svn commit: r347054 - head/lib/libvgl

[Bruce Evans]

Author: bde
Date: Fri May  3 13:06:46 2019
New Revision: 347054
URL: https://svnweb.freebsd.org/changeset/base/347054

Log:
  Fix copying planar bitmaps when the horizontal start and end are both not
  multiples of 8.  Then the misaligned pixels at the end were not copied.
  
  Clean up variable misuse related to this bug.  The width in bytes was
  first calculated correctly and used to do complicated reblocking
  correctly, but it was stored in an unrelated scratch variable and later
  recalculated with an off-by-1-error, so the last byte (times 4 planes)
  in the intermediate copy was not copied.
  
  This doubly-misaligned case is especially slow.  Misalignment complicates
  the reblocking, and each misaligment requires a read before write, and this
  read is still not done from the shadow buffer.

Modified:
  head/lib/libvgl/bitmap.c

Modified: head/lib/libvgl/bitmap.c
==============================================================================
--- head/lib/libvgl/bitmap.c	Fri May  3 09:38:23 2019	(r347053)
+++ head/lib/libvgl/bitmap.c	Fri May  3 13:06:46 2019	(r347054)
@@ -47,7 +47,7 @@ static int color2bit[16] = {0x00000000, 0x00000001, 0x
 static void
 WriteVerticalLine(VGLBitmap *dst, int x, int y, int width, byte *line)
 {
-  int i, pos, last, planepos, start_offset, end_offset, offset;
+  int bwidth, i, pos, last, planepos, start_offset, end_offset, offset;
   int len;
   unsigned int word = 0;
   byte *address;
@@ -58,13 +58,13 @@ WriteVerticalLine(VGLBitmap *dst, int x, int y, int wi
   case VIDBUF4S:
     start_offset = (x & 0x07);
     end_offset = (x + width) & 0x07;
-    i = (width + start_offset) / 8;
+    bwidth = (width + start_offset) / 8;
     if (end_offset)
-	i++;
+	bwidth++;
     VGLPlane[0] = VGLBuf;
-    VGLPlane[1] = VGLPlane[0] + i;
-    VGLPlane[2] = VGLPlane[1] + i;
-    VGLPlane[3] = VGLPlane[2] + i;
+    VGLPlane[1] = VGLPlane[0] + bwidth;
+    VGLPlane[2] = VGLPlane[1] + bwidth;
+    VGLPlane[3] = VGLPlane[2] + bwidth;
     pos = 0;
     planepos = 0;
     last = 8 - start_offset;
@@ -87,9 +87,6 @@ WriteVerticalLine(VGLBitmap *dst, int x, int y, int wi
       VGLPlane[2][planepos] = word>>16;
       VGLPlane[3][planepos] = word>>24;
     }
-    if (start_offset || end_offset)
-      width+=8;
-    width /= 8;
     outb(0x3ce, 0x01); outb(0x3cf, 0x00);		/* set/reset enable */
     outb(0x3ce, 0x08); outb(0x3cf, 0xff);		/* bit mask */
     for (i=0; i<4; i++) {
@@ -103,7 +100,7 @@ WriteVerticalLine(VGLBitmap *dst, int x, int y, int wi
 	  VGLPlane[i][planepos] |= dst->Bitmap[pos+planepos] & mask[end_offset];
 	if (start_offset)
 	  VGLPlane[i][0] |= dst->Bitmap[pos] & ~mask[start_offset];
-	bcopy(&VGLPlane[i][0], dst->Bitmap + pos, width);
+	bcopy(&VGLPlane[i][0], dst->Bitmap + pos, bwidth);
       } else {	/* VIDBUF4S */
 	if (end_offset) {
 	  offset = VGLSetSegment(pos + planepos);
@@ -112,9 +109,9 @@ WriteVerticalLine(VGLBitmap *dst, int x, int y, int wi
 	offset = VGLSetSegment(pos);
 	if (start_offset)
 	  VGLPlane[i][0] |= dst->Bitmap[offset] & ~mask[start_offset];
-	for (last = width; ; ) { 
+	for (last = bwidth; ; ) { 
 	  len = min(VGLAdpInfo.va_window_size - offset, last);
-	  bcopy(&VGLPlane[i][width - last], dst->Bitmap + offset, len);
+	  bcopy(&VGLPlane[i][bwidth - last], dst->Bitmap + offset, len);
 	  pos += len;
 	  last -= len;
 	  if (last <= 0)