Merge pull request #28044 from luukvbaal/vim-9.1.0211

vim-patch:9.1.{0211,0215}

13 files changed, 213 insertions, 434 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 3cc5b6af64..b0583d306d 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -5693,8 +5693,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	highlighted with |hl-NonText|.
 	You may also want to add "lastline" to the 'display' option to show as
 	much of the last line as possible.
-	NOTE: only partly implemented, currently works with CTRL-E, CTRL-Y
-	and scrolling with the mouse.
+	NOTE: only partly implemented, currently works with CTRL-E, CTRL-Y,
+	CTRL-D, CTRL-U, CTRL-F, CTRL-B and scrolling with the mouse.
 
 						*'softtabstop'* *'sts'*
 'softtabstop' 'sts'	number	(default 0)
@@ -7164,8 +7164,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	will scroll 'window' minus two lines, with a minimum of one.
 	When 'window' is equal to 'lines' minus one CTRL-F and CTRL-B scroll
 	in a much smarter way, taking care of wrapping lines.
-	When resizing the Vim window, the value is smaller than 1 or more than
-	or equal to 'lines' it will be set to 'lines' minus 1.
+	When resizing the Vim window, and the value is smaller than 1 or more
+	than or equal to 'lines' it will be set to 'lines' minus 1.
 	Note: Do not confuse this with the height of the Vim window, use
 	'lines' for that.
 
diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index e8e56e86b2..adc42f9659 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -6075,8 +6075,8 @@ vim.go.sta = vim.go.smarttab
 --- highlighted with `hl-NonText`.
 --- You may also want to add "lastline" to the 'display' option to show as
 --- much of the last line as possible.
---- NOTE: only partly implemented, currently works with CTRL-E, CTRL-Y
---- and scrolling with the mouse.
+--- NOTE: only partly implemented, currently works with CTRL-E, CTRL-Y,
+--- CTRL-D, CTRL-U, CTRL-F, CTRL-B and scrolling with the mouse.
 ---
 --- @type boolean
 vim.o.smoothscroll = false
@@ -7861,8 +7861,8 @@ vim.wo.winbl = vim.wo.winblend
 --- will scroll 'window' minus two lines, with a minimum of one.
 --- When 'window' is equal to 'lines' minus one CTRL-F and CTRL-B scroll
 --- in a much smarter way, taking care of wrapping lines.
---- When resizing the Vim window, the value is smaller than 1 or more than
---- or equal to 'lines' it will be set to 'lines' minus 1.
+--- When resizing the Vim window, and the value is smaller than 1 or more
+--- than or equal to 'lines' it will be set to 'lines' minus 1.
 --- Note: Do not confuse this with the height of the Vim window, use
 --- 'lines' for that.
 ---
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 8e9649b6b1..8b8345657c 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -4192,7 +4192,7 @@ static void ins_pageup(void)
   }
 
   pos_T tpos = curwin->w_cursor;
-  if (onepage(BACKWARD, 1) == OK) {
+  if (pagescroll(BACKWARD, 1, false) == OK) {
     start_arrow(&tpos);
     can_cindent = true;
   } else {
@@ -4237,7 +4237,7 @@ static void ins_pagedown(void)
   }
 
   pos_T tpos = curwin->w_cursor;
-  if (onepage(FORWARD, 1) == OK) {
+  if (pagescroll(FORWARD, 1, false) == OK) {
     start_arrow(&tpos);
     can_cindent = true;
   } else {
diff --git a/src/nvim/mouse.c b/src/nvim/mouse.c
index a2b4042f30..1e70462700 100644
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -1024,7 +1024,7 @@ void do_mousescroll(cmdarg_T *cap)
     // Vertical scrolling
     if ((State & MODE_NORMAL) && shift_or_ctrl) {
       // whole page up or down
-      onepage(cap->arg ? FORWARD : BACKWARD, 1);
+      pagescroll(cap->arg ? FORWARD : BACKWARD, 1, false);
     } else {
       if (shift_or_ctrl) {
         // whole page up or down
diff --git a/src/nvim/move.c b/src/nvim/move.c
index 3c4da7f8ac..52b65c0fef 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -36,6 +36,7 @@
 #include "nvim/message.h"
 #include "nvim/mouse.h"
 #include "nvim/move.h"
+#include "nvim/normal.h"
 #include "nvim/option.h"
 #include "nvim/option_vars.h"
 #include "nvim/plines.h"
@@ -1552,21 +1553,6 @@ void check_topfill(win_T *wp, bool down)
   win_check_anchored_floats(wp);
 }
 
-// Use as many filler lines as possible for w_topline.  Make sure w_topline
-// is still visible.
-static void max_topfill(void)
-{
-  int n = plines_win_nofill(curwin, curwin->w_topline, true);
-  if (n >= curwin->w_height_inner) {
-    curwin->w_topfill = 0;
-  } else {
-    curwin->w_topfill = win_get_fill(curwin, curwin->w_topline);
-    if (curwin->w_topfill + n > curwin->w_height_inner) {
-      curwin->w_topfill = curwin->w_height_inner - n;
-    }
-  }
-}
-
 // Scroll the screen one line down, but don't do it if it would move the
 // cursor off the screen.
 void scrolldown_clamp(void)
@@ -1697,28 +1683,6 @@ static void botline_forw(win_T *wp, lineoff_T *lp)
   }
 }
 
-// Switch from including filler lines below lp->lnum to including filler
-// lines above loff.lnum + 1.  This keeps pointing to the same line.
-// When there are no filler lines nothing changes.
-static void botline_topline(lineoff_T *lp)
-{
-  if (lp->fill > 0) {
-    lp->lnum++;
-    lp->fill = win_get_fill(curwin, lp->lnum) - lp->fill + 1;
-  }
-}
-
-// Switch from including filler lines above lp->lnum to including filler
-// lines below loff.lnum - 1.  This keeps pointing to the same line.
-// When there are no filler lines nothing changes.
-static void topline_botline(lineoff_T *lp)
-{
-  if (lp->fill > 0) {
-    lp->fill = win_get_fill(curwin, lp->lnum) - lp->fill + 1;
-    lp->lnum--;
-  }
-}
-
 // Recompute topline to put the cursor at the top of the window.
 // Scroll at least "min_scroll" lines.
 // If "always" is true, always set topline (for "zt").
@@ -2314,371 +2278,127 @@ void cursor_correct(win_T *wp)
   wp->w_viewport_invalid = true;
 }
 
-/// Move screen "count" pages up ("dir" is BACKWARD) or down ("dir" is FORWARD)
-/// and update the screen.
+/// Decide how much overlap to use for page-up or page-down scrolling.
+/// This is symmetric, so that doing both keeps the same lines displayed.
+/// Three lines are examined:
 ///
-/// @return  FAIL for failure, OK otherwise.
-int onepage(Direction dir, int count)
+///  before CTRL-F          after CTRL-F / before CTRL-B
+///     etc.                    l1
+///  l1 last but one line       ------------
+///  l2 last text line          l2 top text line
+///  -------------              l3 second text line
+///  l3                            etc.
+static int get_scroll_overlap(Direction dir)
 {
-  int retval = OK;
   lineoff_T loff;
-  linenr_T old_topline = curwin->w_topline;
-  int so = get_scrolloff_value(curwin);
-
-  if (curbuf->b_ml.ml_line_count == 1) {    // nothing to do
-    beep_flush();
-    return FAIL;
-  }
-
-  for (; count > 0; count--) {
-    validate_botline(curwin);
-    // It's an error to move a page up when the first line is already on
-    // the screen. It's an error to move a page down when the last line
-    // is on the screen and the topline is 'scrolloff' lines from the
-    // last line.
-    if (dir == FORWARD
-        ? ((curwin->w_topline >= curbuf->b_ml.ml_line_count - so)
-           && curwin->w_botline > curbuf->b_ml.ml_line_count)
-        : (curwin->w_topline == 1
-           && curwin->w_topfill == win_get_fill(curwin, curwin->w_topline))) {
-      beep_flush();
-      retval = FAIL;
-      break;
-    }
-
-    loff.fill = 0;
-    if (dir == FORWARD) {
-      if (ONE_WINDOW && p_window > 0 && p_window < Rows - 1) {
-        // Vi compatible scrolling
-        if (p_window <= 2) {
-          curwin->w_topline++;
-        } else {
-          curwin->w_topline += (linenr_T)p_window - 2;
-        }
-        if (curwin->w_topline > curbuf->b_ml.ml_line_count) {
-          curwin->w_topline = curbuf->b_ml.ml_line_count;
-        }
-        curwin->w_cursor.lnum = curwin->w_topline;
-      } else if (curwin->w_botline > curbuf->b_ml.ml_line_count) {
-        // at end of file
-        curwin->w_topline = curbuf->b_ml.ml_line_count;
-        curwin->w_topfill = 0;
-        curwin->w_valid &= ~(VALID_WROW|VALID_CROW);
-      } else {
-        // For the overlap, start with the line just below the window
-        // and go upwards.
-        loff.lnum = curwin->w_botline;
-        loff.fill = win_get_fill(curwin, loff.lnum)
-                    - curwin->w_filler_rows;
-        get_scroll_overlap(&loff, -1);
-        curwin->w_topline = loff.lnum;
-        curwin->w_topfill = loff.fill;
-        check_topfill(curwin, false);
-        curwin->w_cursor.lnum = curwin->w_topline;
-        curwin->w_valid &= ~(VALID_WCOL|VALID_CHEIGHT|VALID_WROW|
-                             VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
-      }
-    } else {  // dir == BACKWARDS
-      if (curwin->w_topline == 1) {
-        // Include max number of filler lines
-        max_topfill();
-        continue;
-      }
-      if (ONE_WINDOW && p_window > 0 && p_window < Rows - 1) {
-        // Vi compatible scrolling (sort of)
-        if (p_window <= 2) {
-          curwin->w_topline--;
-        } else {
-          curwin->w_topline -= (linenr_T)p_window - 2;
-        }
-        if (curwin->w_topline < 1) {
-          curwin->w_topline = 1;
-        }
-        curwin->w_cursor.lnum = curwin->w_topline + (linenr_T)p_window - 1;
-        if (curwin->w_cursor.lnum > curbuf->b_ml.ml_line_count) {
-          curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
-        }
-        continue;
-      }
-
-      // Find the line at the top of the window that is going to be the
-      // line at the bottom of the window.  Make sure this results in
-      // the same line as before doing CTRL-F.
-      loff.lnum = curwin->w_topline - 1;
-      loff.fill = win_get_fill(curwin, loff.lnum + 1) - curwin->w_topfill;
-      get_scroll_overlap(&loff, 1);
-
-      if (loff.lnum >= curbuf->b_ml.ml_line_count) {
-        loff.lnum = curbuf->b_ml.ml_line_count;
-        loff.fill = 0;
-      } else {
-        botline_topline(&loff);
-      }
-      curwin->w_cursor.lnum = loff.lnum;
+  int min_height = curwin->w_height_inner - 2;
 
-      // Find the line just above the new topline to get the right line
-      // at the bottom of the window.
-      int n = 0;
-      while (n <= curwin->w_height_inner && loff.lnum >= 1) {
-        topline_back(curwin, &loff);
-        if (loff.height == MAXCOL) {
-          n = MAXCOL;
-        } else {
-          n += loff.height;
-        }
-      }
-      if (loff.lnum < 1) {                      // at begin of file
-        curwin->w_topline = 1;
-        max_topfill();
-        curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-      } else {
-        // Go two lines forward again.
-        topline_botline(&loff);
-        botline_forw(curwin, &loff);
-        botline_forw(curwin, &loff);
-        botline_topline(&loff);
-        // We're at the wrong end of a fold now.
-        hasFolding(curwin, loff.lnum, &loff.lnum, NULL);
-
-        // Always scroll at least one line.  Avoid getting stuck on
-        // very long lines.
-        if (loff.lnum >= curwin->w_topline
-            && (loff.lnum > curwin->w_topline
-                || loff.fill >= curwin->w_topfill)) {
-          // First try using the maximum number of filler lines.  If
-          // that's not enough, backup one line.
-          loff.fill = curwin->w_topfill;
-          if (curwin->w_topfill < win_get_fill(curwin, curwin->w_topline)) {
-            max_topfill();
-          }
-          if (curwin->w_topfill == loff.fill) {
-            curwin->w_topline--;
-            curwin->w_topfill = 0;
-            curwin->w_valid &= ~(VALID_WROW|VALID_CROW);
-          }
-          comp_botline(curwin);
-          curwin->w_cursor.lnum = curwin->w_botline - 1;
-          curwin->w_valid &= ~(VALID_WCOL|VALID_CHEIGHT|VALID_WROW|VALID_CROW);
-        } else {
-          curwin->w_topline = loff.lnum;
-          curwin->w_topfill = loff.fill;
-          check_topfill(curwin, false);
-          curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-        }
-      }
-    }
-  }
-  foldAdjustCursor(curwin);
-  cursor_correct(curwin);
-  check_cursor_col(curwin);
-  if (retval == OK) {
-    beginline(BL_SOL | BL_FIX);
-  }
-  curwin->w_valid &= ~(VALID_WCOL|VALID_WROW|VALID_VIRTCOL);
-
-  if (retval == OK && dir == FORWARD) {
-    // Avoid the screen jumping up and down when 'scrolloff' is non-zero.
-    // But make sure we scroll at least one line (happens with mix of long
-    // wrapping lines and non-wrapping line).
-    if (check_top_offset()) {
-      scroll_cursor_top(curwin, 1, false);
-      if (curwin->w_topline <= old_topline
-          && old_topline < curbuf->b_ml.ml_line_count) {
-        curwin->w_topline = old_topline + 1;
-        hasFolding(curwin, curwin->w_topline, &curwin->w_topline, NULL);
-      }
-    } else if (curwin->w_botline > curbuf->b_ml.ml_line_count) {
-      hasFolding(curwin, curwin->w_topline, &curwin->w_topline, NULL);
-    }
+  validate_botline(curwin);
+  if (dir == FORWARD && curwin->w_botline > curbuf->b_ml.ml_line_count) {
+    return min_height + 2;  // no overlap, still handle 'smoothscroll'
   }
 
-  redraw_later(curwin, UPD_VALID);
-  return retval;
-}
-
-// Decide how much overlap to use for page-up or page-down scrolling.
-// This is symmetric, so that doing both keeps the same lines displayed.
-// Three lines are examined:
-//
-//  before CTRL-F           after CTRL-F / before CTRL-B
-//     etc.                     l1
-//  l1 last but one line        ------------
-//  l2 last text line           l2 top text line
-//  -------------               l3 second text line
-//  l3                             etc.
-static void get_scroll_overlap(lineoff_T *lp, int dir)
-{
-  int min_height = curwin->w_height_inner - 2;
+  loff.lnum = dir == FORWARD ? curwin->w_botline : curwin->w_topline - 1;
+  loff.fill = win_get_fill(curwin, loff.lnum + dir == BACKWARD)
+              - (dir == FORWARD ? curwin->w_filler_rows : curwin->w_topfill);
+  loff.height = loff.fill > 0 ? 1 : plines_win_nofill(curwin, loff.lnum, true);
 
-  if (lp->fill > 0) {
-    lp->height = 1;
-  } else {
-    lp->height = plines_win_nofill(curwin, lp->lnum, true);
-  }
-  int h1 = lp->height;
+  int h1 = loff.height;
   if (h1 > min_height) {
-    return;             // no overlap
+    return min_height + 2;  // no overlap
   }
-  lineoff_T loff0 = *lp;
-  if (dir > 0) {
-    botline_forw(curwin, lp);
+  if (dir == FORWARD) {
+    topline_back(curwin, &loff);
   } else {
-    topline_back(curwin, lp);
+    botline_forw(curwin, &loff);
   }
-  int h2 = lp->height;
+
+  int h2 = loff.height;
   if (h2 == MAXCOL || h2 + h1 > min_height) {
-    *lp = loff0;        // no overlap
-    return;
+    return min_height + 2;  // no overlap
   }
-
-  lineoff_T loff1 = *lp;
-  if (dir > 0) {
-    botline_forw(curwin, lp);
+  if (dir == FORWARD) {
+    topline_back(curwin, &loff);
   } else {
-    topline_back(curwin, lp);
+    botline_forw(curwin, &loff);
   }
-  int h3 = lp->height;
+
+  int h3 = loff.height;
   if (h3 == MAXCOL || h3 + h2 > min_height) {
-    *lp = loff0;        // no overlap
-    return;
+    return min_height + 2;  // no overlap
   }
-
-  lineoff_T loff2 = *lp;
-  if (dir > 0) {
-    botline_forw(curwin, lp);
+  if (dir == FORWARD) {
+    topline_back(curwin, &loff);
   } else {
-    topline_back(curwin, lp);
+    botline_forw(curwin, &loff);
   }
-  int h4 = lp->height;
+
+  int h4 = loff.height;
   if (h4 == MAXCOL || h4 + h3 + h2 > min_height || h3 + h2 + h1 > min_height) {
-    *lp = loff1;        // 1 line overlap
+    return min_height + 1;  // 1 line overlap
   } else {
-    *lp = loff2;        // 2 lines overlap
+    return min_height;      // 2 lines overlap
   }
 }
 
-// Scroll 'scroll' lines up or down.
-void halfpage(bool flag, linenr_T Prenum)
+/// Move screen "count" pages up ("dir" is BACKWARD) or down ("dir" is FORWARD)
+/// and update the screen.
+///
+/// @return  FAIL for failure, OK otherwise.
+int pagescroll(Direction dir, int count, bool half)
 {
-  int scrolled = 0;
-  int i;
-
-  if (Prenum) {
-    curwin->w_p_scr = (Prenum > curwin->w_height_inner) ? curwin->w_height_inner
-                                                        : Prenum;
-  }
-  assert(curwin->w_p_scr <= INT_MAX);
-  int n = curwin->w_p_scr <= curwin->w_height_inner ? (int)curwin->w_p_scr
-                                                    : curwin->w_height_inner;
-
-  update_topline(curwin);
-  validate_botline(curwin);
-  int room = curwin->w_empty_rows + curwin->w_filler_rows;
-  if (flag) {
-    // scroll the text up
-    while (n > 0 && curwin->w_botline <= curbuf->b_ml.ml_line_count) {
-      if (curwin->w_topfill > 0) {
-        i = 1;
-        n--;
-        curwin->w_topfill--;
-      } else {
-        i = plines_win_nofill(curwin, curwin->w_topline, true);
-        n -= i;
-        if (n < 0 && scrolled > 0) {
-          break;
-        }
-        hasFolding(curwin, curwin->w_topline, NULL, &curwin->w_topline);
-        curwin->w_topline++;
-        curwin->w_topfill = win_get_fill(curwin, curwin->w_topline);
-
-        if (curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count) {
-          curwin->w_cursor.lnum++;
-          curwin->w_valid &=
-            ~(VALID_VIRTCOL|VALID_CHEIGHT|VALID_WCOL);
-        }
-      }
-      curwin->w_valid &= ~(VALID_CROW|VALID_WROW);
-      scrolled += i;
+  int prev_topfill = curwin->w_topfill;
+  linenr_T prev_topline = curwin->w_topline;
+  colnr_T prev_skipcol = curwin->w_skipcol;
 
-      // Correct w_botline for changed w_topline.
-      // Won't work when there are filler lines.
-      if (win_may_fill(curwin)) {
-        curwin->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
-      } else {
-        room += i;
-        do {
-          i = plines_win(curwin, curwin->w_botline, true);
-          if (i > room) {
-            break;
-          }
-          hasFolding(curwin, curwin->w_botline, NULL, &curwin->w_botline);
-          curwin->w_botline++;
-          room -= i;
-        } while (curwin->w_botline <= curbuf->b_ml.ml_line_count);
-      }
+  if (half) {
+    // Scroll [count], 'scroll' or current window height lines.
+    if (count) {
+      curwin->w_p_scr = MIN(curwin->w_height_inner, count);
     }
+    count = MIN(curwin->w_height_inner, (int)curwin->w_p_scr);
+  } else {
+    // Scroll 'window' or current window height lines.
+    count *= ((ONE_WINDOW && p_window > 0 && p_window < Rows - 1)
+              ? (int)p_window - 2 : get_scroll_overlap(dir));
+  }
 
-    // When hit bottom of the file: move cursor down.
-    if (n > 0) {
-      if (hasAnyFolding(curwin)) {
-        while (--n >= 0
-               && curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count) {
-          hasFolding(curwin, curwin->w_cursor.lnum, NULL,
-                     &curwin->w_cursor.lnum);
-          curwin->w_cursor.lnum++;
-        }
-      } else {
-        curwin->w_cursor.lnum += n;
-      }
-      check_cursor_lnum(curwin);
-    }
+  if (curwin->w_p_sms) {
+    scroll_redraw(dir == FORWARD, count);
   } else {
-    // scroll the text down
-    while (n > 0 && curwin->w_topline > 1) {
-      if (curwin->w_topfill < win_get_fill(curwin, curwin->w_topline)) {
-        i = 1;
-        n--;
-        curwin->w_topfill++;
-      } else {
-        i = plines_win_nofill(curwin, curwin->w_topline - 1, true);
-        n -= i;
-        if (n < 0 && scrolled > 0) {
-          break;
-        }
-        curwin->w_topline--;
-        hasFolding(curwin, curwin->w_topline, &curwin->w_topline, NULL);
-        curwin->w_topfill = 0;
-      }
-      curwin->w_valid &= ~(VALID_CROW|VALID_WROW|
-                           VALID_BOTLINE|VALID_BOTLINE_AP);
-      scrolled += i;
-      if (curwin->w_cursor.lnum > 1) {
-        curwin->w_cursor.lnum--;
-        curwin->w_valid &= ~(VALID_VIRTCOL|VALID_CHEIGHT|VALID_WCOL);
-      }
-    }
+    // Scroll at least one full line without 'smoothscroll'.
+    count -= plines_win_nofill(curwin, curwin->w_topline, false);
+    scroll_redraw(dir == FORWARD, 1);
 
-    // When hit top of the file: move cursor up.
-    if (n > 0) {
-      if (curwin->w_cursor.lnum <= (linenr_T)n) {
-        curwin->w_cursor.lnum = 1;
-      } else if (hasAnyFolding(curwin)) {
-        while (--n >= 0 && curwin->w_cursor.lnum > 1) {
-          curwin->w_cursor.lnum--;
-          hasFolding(curwin, curwin->w_cursor.lnum,
-                     &curwin->w_cursor.lnum, NULL);
-        }
-      } else {
-        curwin->w_cursor.lnum -= n;
-      }
+    // Temporarily set 'smoothscroll' so that scrolling count lines
+    // does not skip over parts of the buffer with wrapped lines.
+    curwin->w_p_sms = true;
+    if (count > 0) {
+      scroll_redraw(dir == FORWARD, count);
     }
+    curwin->w_p_sms = false;
   }
   // Move cursor to first line of closed fold.
   foldAdjustCursor(curwin);
-  check_topfill(curwin, !flag);
-  cursor_correct(curwin);
-  beginline(BL_SOL | BL_FIX);
-  redraw_later(curwin, UPD_VALID);
+
+  int nochange = curwin->w_topline == prev_topline
+                 && curwin->w_topfill == prev_topfill
+                 && curwin->w_skipcol == prev_skipcol;
+
+  // Error if the viewport did not change and the cursor is already
+  // at the boundary.
+  if (nochange) {
+    int prev_cursor = curwin->w_cursor.lnum;
+    curwin->w_cursor.lnum += (count + 1) * (dir == FORWARD ? 1 : -1);
+    check_cursor(curwin);
+    if (curwin->w_cursor.lnum == prev_cursor) {
+      beep_flush();
+    }
+  } else if (!curwin->w_p_sms || curwin->w_skipcol == prev_skipcol) {
+    beginline(BL_SOL | BL_FIX);
+  }
+
+  return nochange;
 }
 
 void do_check_cursorbind(void)
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 12f0bb631e..bbba8069c7 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -2258,7 +2258,7 @@ static void nv_page(cmdarg_T *cap)
       goto_tabpage(cap->count0);
     }
   } else {
-    onepage(cap->arg, cap->count1);
+    pagescroll(cap->arg, cap->count1, false);
   }
 }
 
@@ -6394,12 +6394,8 @@ static void nv_at(cmdarg_T *cap)
 /// Handle the CTRL-U and CTRL-D commands.
 static void nv_halfpage(cmdarg_T *cap)
 {
-  if ((cap->cmdchar == Ctrl_U && curwin->w_cursor.lnum == 1)
-      || (cap->cmdchar == Ctrl_D
-          && curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count)) {
-    clearopbeep(cap->oap);
-  } else if (!checkclearop(cap->oap)) {
-    halfpage(cap->cmdchar == Ctrl_D, cap->count0);
+  if (!checkclearop(cap->oap)) {
+    pagescroll(cap->cmdchar == Ctrl_D, cap->count0, true);
   }
 }
 
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index 6bfeee75e6..e7acf6f6ef 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -7663,8 +7663,8 @@ return {
         highlighted with |hl-NonText|.
         You may also want to add "lastline" to the 'display' option to show as
         much of the last line as possible.
-        NOTE: only partly implemented, currently works with CTRL-E, CTRL-Y
-        and scrolling with the mouse.
+        NOTE: only partly implemented, currently works with CTRL-E, CTRL-Y,
+        CTRL-D, CTRL-U, CTRL-F, CTRL-B and scrolling with the mouse.
       ]=],
       full_name = 'smoothscroll',
       pv_name = 'p_sms',
@@ -9806,8 +9806,8 @@ return {
         will scroll 'window' minus two lines, with a minimum of one.
         When 'window' is equal to 'lines' minus one CTRL-F and CTRL-B scroll
         in a much smarter way, taking care of wrapping lines.
-        When resizing the Vim window, the value is smaller than 1 or more than
-        or equal to 'lines' it will be set to 'lines' minus 1.
+        When resizing the Vim window, and the value is smaller than 1 or more
+        than or equal to 'lines' it will be set to 'lines' minus 1.
         Note: Do not confuse this with the height of the Vim window, use
         'lines' for that.
       ]=],
diff --git a/test/functional/legacy/matchparen_spec.lua b/test/functional/legacy/matchparen_spec.lua
index 7b3f7bd424..adbf15d2e3 100644
--- a/test/functional/legacy/matchparen_spec.lua
+++ b/test/functional/legacy/matchparen_spec.lua
@@ -19,7 +19,7 @@ describe('matchparen', function()
       call cursor(5, 1)
     ]])
 
-    feed('V<c-d><c-d>')
+    feed('V<c-d><c-d>3j')
     screen:expect([[
       {17:{}                             |
       {17:}}                             |
diff --git a/test/functional/legacy/scroll_opt_spec.lua b/test/functional/legacy/scroll_opt_spec.lua
index 78028f2f44..c00993f5f7 100644
--- a/test/functional/legacy/scroll_opt_spec.lua
+++ b/test/functional/legacy/scroll_opt_spec.lua
@@ -740,7 +740,7 @@ describe('smoothscroll', function()
                                               |
     ]])
     exec("call setline(92, 'a'->repeat(100))")
-    feed('<C-B>G')
+    feed('<C-L><C-B>G')
     -- cursor is not placed below window
     screen:expect([[
       {1:<<<}aaaaaaaaaaaaaaaaa                    |
diff --git a/test/old/testdir/test_diffmode.vim b/test/old/testdir/test_diffmode.vim
index c1a63a6f88..3e7eabf8f5 100644
--- a/test/old/testdir/test_diffmode.vim
+++ b/test/old/testdir/test_diffmode.vim
@@ -1632,34 +1632,38 @@ endfunc
 func Test_diff_scroll_many_filler()
   20new
   vnew
-  call setline(1, ['^^^', '^^^', '$$$', '$$$'])
+  call setline(1, range(1, 40))
   diffthis
   setlocal scrolloff=0
   wincmd p
-  call setline(1, ['^^^', '^^^'] + repeat(['###'], 41) + ['$$$', '$$$'])
+  call setline(1, range(1, 20)->reverse() + ['###']->repeat(41) + range(21, 40)->reverse())
   diffthis
   setlocal scrolloff=0
   wincmd p
   redraw
 
   " Note: need a redraw after each scroll, otherwise the test always passes.
-  normal! G
-  redraw
-  call assert_equal(3, winsaveview().topline)
-  call assert_equal(18, winsaveview().topfill)
-  exe "normal! \<C-B>"
-  redraw
-  call assert_equal(3, winsaveview().topline)
-  call assert_equal(19, winsaveview().topfill)
-  exe "normal! \<C-B>"
-  redraw
-  call assert_equal(2, winsaveview().topline)
-  call assert_equal(0, winsaveview().topfill)
-  exe "normal! \<C-B>"
-  redraw
-  call assert_equal(1, winsaveview().topline)
-  call assert_equal(0, winsaveview().topfill)
+  for _ in range(2)
+    normal! G
+    redraw
+    call assert_equal(40, winsaveview().topline)
+    call assert_equal(19, winsaveview().topfill)
+    exe "normal! \<C-B>"
+    redraw
+    call assert_equal(22, winsaveview().topline)
+    call assert_equal(0, winsaveview().topfill)
+    exe "normal! \<C-B>"
+    redraw
+    call assert_equal(4, winsaveview().topline)
+    call assert_equal(0, winsaveview().topfill)
+    exe "normal! \<C-B>"
+    redraw
+    call assert_equal(1, winsaveview().topline)
+    call assert_equal(0, winsaveview().topfill)
+    set smoothscroll
+  endfor
 
+  set smoothscroll&
   bwipe!
   bwipe!
 endfunc
diff --git a/test/old/testdir/test_edit.vim b/test/old/testdir/test_edit.vim
index 1e12e2341d..1bfe46c4a9 100644
--- a/test/old/testdir/test_edit.vim
+++ b/test/old/testdir/test_edit.vim
@@ -1318,9 +1318,9 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
   call assert_equal([0, 13, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 5, 1, 0], getpos('.'))
+  call assert_equal([0, 10, 1, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 5, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   " <S-Up> is the same as <PageUp>
   " <S-Down> is the same as <PageDown>
   call cursor(1, 1)
@@ -1341,9 +1341,9 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
   call assert_equal([0, 13, 1, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 5, 1, 0], getpos('.'))
+  call assert_equal([0, 10, 1, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 5, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   set nostartofline
   call cursor(30, 11)
   norm! zt
@@ -1354,9 +1354,9 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
   call assert_equal([0, 13, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 5, 11, 0], getpos('.'))
+  call assert_equal([0, 10, 11, 0], getpos('.'))
   call feedkeys("A\<PageUp>\<esc>", 'tnix')
-  call assert_equal([0, 5, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   call cursor(1, 1)
   call feedkeys("A\<PageDown>\<esc>", 'tnix')
   call assert_equal([0, 9, 11, 0], getpos('.'))
@@ -1379,9 +1379,9 @@ func Test_edit_PAGEUP_PAGEDOWN()
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
   call assert_equal([0, 13, 11, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 5, 11, 0], getpos('.'))
+  call assert_equal([0, 10, 11, 0], getpos('.'))
   call feedkeys("A\<S-Up>\<esc>", 'tnix')
-  call assert_equal([0, 5, 11, 0], getpos('.'))
+  call assert_equal([0, 2, 11, 0], getpos('.'))
   call cursor(1, 1)
   call feedkeys("A\<S-Down>\<esc>", 'tnix')
   call assert_equal([0, 9, 11, 0], getpos('.'))
diff --git a/test/old/testdir/test_normal.vim b/test/old/testdir/test_normal.vim
index d31ae488d9..937f18aa69 100644
--- a/test/old/testdir/test_normal.vim
+++ b/test/old/testdir/test_normal.vim
@@ -131,7 +131,7 @@ func Test_normal01_keymodel()
   call assert_equal([0, 1, 1, 0], getpos("'<"))
   call assert_equal([0, 3, 1, 0], getpos("'>"))
   call feedkeys("Gz\<CR>8|\<S-PageUp>y", 'xt')
-  call assert_equal([0, 2, 1, 0], getpos("'<"))
+  call assert_equal([0, 3, 1, 0], getpos("'<"))
   call assert_equal([0, 3, 8, 0], getpos("'>"))
   " Test for <S-C-Home> and <S-C-End>
   call cursor(2, 12)
@@ -915,12 +915,10 @@ func Test_normal14_page()
   set scrolloff=0
   100
   exe "norm! $\<c-b>"
-  call assert_equal('92', getline('.'))
   call assert_equal([0, 92, 1, 0, 1], getcurpos())
   100
   set nostartofline
   exe "norm! $\<c-b>"
-  call assert_equal('92', getline('.'))
   call assert_equal([0, 92, 2, 0, v:maxcol], getcurpos())
   " cleanup
   set startofline
@@ -1285,9 +1283,13 @@ func Test_vert_scroll_cmds()
   exe "normal \<C-D>"
   call assert_equal(46, line('.'))
   exe "normal \<C-U>"
-  call assert_equal(36, line('.'))
+  call assert_equal(36, line('w0'))
+  call assert_equal(46, line('.'))
   exe "normal \<C-U>"
-  call assert_equal(10, line('.'))
+  call assert_equal(1,  line('w0'))
+  call assert_equal(40, line('.'))
+  exe "normal \<C-U>"
+  call assert_equal(30, line('.'))
   exe "normal \<C-U>"
   call assert_equal(1, line('.'))
   set scroll&
@@ -1308,9 +1310,8 @@ func Test_vert_scroll_cmds()
   call assert_equal(50, line('.'))
   call assert_equal(100, line('w$'))
   normal z.
-  let lnum = winline()
   exe "normal \<C-D>"
-  call assert_equal(lnum, winline())
+  call assert_equal(1, winline())
   call assert_equal(50, line('.'))
   normal zt
   exe "normal \<C-D>"
@@ -3079,7 +3080,8 @@ func Test_normal42_halfpage()
   call assert_equal(2, &scroll)
   set scroll=5
   exe "norm! \<c-u>"
-  call assert_equal('3', getline('.'))
+  call assert_equal('3', getline('w0'))
+  call assert_equal('8', getline('.'))
   1
   set scrolloff=5
   exe "norm! \<c-d>"
@@ -3826,7 +3828,7 @@ func Test_normal_vert_scroll_longline()
   call assert_equal(1, winline())
   exe "normal \<C-B>"
   call assert_equal(10, line('.'))
-  call assert_equal(3, winline())
+  call assert_equal(10, winline())
   exe "normal \<C-B>\<C-B>"
   call assert_equal(5, line('.'))
   call assert_equal(5, winline())
@@ -4182,20 +4184,34 @@ func Test_normal34_zet_large()
   norm! z9765405999999999999
 endfunc
 
-" Test for { and } paragraph movements in a single line
-func Test_brace_single_line()
-  let text =<< trim [DATA]
-    foobar one two three
-  [DATA]
+" Test for { and } paragraph movements and Ctrl-B in buffer with a single line
+func Test_single_line_scroll()
+  CheckFeature textprop
 
   new
-  call setline(1, text)
+  call setline(1, ['foobar one two three'])
+  let vt = 'virt_above'
+  call prop_type_add(vt, {'highlight': 'IncSearch'})
+  call prop_add(1, 0, {'type': vt, 'text': '---', 'text_align': 'above'})
   1
   norm! 0}
 
   call assert_equal([0, 1, 20, 0], getpos('.'))
   norm! {
   call assert_equal([0, 1, 1, 0], getpos('.'))
+
+  " Ctrl-B/Ctrl-U scroll up with hidden "above" virtual text.
+  set smoothscroll
+  exe "normal \<C-E>"
+  call assert_notequal(0, winsaveview().skipcol)
+  exe "normal \<C-B>"
+  call assert_equal(0, winsaveview().skipcol)
+  exe "normal \<C-E>"
+  call assert_notequal(0, winsaveview().skipcol)
+  exe "normal \<C-U>"
+  call assert_equal(0, winsaveview().skipcol)
+
+  set smoothscroll&
   bw!
 endfunc
 
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index 8130f7a1ac..fbc714d9cc 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -832,7 +832,7 @@ func Test_smoothscroll_eob()
   call VerifyScreenDump(buf, 'Test_smooth_eob_1', {})
 
   " cursor is not placed below window
-  call term_sendkeys(buf, ":call setline(92, 'a'->repeat(100))\<CR>\<C-B>G")
+  call term_sendkeys(buf, ":call setline(92, 'a'->repeat(100))\<CR>\<C-L>\<C-B>G")
   call VerifyScreenDump(buf, 'Test_smooth_eob_2', {})
 
   call StopVimInTerminal(buf)
@@ -1001,4 +1001,47 @@ func Test_smoothscroll_textoff_small_winwidth()
   set smoothscroll& number&
 endfunc
 
+func Test_smoothscroll_page()
+  set smoothscroll
+
+  10split | 40vsplit
+  call setline(1, 'abcde '->repeat(150))
+
+  exe "norm! \<C-F>"
+  call assert_equal(400, winsaveview().skipcol)
+  exe "norm! \<C-F>"
+  call assert_equal(800, winsaveview().skipcol)
+  exe "norm! \<C-F>"
+  call assert_equal(880, winsaveview().skipcol)
+  exe "norm! \<C-B>"
+  call assert_equal(480, winsaveview().skipcol)
+  exe "norm! \<C-B>"
+  call assert_equal(80, winsaveview().skipcol)
+  exe "norm! \<C-B>"
+  call assert_equal(0, winsaveview().skipcol)
+
+  exe "norm! \<C-D>"
+  call assert_equal(200, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(400, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(600, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(800, winsaveview().skipcol)
+  exe "norm! \<C-D>"
+  call assert_equal(880, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(680, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(480, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(280, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(80, winsaveview().skipcol)
+  exe "norm! \<C-U>"
+  call assert_equal(0, winsaveview().skipcol)
+
+  set smoothscroll&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab