VI: Fix some display and cursor position bugs... still plenty of bugs

system/vi/vi.c

@@ -284,9 +284,10 @@ static void     vi_exitsubmode(FAR struct vi_s *vi, uint8_t mode);
 
 /* Display management */
 
-static uint16_t vi_wincolumn(FAR struct vi_s *vi, off_t start, off_t end);
+static void     vi_windowpos(FAR struct vi_s *vi, off_t start, off_t end,
+                  uint16_t *pcolumn, off_t *ppos);
 static void     vi_scrollcheck(FAR struct vi_s *vi);
-static void     vi_show(FAR struct vi_s *vi);
+static void     vi_showtext(FAR struct vi_s *vi);
 
 /* Command mode */
 
@@ -1221,18 +1222,19 @@ static void vi_exitsubmode(FAR struct vi_s *vi, uint8_t mode)
  ****************************************************************************/
 
 /****************************************************************************
- * Name: vi_wincolumn
+ * Name: vi_windowpos
  *
  * Description:
  *   Based on the position of the cursor in the text buffer, determine the
- *   display cursor position, performing TAB expansion as necessary.
+ *   horizontal display cursor position, performing TAB expansion as necessary.
  *
  ****************************************************************************/
 
-static uint16_t vi_wincolumn(FAR struct vi_s *vi, off_t start, off_t end)
+static void vi_windowpos(FAR struct vi_s *vi, off_t start, off_t end,
+                         uint16_t *pcolumn, off_t *ppos)
 {
   uint16_t column;
-  off_t offset;
+  off_t pos;
 
   vivdbg("start=%ld end=%ld\n", (long)start, (long)end);
 
@@ -1245,24 +1247,24 @@ static uint16_t vi_wincolumn(FAR struct vi_s *vi, off_t start, off_t end)
       end = vi->textsize;
     }
 
-  /* Loop incrementing the text buffer offset while text buffer offset is
+  /* Loop incrementing the text buffer position while text buffer position
-   * within range.
+   * is within range.
    */
 
-  for (offset = start, column = 0; offset < end; offset++)
+  for (pos = start, column = 0; pos < end; pos++)
     {
-      /* Does this offset point to the newline terminator? */
+      /* Is there a newline terminator at this position? */
 
-      if (vi->text[offset] == '\n')
+      if (vi->text[pos] == '\n')
         {
           /* Yes... break out of the loop return the cursor column */
 
           break;
         }
 
-      /* No... does it refer to a TAB? */
+      /* No... Is there a TAB at this position? */
 
-      else if (vi->text[offset] == '\t')
+      else if (vi->text[pos] == '\t')
         {
           /* Yes.. expand the TAB */
 
@@ -1277,7 +1279,17 @@ static uint16_t vi_wincolumn(FAR struct vi_s *vi, off_t start, off_t end)
         }
     }
 
-  return column;
+  /* Now return the requested values */
+
+  if (ppos)
+    {
+      *ppos = pos;
+    }
+
+  if (pcolumn)
+    {
+      *pcolumn = column;
+    }
 }
 
 /****************************************************************************
@@ -1292,6 +1304,7 @@ static void vi_scrollcheck(FAR struct vi_s *vi)
 {
   off_t curline;
   off_t pos;
+  uint16_t tmp;
   int column;
   int nlines;
 
@@ -1328,12 +1341,13 @@ static void vi_scrollcheck(FAR struct vi_s *vi)
       vi->winpos = vi_nextline(vi, vi->winpos);
     }
 
-  /* Check if the cursor column is on the display.  vi_wincolumn returns the
+  /* Check if the cursor column is on the display.  vi_windowpos returns the
    * unrestricted column number of cursor.  hscroll is the horizontal offset
    * in characters.
    */
 
-  column = (int)vi_wincolumn(vi, curline, vi->curpos) - (int)vi->hscroll;
+  vi_windowpos(vi, curline, vi->curpos, &tmp, NULL);
+  column = (int)tmp - (int)vi->hscroll;
 
   /* Force the cursor column to lie on the display.  First check if the
    * column lies to the left of the horizontal scrolling position.  If it
@@ -1421,7 +1435,7 @@ static void vi_scrollcheck(FAR struct vi_s *vi)
 }
 
 /****************************************************************************
- * Name: vi_show
+ * Name: vi_showtext
  *
  * Description:
  *   Update the display based on the last operation.  This function is
@@ -1430,7 +1444,7 @@ static void vi_scrollcheck(FAR struct vi_s *vi)
  *
  ****************************************************************************/
 
-static void vi_show(FAR struct vi_s *vi)
+static void vi_showtext(FAR struct vi_s *vi)
 {
   off_t pos;
   uint16_t row;
@@ -1477,11 +1491,13 @@ static void vi_show(FAR struct vi_s *vi)
          endcol--;
         }
 
-      /* Get the offset into this line corresponding to column 0, accounting
+      /* Get the position into this line corresponding to display column 0,
-       * for horizontal scrolling and tab expansion.
+       * accounting for horizontal scrolling and tab expansion.  Add that to
+       * the line start offset to get the first offset to consider for
+       * display.
        */
 
-      pos = vi_wincolumn(vi, pos, pos + vi->hscroll);
+      vi_windowpos(vi, pos, pos + vi->hscroll, NULL, &pos);
 
       /* Set the cursor position to the beginning of this row and clear to
        * the end of the line.
@@ -1588,10 +1604,15 @@ static void vi_cusorup(FAR struct vi_s *vi, int nlines)
 
   for (; remaining > 0; remaining--)
     {
+      /* Get the start and end offset of the line */
+
       pos        = vi_prevline(vi, start);
       start      = vi_linebegin(vi, pos);
       end        = start + vi->cursor.column + vi->hscroll;
-      vi->curpos = vi_wincolumn(vi, start, end);
+
+      /* Get the text buffer position to the horizontal cursor position */
+
+      vi_windowpos(vi, start, end, NULL, &vi->curpos);
     }
 }
 
@@ -1628,9 +1649,14 @@ static void vi_cursordown(FAR struct vi_s *vi, int nlines)
           break;
         }
 
+      /* Get the start and end offset of the line */
+
       start = vi_nextline(vi, start);
       end   = start + vi->cursor.column + vi->hscroll;
-      vi->curpos = vi_wincolumn(vi, start, end);
+
+      /* Get the text buffer position to the horizontal cursor position */
+
+      vi_windowpos(vi, start, end, NULL, &vi->curpos);
     }
 }
 
@@ -1897,7 +1923,7 @@ static void vi_cmd_mode(FAR struct vi_s *vi)
     {
       /* Make sure that the display reflects the current state */
 
-      vi_show(vi);
+      vi_showtext(vi);
       vi_setcursor(vi, vi->cursor.row, vi->cursor.column);
 
       /* Get the next character from the input */
@@ -2881,7 +2907,7 @@ static void vi_insert_mode(FAR struct vi_s *vi)
     {
       /* Make sure that the display reflects the current state */
 
-      vi_show(vi);
+      vi_showtext(vi);
       vi_setcursor(vi, vi->cursor.row, vi->cursor.column);
 
       /* Get the next character from the input */
@@ -2996,7 +3022,7 @@ static void vi_replace_mode(FAR struct vi_s *vi)
     {
       /* Make sure that the display reflects the current state */
 
-      vi_show(vi);
+      vi_showtext(vi);
       vi_setcursor(vi, vi->cursor.row, vi->cursor.column);
 
       /* Get the next character from the input */