1 files changed, 31 insertions, 9 deletions

diff --git a/src/nvim/move.c b/src/nvim/move.c
index a5383202a3..c080cf6691 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -1238,7 +1238,7 @@ bool scrolldown(long line_count, int byfold)
   }
 
   if (curwin->w_cursor.lnum == curwin->w_topline && do_sms) {
-    long so = curwin->w_p_so >= 0 ? curwin->w_p_so : p_so;
+    long so = get_scrolloff_value(curwin);
     long scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
 
     // make sure the cursor is in the visible text
@@ -1274,12 +1274,11 @@ bool scrollup(long line_count, int byfold)
   if (do_sms || (byfold && hasAnyFolding(curwin)) || win_may_fill(curwin)) {
     int width1 = curwin->w_width - curwin_col_off();
     int width2 = width1 + curwin_col_off2();
-    int size = 0;
+    unsigned size = 0;
     linenr_T prev_topline = curwin->w_topline;
 
     if (do_sms) {
-      size = (int)win_linetabsize(curwin, curwin->w_topline,
-                                  ml_get(curwin->w_topline), (colnr_T)MAXCOL);
+      size = linetabsize(curwin, curwin->w_topline);
     }
 
     // diff mode: first consume "topfill"
@@ -1300,7 +1299,7 @@ bool scrollup(long line_count, int byfold)
           // the end of the line, then advance to the next line.
           int add = curwin->w_skipcol > 0 ? width2 : width1;
           curwin->w_skipcol += add;
-          if (curwin->w_skipcol >= size) {
+          if ((unsigned)curwin->w_skipcol >= size) {
             if (lnum == curbuf->b_ml.ml_line_count) {
               // at the last screen line, can't scroll further
               curwin->w_skipcol -= add;
@@ -1322,8 +1321,7 @@ bool scrollup(long line_count, int byfold)
           curwin->w_topfill = win_get_fill(curwin, lnum);
           curwin->w_skipcol = 0;
           if (todo > 1 && do_sms) {
-            size = (int)win_linetabsize(curwin, curwin->w_topline,
-                                        ml_get(curwin->w_topline), (colnr_T)MAXCOL);
+            size = linetabsize(curwin, curwin->w_topline);
           }
         }
       }
@@ -1363,11 +1361,16 @@ bool scrollup(long line_count, int byfold)
   if (curwin->w_cursor.lnum == curwin->w_topline && do_sms && curwin->w_skipcol > 0) {
     int width1 = curwin->w_width - curwin_col_off();
     int width2 = width1 + curwin_col_off2();
-    long so = curwin->w_p_so >= 0 ? curwin->w_p_so : p_so;
+    long so = get_scrolloff_value(curwin);
     long scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
+    int space_cols = (curwin->w_height - 1) * width2;
 
     // Make sure the cursor is in a visible part of the line, taking
     // 'scrolloff' into account, but using screen lines.
+    // If there are not enough screen lines put the cursor in the middle.
+    if (scrolloff_cols > space_cols / 2) {
+      scrolloff_cols = space_cols / 2;
+    }
     validate_virtcol();
     if (curwin->w_virtcol < curwin->w_skipcol + 3 + scrolloff_cols) {
       colnr_T col = curwin->w_virtcol;
@@ -1402,11 +1405,20 @@ void adjust_skipcol(void)
 
   int width1 = curwin->w_width - curwin_col_off();
   int width2 = width1 + curwin_col_off2();
-  long so = curwin->w_p_so >= 0 ? curwin->w_p_so : p_so;
+  long so = get_scrolloff_value(curwin);
   long scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
   bool scrolled = false;
 
   validate_virtcol();
+  if (curwin->w_cline_height == curwin->w_height) {
+    // the line just fits in the window, don't scroll
+    if (curwin->w_skipcol != 0) {
+      curwin->w_skipcol = 0;
+      redraw_later(curwin, UPD_NOT_VALID);
+    }
+    return;
+  }
+
   while (curwin->w_skipcol > 0
          && curwin->w_virtcol < curwin->w_skipcol + 3 + scrolloff_cols) {
     // scroll a screen line down
@@ -2071,6 +2083,16 @@ void cursor_correct(void)
     return;
   }
 
+  if (curwin->w_p_sms && !curwin->w_p_wrap) {
+    // 'smoothscroll is active
+    if (curwin->w_cline_height == curwin->w_height) {
+      // The cursor line just fits in the window, don't scroll.
+      curwin->w_skipcol = 0;
+      return;
+    }
+    // TODO(vim): If the cursor line doesn't fit in the window then only adjust w_skipcol.
+  }
+
   // Narrow down the area where the cursor can be put by taking lines from
   // the top and the bottom until:
   // - the desired context lines are found