Introduce BlitterOr operation (backported from b23d3a3)

include/blitter.h

@@ -128,6 +128,17 @@ void BitmapCopyMasked(const BitmapT *dst, u_short x, u_short y,
 void BitmapCopyArea(const BitmapT *dst, u_short dx, u_short dy, 
                     const BitmapT *src, const Area2D *area);
 
+/* Blitter or operation. */
+/* TODO: does not behave correctly for unaligned `x` */
+void BlitterOrSetup(const BitmapT *dst, u_short x, u_short y,
+                      const BitmapT *src);
+void BlitterOrStart(short dstbpl, short srcbpl);
+
+#define BlitterOr(dst, dstbpl, x, y, src, srcbpl) ({  \
+  BlitterOrSetup((dst), (x), (y), (src));             \
+  BlitterOrStart((dstbpl), (srcbpl));                 \
+})
+
 /* Blitter fill. */
 void BlitterFillArea(const BitmapT *bitmap, short plane, const Area2D *area);
 

lib/libblit/BitmapOr.c

@@ -0,0 +1,9 @@
+#include <blitter.h>
+
+void BitmapOr(const BitmapT *dst, u_short x, u_short y, const BitmapT *src) {
+  short i, n = min(dst->depth, src->depth);
+
+  BlitterOrSetup(dst, x, y, src);
+  for (i = 0; i < n; i++)
+    BlitterOrStart(i, i);
+}

lib/libblit/BlitterOr.c

@@ -0,0 +1,52 @@
+#include <blitter.h>
+
+typedef struct {
+  const BitmapT *src;
+  const BitmapT *dst;
+  u_int start;
+  u_short size;
+} StateT;
+
+static StateT state[1];
+
+/* Supports any (x, y) and any source bitmap width. */
+void BlitterOrSetup(const BitmapT *dst, u_short x, u_short y,
+                    const BitmapT *src)
+{
+  /* Calculate real blit width. It can be greater than src->bytesPerRow! */
+  u_short width = (x & 15) + src->width;
+  u_short bytesPerRow = ((width + 15) & ~15) >> 3;
+  u_short srcmod = src->bytesPerRow - bytesPerRow;
+  u_short dstmod = dst->bytesPerRow - bytesPerRow;
+  u_short bltafwm = FirstWordMask[x & 15];
+  u_short bltalwm = LastWordMask[width & 15];
+  u_short bltshift = rorw(x & 15, 4);
+
+  state->src = src;
+  state->dst = dst;
+  state->start = ((x & ~15) >> 3) + y * dst->bytesPerRow;
+  state->size = (src->height << 6) | (bytesPerRow >> 1);
+
+  WaitBlitter();
+
+  custom->bltcon0 = A_OR_B | (SRCA | SRCB | DEST) | bltshift;
+  custom->bltcon1 = 0;
+  custom->bltafwm = bltafwm;
+  custom->bltalwm = bltalwm;
+  custom->bltamod = srcmod;
+  custom->bltbmod = dstmod;
+  custom->bltdmod = dstmod;
+}
+
+void BlitterOrStart(short dstbpl, short srcbpl) {
+  void *srcbpt = state->src->planes[srcbpl];
+  void *dstbpt = state->dst->planes[dstbpl] + state->start;
+  u_short bltsize = state->size;
+
+  WaitBlitter();
+
+  custom->bltapt = srcbpt;
+  custom->bltbpt = dstbpt;
+  custom->bltdpt = dstbpt;
+  custom->bltsize = bltsize;
+}

lib/libblit/Makefile

@@ -9,15 +9,17 @@ SOURCES := \
 	BitmapDecSaturated.c \
 	BitmapIncSaturated.c \
 	BitmapMakeMask.c \
+	BitmapOr.c \
 	BitmapSetArea.c \
 	BlitterCopy.c \
 	BlitterCopyArea.c \
 	BlitterCopyFast.c \
 	BlitterCopyMasked.c \
 	BlitterFillArea.c \
+	BlitterOr.c \
 	BlitterLine.c \
 	BlitterSetArea.c \
 	BlitterSetMaskArea.c \
-	WordMask.c \
+	WordMask.c
 
 include $(TOPDIR)/build/lib.mk