vi: reduce amount of memset'ing on each screen refresh

1 files changed, 13 insertions, 9 deletions

diff --git a/editors/vi.c b/editors/vi.c
index 65a82b138..f06cad227 100644
--- a/editors/vi.c
+++ b/editors/vi.c
@@ -2516,9 +2516,9 @@ static void place_cursor(int row, int col, int optimize)
                 }
  skip: ;
         }
+        last_row = row;
 #endif /* FEATURE_VI_OPTIMIZE_CURSOR */
         write1(cm);
-        last_row = row;
 }
 
 //----- Erase from cursor to end of line -----------------------
@@ -2762,10 +2762,9 @@ static char* format_line(char *src, int li)
         int ofs = offset;
         char *dest = scr_out_buf; // [MAX_SCR_COLS + MAX_TABSTOP * 2]
 
-        memset(dest, ' ', MAX_SCR_COLS + MAX_TABSTOP * 2);
-
         c = '~'; // char in col 0 in non-existent lines is '~'
-        for (co = 0; co < columns + MAX_TABSTOP; co++) {
+        co = 0;
+        while (co < columns + tabstop) {
                 // have we gone past the end?
                 if (src < end) {
                         c = *src++;
@@ -2790,11 +2789,11 @@ static char* format_line(char *src, int li)
                                 }
                         }
                 }
-                dest[co] = c;
+                dest[co++] = c;
                 // discard scrolled-off-to-the-left portion,
                 // in tabstop-sized pieces
                 if (ofs >= tabstop && co >= tabstop) {
-                        memmove(dest, dest + tabstop, co + 1);
+                        memmove(dest, dest + tabstop, co);
                         co -= tabstop;
                         ofs -= tabstop;
                 }
@@ -2803,9 +2802,14 @@ static char* format_line(char *src, int li)
         }
         // check "short line, gigantic offset" case
         if (co < ofs)
-                ofs = co + 1;
-        dest[ofs + MAX_SCR_COLS] = '\0';
-        return &dest[ofs];
+                ofs = co;
+        // discard last scrolled off part
+        co -= ofs;
+        dest += ofs;
+        // fill the rest with spaces
+        if (co < columns)
+                memset(&dest[co], ' ', columns - co);
+        return dest;
 }
 
 //----- Refresh the changed screen lines -----------------------