df_count[i] != dp->df_count[idx])
+            return -1;                      /* nr of lines changed. */
+          cmp = TRUE;
+        }
+      }
+    if (cmp) {
+      /* Compare all lines.  If they are equal the lines were inserted
+       * in some buffers, deleted in others, but not changed. */
+      for (i = 0; i < DB_COUNT; ++i)
+        if (i != idx && curtab->tp_diffbuf[i] != NULL && dp->df_count[i] != 0)
+          if (!diff_equal_entry(dp, idx, i))
+            return -1;
+    }
+    /* If there is no buffer with zero lines then there is no difference
+     * any longer.  Happens when making a change (or undo) that removes
+     * the difference.  Can't remove the entry here, we might be halfway
+     * updating the window.  Just report the text as unchanged.  Other
+     * windows might still show the change though. */
+    if (zero == FALSE)
+      return 0;
+    return -2;
+  }
+
+  /* If 'diffopt' doesn't contain "filler", return 0. */
+  if (!(diff_flags & DIFF_FILLER))
+    return 0;
+
+  /* Insert filler lines above the line just below the change.  Will return
+   * 0 when this buf had the max count. */
+  maxcount = 0;
+  for (i = 0; i < DB_COUNT; ++i)
+    if (curtab->tp_diffbuf[i] != NULL && dp->df_count[i] > maxcount)
+      maxcount = dp->df_count[i];
+  return maxcount - dp->df_count[idx];
+}
+
+/*
+ * Compare two entries in diff "*dp" and return TRUE if they are equal.
+ */
+static int diff_equal_entry(dp, idx1, idx2)
+diff_T      *dp;
+int idx1;
+int idx2;
+{
+  int i;
+  char_u      *line;
+  int cmp;
+
+  if (dp->df_count[idx1] != dp->df_count[idx2])
+    return FALSE;
+  if (diff_check_sanity(curtab, dp) == FAIL)
+    return FALSE;
+  for (i = 0; i < dp->df_count[idx1]; ++i) {
+    line = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx1],
+            dp->df_lnum[idx1] + i, FALSE));
+    if (line == NULL)
+      return FALSE;
+    cmp = diff_cmp(line, ml_get_buf(curtab->tp_diffbuf[idx2],
+            dp->df_lnum[idx2] + i, FALSE));
+    vim_free(line);
+    if (cmp != 0)
+      return FALSE;
+  }
+  return TRUE;
+}
+
+/*
+ * Compare strings "s1" and "s2" according to 'diffopt'.
+ * Return non-zero when they are different.
+ */
+static int diff_cmp(s1, s2)
+char_u      *s1;
+char_u      *s2;
+{
+  char_u      *p1, *p2;
+  int l;
+
+  if ((diff_flags & (DIFF_ICASE | DIFF_IWHITE)) == 0)
+    return STRCMP(s1, s2);
+  if ((diff_flags & DIFF_ICASE) && !(diff_flags & DIFF_IWHITE))
+    return MB_STRICMP(s1, s2);
+
+  /* Ignore white space changes and possibly ignore case. */
+  p1 = s1;
+  p2 = s2;
+  while (*p1 != NUL && *p2 != NUL) {
+    if (vim_iswhite(*p1) && vim_iswhite(*p2)) {
+      p1 = skipwhite(p1);
+      p2 = skipwhite(p2);
+    } else   {
+      l  = (*mb_ptr2len)(p1);
+      if (l != (*mb_ptr2len)(p2))
+        break;
+      if (l > 1) {
+        if (STRNCMP(p1, p2, l) != 0
+            && (!enc_utf8
+                || !(diff_flags & DIFF_ICASE)
+                || utf_fold(utf_ptr2char(p1))
+                != utf_fold(utf_ptr2char(p2))))
+          break;
+        p1 += l;
+        p2 += l;
+      } else   {
+        if (*p1 != *p2 && (!(diff_flags & DIFF_ICASE)
+                           || TOLOWER_LOC(*p1) != TOLOWER_LOC(*p2)))
+          break;
+        ++p1;
+        ++p2;
+      }
+    }
+  }
+
+  /* Ignore trailing white space. */
+  p1 = skipwhite(p1);
+  p2 = skipwhite(p2);
+  if (*p1 != NUL || *p2 != NUL)
+    return 1;
+  return 0;
+}
+
+/*
+ * Return the number of filler lines above "lnum".
+ */
+int diff_check_fill(wp, lnum)
+win_T       *wp;
+linenr_T lnum;
+{
+  int n;
+
+  /* be quick when there are no filler lines */
+  if (!(diff_flags & DIFF_FILLER))
+    return 0;
+  n = diff_check(wp, lnum);
+  if (n <= 0)
+    return 0;
+  return n;
+}
+
+/*
+ * Set the topline of "towin" to match the position in "fromwin", so that they
+ * show the same diff'ed lines.
+ */
+void diff_set_topline(fromwin, towin)
+win_T       *fromwin;
+win_T       *towin;
+{
+  buf_T       *frombuf = fromwin->w_buffer;
+  linenr_T lnum = fromwin->w_topline;
+  int fromidx;
+  int toidx;
+  diff_T      *dp;
+  int max_count;
+  int i;
+
+  fromidx = diff_buf_idx(frombuf);
+  if (fromidx == DB_COUNT)
+    return;             /* safety check */
+
+  if (curtab->tp_diff_invalid)
+    ex_diffupdate(NULL);                /* update after a big change */
+
+  towin->w_topfill = 0;
+
+  /* search for a change that includes "lnum" in the list of diffblocks. */
+  for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
+    if (lnum <= dp->df_lnum[fromidx] + dp->df_count[fromidx])
+      break;
+  if (dp == NULL) {
+    /* After last change, compute topline relative to end of file; no
+     * filler lines. */
+    towin->w_topline = towin->w_buffer->b_ml.ml_line_count
+                       - (frombuf->b_ml.ml_line_count - lnum);
+  } else   {
+    /* Find index for "towin". */
+    toidx = diff_buf_idx(towin->w_buffer);
+    if (toidx == DB_COUNT)
+      return;                   /* safety check */
+
+    towin->w_topline = lnum + (dp->df_lnum[toidx] - dp->df_lnum[fromidx]);
+    if (lnum >= dp->df_lnum[fromidx]) {
+      /* Inside a change: compute filler lines. With three or more
+       * buffers we need to know the largest count. */
+      max_count = 0;
+      for (i = 0; i < DB_COUNT; ++i)
+        if (curtab->tp_diffbuf[i] != NULL
+            && max_count < dp->df_count[i])
+          max_count = dp->df_count[i];
+
+      if (dp->df_count[toidx] == dp->df_count[fromidx]) {
+        /* same number of lines: use same filler count */
+        towin->w_topfill = fromwin->w_topfill;
+      } else if (dp->df_count[toidx] > dp->df_count[fromidx])   {
+        if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx]) {
+          /* more lines in towin and fromwin doesn't show diff
+           * lines, only filler lines */
+          if (max_count - fromwin->w_topfill >= dp->df_count[toidx]) {
+            /* towin also only shows filler lines */
+            towin->w_topline = dp->df_lnum[toidx]
+                               + dp->df_count[toidx];
+            towin->w_topfill = fromwin->w_topfill;
+          } else
+            /* towin still has some diff lines to show */
+            towin->w_topline = dp->df_lnum[toidx]
+                               + max_count - fromwin->w_topfill;
+        }
+      } else if (towin->w_topline >= dp->df_lnum[toidx]
+                 + dp->df_count[toidx]) {
+        /* less lines in towin and no diff lines to show: compute
+         * filler lines */
+        towin->w_topline = dp->df_lnum[toidx] + dp->df_count[toidx];
+        if (diff_flags & DIFF_FILLER) {
+          if (lnum == dp->df_lnum[fromidx] + dp->df_count[fromidx])
+            /* fromwin is also out of diff lines */
+            towin->w_topfill = fromwin->w_topfill;
+          else
+            /* fromwin has some diff lines */
+            towin->w_topfill = dp->df_lnum[fromidx]
+                               + max_count - lnum;
+        }
+      }
+    }
+  }
+
+  /* safety check (if diff info gets outdated strange things may happen) */
+  towin->w_botfill = FALSE;
+  if (towin->w_topline > towin->w_buffer->b_ml.ml_line_count) {
+    towin->w_topline = towin->w_buffer->b_ml.ml_line_count;
+    towin->w_botfill = TRUE;
+  }
+  if (towin->w_topline < 1) {
+    towin->w_topline = 1;
+    towin->w_topfill = 0;
+  }
+
+  /* When w_topline changes need to recompute w_botline and cursor position */
+  invalidate_botline_win(towin);
+  changed_line_abv_curs_win(towin);
+
+  check_topfill(towin, FALSE);
+  (void)hasFoldingWin(towin, towin->w_topline, &towin->w_topline,
+      NULL, TRUE, NULL);
+}
+
+/*
+ * This is called when 'diffopt' is changed.
+ */
+int diffopt_changed()         {
+  char_u      *p;
+  int diff_context_new = 6;
+  int diff_flags_new = 0;
+  int diff_foldcolumn_new = 2;
+  tabpage_T   *tp;
+
+  p = p_dip;
+  while (*p != NUL) {
+    if (STRNCMP(p, "filler", 6) == 0) {
+      p += 6;
+      diff_flags_new |= DIFF_FILLER;
+    } else if (STRNCMP(p, "context:", 8) == 0 && VIM_ISDIGIT(p[8]))   {
+      p += 8;
+      diff_context_new = getdigits(&p);
+    } else if (STRNCMP(p, "icase", 5) == 0)   {
+      p += 5;
+      diff_flags_new |= DIFF_ICASE;
+    } else if (STRNCMP(p, "iwhite", 6) == 0)   {
+      p += 6;
+      diff_flags_new |= DIFF_IWHITE;
+    } else if (STRNCMP(p, "horizontal", 10) == 0)   {
+      p += 10;
+      diff_flags_new |= DIFF_HORIZONTAL;
+    } else if (STRNCMP(p, "vertical", 8) == 0)   {
+      p += 8;
+      diff_flags_new |= DIFF_VERTICAL;
+    } else if (STRNCMP(p, "foldcolumn:", 11) == 0 && VIM_ISDIGIT(p[11]))   {
+      p += 11;
+      diff_foldcolumn_new = getdigits(&p);
+    }
+    if (*p != ',' && *p != NUL)
+      return FAIL;
+    if (*p == ',')
+      ++p;
+  }
+
+  /* Can't have both "horizontal" and "vertical". */
+  if ((diff_flags_new & DIFF_HORIZONTAL) && (diff_flags_new & DIFF_VERTICAL))
+    return FAIL;
+
+  /* If "icase" or "iwhite" was added or removed, need to update the diff. */
+  if (diff_flags != diff_flags_new)
+    for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
+      tp->tp_diff_invalid = TRUE;
+
+  diff_flags = diff_flags_new;
+  diff_context = diff_context_new;
+  diff_foldcolumn = diff_foldcolumn_new;
+
+  diff_redraw(TRUE);
+
+  /* recompute the scroll binding with the new option value, may
+   * remove or add filler lines */
+  check_scrollbind((linenr_T)0, 0L);
+
+  return OK;
+}
+
+/*
+ * Return TRUE if 'diffopt' contains "horizontal".
+ */
+int diffopt_horizontal()         {
+  return (diff_flags & DIFF_HORIZONTAL) != 0;
+}
+
+/*
+ * Find the difference within a changed line.
+ * Returns TRUE if the line was added, no other buffer has it.
+ */
+int diff_find_change(wp, lnum, startp, endp)
+win_T       *wp;
+linenr_T lnum;
+int         *startp;            /* first char of the change */
+int         *endp;              /* last char of the change */
+{
+  char_u      *line_org;
+  char_u      *line_new;
+  int i;
+  int si_org, si_new;
+  int ei_org, ei_new;
+  diff_T      *dp;
+  int idx;
+  int off;
+  int added = TRUE;
+
+  /* Make a copy of the line, the next ml_get() will invalidate it. */
+  line_org = vim_strsave(ml_get_buf(wp->w_buffer, lnum, FALSE));
+  if (line_org == NULL)
+    return FALSE;
+
+  idx = diff_buf_idx(wp->w_buffer);
+  if (idx == DB_COUNT) {        /* cannot happen */
+    vim_free(line_org);
+    return FALSE;
+  }
+
+  /* search for a change that includes "lnum" in the list of diffblocks. */
+  for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
+    if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
+      break;
+  if (dp == NULL || diff_check_sanity(curtab, dp) == FAIL) {
+    vim_free(line_org);
+    return FALSE;
+  }
+
+  off = lnum - dp->df_lnum[idx];
+
+  for (i = 0; i < DB_COUNT; ++i)
+    if (curtab->tp_diffbuf[i] != NULL && i != idx) {
+      /* Skip lines that are not in the other change (filler lines). */
+      if (off >= dp->df_count[i])
+        continue;
+      added = FALSE;
+      line_new = ml_get_buf(curtab->tp_diffbuf[i],
+          dp->df_lnum[i] + off, FALSE);
+
+      /* Search for start of difference */
+      si_org = si_new = 0;
+      while (line_org[si_org] != NUL) {
+        if ((diff_flags & DIFF_IWHITE)
+            && vim_iswhite(line_org[si_org])
+            && vim_iswhite(line_new[si_new])) {
+          si_org = (int)(skipwhite(line_org + si_org) - line_org);
+          si_new = (int)(skipwhite(line_new + si_new) - line_new);
+        } else   {
+          if (line_org[si_org] != line_new[si_new])
+            break;
+          ++si_org;
+          ++si_new;
+        }
+      }
+      if (has_mbyte) {
+        /* Move back to first byte of character in both lines (may
+         * have "nn^" in line_org and "n^ in line_new). */
+        si_org -= (*mb_head_off)(line_org, line_org + si_org);
+        si_new -= (*mb_head_off)(line_new, line_new + si_new);
+      }
+      if (*startp > si_org)
+        *startp = si_org;
+
+      /* Search for end of difference, if any. */
+      if (line_org[si_org] != NUL || line_new[si_new] != NUL) {
+        ei_org = (int)STRLEN(line_org);
+        ei_new = (int)STRLEN(line_new);
+        while (ei_org >= *startp && ei_new >= si_new
+               && ei_org >= 0 && ei_new >= 0) {
+          if ((diff_flags & DIFF_IWHITE)
+              && vim_iswhite(line_org[ei_org])
+              && vim_iswhite(line_new[ei_new])) {
+            while (ei_org >= *startp
+                   && vim_iswhite(line_org[ei_org]))
+              --ei_org;
+            while (ei_new >= si_new
+                   && vim_iswhite(line_new[ei_new]))
+              --ei_new;
+          } else   {
+            if (line_org[ei_org] != line_new[ei_new])
+              break;
+            --ei_org;
+            --ei_new;
+          }
+        }
+        if (*endp < ei_org)
+          *endp = ei_org;
+      }
+    }
+
+  vim_free(line_org);
+  return added;
+}
+
+/*
+ * Return TRUE if line "lnum" is not close to a diff block, this line should
+ * be in a fold.
+ * Return FALSE if there are no diff blocks at all in this window.
+ */
+int diff_infold(wp, lnum)
+win_T       *wp;
+linenr_T lnum;
+{
+  int i;
+  int idx = -1;
+  int other = FALSE;
+  diff_T      *dp;
+
+  /* Return if 'diff' isn't set. */
+  if (!wp->w_p_diff)
+    return FALSE;
+
+  for (i = 0; i < DB_COUNT; ++i) {
+    if (curtab->tp_diffbuf[i] == wp->w_buffer)
+      idx = i;
+    else if (curtab->tp_diffbuf[i] != NULL)
+      other = TRUE;
+  }
+
+  /* return here if there are no diffs in the window */
+  if (idx == -1 || !other)
+    return FALSE;
+
+  if (curtab->tp_diff_invalid)
+    ex_diffupdate(NULL);                /* update after a big change */
+
+  /* Return if there are no diff blocks.  All lines will be folded. */
+  if (curtab->tp_first_diff == NULL)
+    return TRUE;
+
+  for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next) {
+    /* If this change is below the line there can't be any further match. */
+    if (dp->df_lnum[idx] - diff_context > lnum)
+      break;
+    /* If this change ends before the line we have a match. */
+    if (dp->df_lnum[idx] + dp->df_count[idx] + diff_context > lnum)
+      return FALSE;
+  }
+  return TRUE;
+}
+
+/*
+ * "dp" and "do" commands.
+ */
+void nv_diffgetput(put)
+int put;
+{
+  exarg_T ea;
+
+  ea.arg = (char_u *)"";
+  if (put)
+    ea.cmdidx = CMD_diffput;
+  else
+    ea.cmdidx = CMD_diffget;
+  ea.addr_count = 0;
+  ea.line1 = curwin->w_cursor.lnum;
+  ea.line2 = curwin->w_cursor.lnum;
+  ex_diffgetput(&ea);
+}
+
+/*
+ * ":diffget"
+ * ":diffput"
+ */
+void ex_diffgetput(eap)
+exarg_T     *eap;
+{
+  linenr_T lnum;
+  int count;
+  linenr_T off = 0;
+  diff_T      *dp;
+  diff_T      *dprev;
+  diff_T      *dfree;
+  int idx_cur;
+  int idx_other;
+  int idx_from;
+  int idx_to;
+  int i;
+  int added;
+  char_u      *p;
+  aco_save_T aco;
+  buf_T       *buf;
+  int start_skip, end_skip;
+  int new_count;
+  int buf_empty;
+  int found_not_ma = FALSE;
+
+  /* Find the current buffer in the list of diff buffers. */
+  idx_cur = diff_buf_idx(curbuf);
+  if (idx_cur == DB_COUNT) {
+    EMSG(_("E99: Current buffer is not in diff mode"));
+    return;
+  }
+
+  if (*eap->arg == NUL) {
+    /* No argument: Find the other buffer in the list of diff buffers. */
+    for (idx_other = 0; idx_other < DB_COUNT; ++idx_other)
+      if (curtab->tp_diffbuf[idx_other] != curbuf
+          && curtab->tp_diffbuf[idx_other] != NULL) {
+        if (eap->cmdidx != CMD_diffput
+            || curtab->tp_diffbuf[idx_other]->b_p_ma)
+          break;
+        found_not_ma = TRUE;
+      }
+    if (idx_other == DB_COUNT) {
+      if (found_not_ma)
+        EMSG(_("E793: No other buffer in diff mode is modifiable"));
+      else
+        EMSG(_("E100: No other buffer in diff mode"));
+      return;
+    }
+
+    /* Check that there isn't a third buffer in the list */
+    for (i = idx_other + 1; i < DB_COUNT; ++i)
+      if (curtab->tp_diffbuf[i] != curbuf
+          && curtab->tp_diffbuf[i] != NULL
+          && (eap->cmdidx != CMD_diffput || curtab->tp_diffbuf[i]->b_p_ma)) {
+        EMSG(_(
+                "E101: More than two buffers in diff mode, don't know which one to use"));
+        return;
+      }
+  } else   {
+    /* Buffer number or pattern given.  Ignore trailing white space. */
+    p = eap->arg + STRLEN(eap->arg);
+    while (p > eap->arg && vim_iswhite(p[-1]))
+      --p;
+    for (i = 0; vim_isdigit(eap->arg[i]) && eap->arg + i < p; ++i)
+      ;
+    if (eap->arg + i == p)          /* digits only */
+      i = atol((char *)eap->arg);
+    else {
+      i = buflist_findpat(eap->arg, p, FALSE, TRUE, FALSE);
+      if (i < 0)
+        return;                 /* error message already given */
+    }
+    buf = buflist_findnr(i);
+    if (buf == NULL) {
+      EMSG2(_("E102: Can't find buffer \"%s\""), eap->arg);
+      return;
+    }
+    if (buf == curbuf)
+      return;                   /* nothing to do */
+    idx_other = diff_buf_idx(buf);
+    if (idx_other == DB_COUNT) {
+      EMSG2(_("E103: Buffer \"%s\" is not in diff mode"), eap->arg);
+      return;
+    }
+  }
+
+  diff_busy = TRUE;
+
+  /* When no range given include the line above or below the cursor. */
+  if (eap->addr_count == 0) {
+    /* Make it possible that ":diffget" on the last line gets line below
+     * the cursor line when there is no difference above the cursor. */
+    if (eap->cmdidx == CMD_diffget
+        && eap->line1 == curbuf->b_ml.ml_line_count
+        && diff_check(curwin, eap->line1) == 0
+        && (eap->line1 == 1 || diff_check(curwin, eap->line1 - 1) == 0))
+      ++eap->line2;
+    else if (eap->line1 > 0)
+      --eap->line1;
+  }
+
+  if (eap->cmdidx == CMD_diffget) {
+    idx_from = idx_other;
+    idx_to = idx_cur;
+  } else   {
+    idx_from = idx_cur;
+    idx_to = idx_other;
+    /* Need to make the other buffer the current buffer to be able to make
+     * changes in it. */
+    /* set curwin/curbuf to buf and save a few things */
+    aucmd_prepbuf(&aco, curtab->tp_diffbuf[idx_other]);
+  }
+
+  /* May give the warning for a changed buffer here, which can trigger the
+   * FileChangedRO autocommand, which may do nasty things and mess
+   * everything up. */
+  if (!curbuf->b_changed) {
+    change_warning(0);
+    if (diff_buf_idx(curbuf) != idx_to) {
+      EMSG(_("E787: Buffer changed unexpectedly"));
+      return;
+    }
+  }
+
+  dprev = NULL;
+  for (dp = curtab->tp_first_diff; dp != NULL; ) {
+    if (dp->df_lnum[idx_cur] > eap->line2 + off)
+      break;            /* past the range that was specified */
+
+    dfree = NULL;
+    lnum = dp->df_lnum[idx_to];
+    count = dp->df_count[idx_to];
+    if (dp->df_lnum[idx_cur] + dp->df_count[idx_cur] > eap->line1 + off
+        && u_save(lnum - 1, lnum + count) != FAIL) {
+      /* Inside the specified range and saving for undo worked. */
+      start_skip = 0;
+      end_skip = 0;
+      if (eap->addr_count > 0) {
+        /* A range was specified: check if lines need to be skipped. */
+        start_skip = eap->line1 + off - dp->df_lnum[idx_cur];
+        if (start_skip > 0) {
+          /* range starts below start of current diff block */
+          if (start_skip > count) {
+            lnum += count;
+            count = 0;
+          } else   {
+            count -= start_skip;
+            lnum += start_skip;
+          }
+        } else
+          start_skip = 0;
+
+        end_skip = dp->df_lnum[idx_cur] + dp->df_count[idx_cur] - 1
+                   - (eap->line2 + off);
+        if (end_skip > 0) {
+          /* range ends above end of current/from diff block */
+          if (idx_cur == idx_from) {            /* :diffput */
+            i = dp->df_count[idx_cur] - start_skip - end_skip;
+            if (count > i)
+              count = i;
+          } else   {                            /* :diffget */
+            count -= end_skip;
+            end_skip = dp->df_count[idx_from] - start_skip - count;
+            if (end_skip < 0)
+              end_skip = 0;
+          }
+        } else
+          end_skip = 0;
+      }
+
+      buf_empty = FALSE;
+      added = 0;
+      for (i = 0; i < count; ++i) {
+        /* remember deleting the last line of the buffer */
+        buf_empty = curbuf->b_ml.ml_line_count == 1;
+        ml_delete(lnum, FALSE);
+        --added;
+      }
+      for (i = 0; i < dp->df_count[idx_from] - start_skip - end_skip; ++i) {
+        linenr_T nr;
+
+        nr = dp->df_lnum[idx_from] + start_skip + i;
+        if (nr > curtab->tp_diffbuf[idx_from]->b_ml.ml_line_count)
+          break;
+        p = vim_strsave(ml_get_buf(curtab->tp_diffbuf[idx_from],
+                nr, FALSE));
+        if (p != NULL) {
+          ml_append(lnum + i - 1, p, 0, FALSE);
+          vim_free(p);
+          ++added;
+          if (buf_empty && curbuf->b_ml.ml_line_count == 2) {
+            /* Added the first line into an empty buffer, need to
+             * delete the dummy empty line. */
+            buf_empty = FALSE;
+            ml_delete((linenr_T)2, FALSE);
+          }
+        }
+      }
+      new_count = dp->df_count[idx_to] + added;
+      dp->df_count[idx_to] = new_count;
+
+      if (start_skip == 0 && end_skip == 0) {
+        /* Check if there are any other buffers and if the diff is
+         * equal in them. */
+        for (i = 0; i < DB_COUNT; ++i)
+          if (curtab->tp_diffbuf[i] != NULL && i != idx_from
+              && i != idx_to
+              && !diff_equal_entry(dp, idx_from, i))
+            break;
+        if (i == DB_COUNT) {
+          /* delete the diff entry, the buffers are now equal here */
+          dfree = dp;
+          dp = dp->df_next;
+          if (dprev == NULL)
+            curtab->tp_first_diff = dp;
+          else
+            dprev->df_next = dp;
+        }
+      }
+
+      /* Adjust marks.  This will change the following entries! */
+      if (added != 0) {
+        mark_adjust(lnum, lnum + count - 1, (long)MAXLNUM, (long)added);
+        if (curwin->w_cursor.lnum >= lnum) {
+          /* Adjust the cursor position if it's in/after the changed
+           * lines. */
+          if (curwin->w_cursor.lnum >= lnum + count)
+            curwin->w_cursor.lnum += added;
+          else if (added < 0)
+            curwin->w_cursor.lnum = lnum;
+        }
+      }
+      changed_lines(lnum, 0, lnum + count, (long)added);
+
+      if (dfree != NULL) {
+        /* Diff is deleted, update folds in other windows. */
+        diff_fold_update(dfree, idx_to);
+        vim_free(dfree);
+      } else
+        /* mark_adjust() may have changed the count in a wrong way */
+        dp->df_count[idx_to] = new_count;
+
+      /* When changing the current buffer, keep track of line numbers */
+      if (idx_cur == idx_to)
+        off += added;
+    }
+
+    /* If before the range or not deleted, go to next diff. */
+    if (dfree == NULL) {
+      dprev = dp;
+      dp = dp->df_next;
+    }
+  }
+
+  /* restore curwin/curbuf and a few other things */
+  if (eap->cmdidx != CMD_diffget) {
+    /* Syncing undo only works for the current buffer, but we change
+     * another buffer.  Sync undo if the command was typed.  This isn't
+     * 100% right when ":diffput" is used in a function or mapping. */
+    if (KeyTyped)
+      u_sync(FALSE);
+    aucmd_restbuf(&aco);
+  }
+
+  diff_busy = FALSE;
+
+  /* Check that the cursor is on a valid character and update it's position.
+   * When there were filler lines the topline has become invalid. */
+  check_cursor();
+  changed_line_abv_curs();
+
+  /* Also need to redraw the other buffers. */
+  diff_redraw(FALSE);
+}
+
+/*
+ * Update folds for all diff buffers for entry "dp".
+ * Skip buffer with index "skip_idx".
+ * When there are no diffs, all folds are removed.
+ */
+static void diff_fold_update(dp, skip_idx)
+diff_T      *dp;
+int skip_idx;
+{
+  int i;
+  win_T       *wp;
+
+  for (wp = firstwin; wp != NULL; wp = wp->w_next)
+    for (i = 0; i < DB_COUNT; ++i)
+      if (curtab->tp_diffbuf[i] == wp->w_buffer && i != skip_idx)
+        foldUpdate(wp, dp->df_lnum[i],
+            dp->df_lnum[i] + dp->df_count[i]);
+}
+
+/*
+ * Return TRUE if buffer "buf" is in diff-mode.
+ */
+int diff_mode_buf(buf)
+buf_T       *buf;
+{
+  tabpage_T   *tp;
+
+  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
+    if (diff_buf_idx_tp(buf, tp) != DB_COUNT)
+      return TRUE;
+  return FALSE;
+}
+
+/*
+ * Move "count" times in direction "dir" to the next diff block.
+ * Return FAIL if there isn't such a diff block.
+ */
+int diff_move_to(dir, count)
+int dir;
+long count;
+{
+  int idx;
+  linenr_T lnum = curwin->w_cursor.lnum;
+  diff_T      *dp;
+
+  idx = diff_buf_idx(curbuf);
+  if (idx == DB_COUNT || curtab->tp_first_diff == NULL)
+    return FAIL;
+
+  if (curtab->tp_diff_invalid)
+    ex_diffupdate(NULL);                /* update after a big change */
+
+  if (curtab->tp_first_diff == NULL)            /* no diffs today */
+    return FAIL;
+
+  while (--count >= 0) {
+    /* Check if already before first diff. */
+    if (dir == BACKWARD && lnum <= curtab->tp_first_diff->df_lnum[idx])
+      break;
+
+    for (dp = curtab->tp_first_diff;; dp = dp->df_next) {
+      if (dp == NULL)
+        break;
+      if ((dir == FORWARD && lnum < dp->df_lnum[idx])
+          || (dir == BACKWARD
+              && (dp->df_next == NULL
+                  || lnum <= dp->df_next->df_lnum[idx]))) {
+        lnum = dp->df_lnum[idx];
+        break;
+      }
+    }
+  }
+
+  /* don't end up past the end of the file */
+  if (lnum > curbuf->b_ml.ml_line_count)
+    lnum = curbuf->b_ml.ml_line_count;
+
+  /* When the cursor didn't move at all we fail. */
+  if (lnum == curwin->w_cursor.lnum)
+    return FAIL;
+
+  setpcmark();
+  curwin->w_cursor.lnum = lnum;
+  curwin->w_cursor.col = 0;
+
+  return OK;
+}
+
+linenr_T diff_get_corresponding_line(buf1, lnum1, buf2, lnum3)
+buf_T       *buf1;
+linenr_T lnum1;
+buf_T       *buf2;
+linenr_T lnum3;
+{
+  int idx1;
+  int idx2;
+  diff_T      *dp;
+  int baseline = 0;
+  linenr_T lnum2;
+
+  idx1 = diff_buf_idx(buf1);
+  idx2 = diff_buf_idx(buf2);
+  if (idx1 == DB_COUNT || idx2 == DB_COUNT || curtab->tp_first_diff == NULL)
+    return lnum1;
+
+  if (curtab->tp_diff_invalid)
+    ex_diffupdate(NULL);                /* update after a big change */
+
+  if (curtab->tp_first_diff == NULL)            /* no diffs today */
+    return lnum1;
+
+  for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next) {
+    if (dp->df_lnum[idx1] > lnum1) {
+      lnum2 = lnum1 - baseline;
+      /* don't end up past the end of the file */
+      if (lnum2 > buf2->b_ml.ml_line_count)
+        lnum2 = buf2->b_ml.ml_line_count;
+
+      return lnum2;
+    } else if ((dp->df_lnum[idx1] + dp->df_count[idx1]) > lnum1)   {
+      /* Inside the diffblock */
+      baseline = lnum1 - dp->df_lnum[idx1];
+      if (baseline > dp->df_count[idx2])
+        baseline = dp->df_count[idx2];
+
+      return dp->df_lnum[idx2] + baseline;
+    } else if (   (dp->df_lnum[idx1] == lnum1)
+                  && (dp->df_count[idx1] == 0)
+                  && (dp->df_lnum[idx2] <= lnum3)
+                  && ((dp->df_lnum[idx2] + dp->df_count[idx2]) > lnum3))
+      /*
+       * Special case: if the cursor is just after a zero-count
+       * block (i.e. all filler) and the target cursor is already
+       * inside the corresponding block, leave the target cursor
+       * unmoved. This makes repeated CTRL-W W operations work
+       * as expected.
+       */
+      return lnum3;
+    baseline = (dp->df_lnum[idx1] + dp->df_count[idx1])
+               - (dp->df_lnum[idx2] + dp->df_count[idx2]);
+  }
+
+  /* If we get here then the cursor is after the last diff */
+  lnum2 = lnum1 - baseline;
+  /* don't end up past the end of the file */
+  if (lnum2 > buf2->b_ml.ml_line_count)
+    lnum2 = buf2->b_ml.ml_line_count;
+
+  return lnum2;
+}
+
+/*
+ * For line "lnum" in the current window find the equivalent lnum in window
+ * "wp", compensating for inserted/deleted lines.
+ */
+linenr_T diff_lnum_win(lnum, wp)
+linenr_T lnum;
+win_T       *wp;
+{
+  diff_T      *dp;
+  int idx;
+  int i;
+  linenr_T n;
+
+  idx = diff_buf_idx(curbuf);
+  if (idx == DB_COUNT)                  /* safety check */
+    return (linenr_T)0;
+
+  if (curtab->tp_diff_invalid)
+    ex_diffupdate(NULL);                /* update after a big change */
+
+  /* search for a change that includes "lnum" in the list of diffblocks. */
+  for (dp = curtab->tp_first_diff; dp != NULL; dp = dp->df_next)
+    if (lnum <= dp->df_lnum[idx] + dp->df_count[idx])
+      break;
+
+  /* When after the last change, compute relative to the last line number. */
+  if (dp == NULL)
+    return wp->w_buffer->b_ml.ml_line_count
+           - (curbuf->b_ml.ml_line_count - lnum);
+
+  /* Find index for "wp". */
+  i = diff_buf_idx(wp->w_buffer);
+  if (i == DB_COUNT)                    /* safety check */
+    return (linenr_T)0;
+
+  n = lnum + (dp->df_lnum[i] - dp->df_lnum[idx]);
+  if (n > dp->df_lnum[i] + dp->df_count[i])
+    n = dp->df_lnum[i] + dp->df_count[i];
+  return n;
+}
+