ati-vga: Implement scissor rectangle clipping for 2D operations
Use scissor registers to clip blit operations. This is required for text rendering in X using the r128 driver. Without it overly-wide glyphs are drawn and create all sorts of chaos. The visible destination rectangle (vis_dst) is the intersection of the scissor rectangle and the destination rectangle (dst). The src also needs to be offset if clipped on the top and/or left sides to ensure that src data is read correctly and appears clipped when drawn rather than shifted. Signed-off-by: Chad Jablonski <chad@jablonski.xyz> Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu> [balaton: Fix build without pixman] Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu> Message-ID: <4752dfbe240102c2ffa1f2cdab4c9442d4f0dcfb.1773020351.git.balaton@eik.bme.hu> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Chad Jablonski committed
Mar 9, 2026 at 02:47 UTC
527b07d2c59f2cda5186476b9d8b79371102689b
1 file changed
+58
-29
hw/display/ati_2d.c
+58
-29
@@ -52,6 +52,7 @@ typedef struct {
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uint32_t frgd_clr;
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const uint8_t *palette;
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const uint8_t *vram_end;
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+ QemuRect scissor;
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QemuRect dst;
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int dst_stride;
@@ -91,6 +92,11 @@ static void setup_2d_blt_ctx(const ATIVGAState *s, ATI2DCtx *ctx)
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ctx->dst_offset = s->regs.dst_offset;
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ctx->vram_end = s->vga.vram_ptr + s->vga.vram_size;
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+ ctx->scissor.width = s->regs.sc_right - s->regs.sc_left + 1;
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+ ctx->scissor.height = s->regs.sc_bottom - s->regs.sc_top + 1;
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+ ctx->scissor.x = s->regs.sc_left;
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+ ctx->scissor.y = s->regs.sc_top;
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+
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ctx->dst.width = s->regs.dst_width;
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ctx->dst.height = s->regs.dst_height;
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ctx->dst.x = (ctx->left_to_right ?
@@ -125,6 +131,8 @@ static void setup_2d_blt_ctx(const ATIVGAState *s, ATI2DCtx *ctx)
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static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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{
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+ QemuRect vis_src, vis_dst;
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+
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if (!ctx->bpp) {
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qemu_log_mask(LOG_GUEST_ERROR, "Invalid bpp\n");
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return false;
@@ -139,6 +147,29 @@ static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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qemu_log_mask(LOG_UNIMP, "blt outside vram not implemented\n");
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return false;
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}
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+ qemu_rect_intersect(&ctx->dst, &ctx->scissor, &vis_dst);
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+ if (!vis_dst.height || !vis_dst.width) {
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+ /* Nothing is visible, completely clipped */
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+ return false;
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+ }
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+ /*
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+ * The src must be offset if clipping is applied to the dst.
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+ * This is so that when the source is blit to a dst clipped
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+ * on the top or left the src image is not shifted into the
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+ * clipped region but actually clipped.
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+ */
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+ vis_src.x = ctx->src.x + (vis_dst.x - ctx->dst.x);
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+ vis_src.y = ctx->src.y + (vis_dst.y - ctx->dst.y);
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+ vis_src.width = vis_dst.width;
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+ vis_src.height = vis_dst.height;
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+
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+ DPRINTF("dst: (%d,%d) %dx%d -> vis_dst: (%d,%d) %dx%d\n",
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+ ctx->dst.x, ctx->dst.y, ctx->dst.width, ctx->dst.height,
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+ vis_dst.x, vis_dst.y, vis_dst.width, vis_dst.height);
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+ DPRINTF("src: (%d,%d) %dx%d -> vis_src: (%d,%d) %dx%d\n",
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+ ctx->src.x, ctx->src.y, ctx->dst.width, ctx->dst.height,
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+ vis_src.x, vis_src.y, vis_src.width, vis_src.height);
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+
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switch (ctx->rop3) {
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case ROP3_SRCCOPY:
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{
@@ -147,10 +178,9 @@ static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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qemu_log_mask(LOG_GUEST_ERROR, "Zero source pitch\n");
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return false;
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}
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- if (ctx->src.x > 0x3fff || ctx->src.y > 0x3fff ||
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- ctx->src_bits >= ctx->vram_end ||
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- ctx->src_bits + ctx->src.x + (ctx->src.y + ctx->dst.height) *
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- ctx->src_stride >= ctx->vram_end) {
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+ if (vis_src.x > 0x3fff || vis_src.y > 0x3fff ||
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+ ctx->src_bits >= ctx->vram_end || ctx->src_bits + vis_src.x +
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+ (vis_src.y + vis_dst.height) * ctx->src_stride >= ctx->vram_end) {
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qemu_log_mask(LOG_UNIMP, "blt outside vram not implemented\n");
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return false;
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}
@@ -159,8 +189,8 @@ static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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ctx->src_bits, ctx->dst_bits,
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ctx->src_stride / sizeof(uint32_t),
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ctx->dst_stride / sizeof(uint32_t),
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- ctx->bpp, ctx->bpp, ctx->src.x, ctx->src.y, ctx->dst.x,
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- ctx->dst.y, ctx->dst.width, ctx->dst.height);
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+ ctx->bpp, ctx->bpp, vis_src.x, vis_src.y, vis_dst.x, vis_dst.y,
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+ vis_dst.width, vis_dst.height);
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#ifdef CONFIG_PIXMAN
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int src_stride_words = ctx->src_stride / sizeof(uint32_t);
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int dst_stride_words = ctx->dst_stride / sizeof(uint32_t);
@@ -169,24 +199,24 @@ static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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fallback = !pixman_blt((uint32_t *)ctx->src_bits,
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(uint32_t *)ctx->dst_bits, src_stride_words,
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dst_stride_words, ctx->bpp, ctx->bpp,
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- ctx->src.x, ctx->src.y, ctx->dst.x,
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- ctx->dst.y, ctx->dst.width, ctx->dst.height);
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+ vis_src.x, vis_src.y, vis_dst.x, vis_dst.y,
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+ vis_dst.width, vis_dst.height);
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} else if (use_pixman & BIT(1)) {
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/* FIXME: We only really need a temporary if src and dst overlap */
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- int llb = ctx->dst.width * (ctx->bpp / 8);
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+ int llb = vis_dst.width * (ctx->bpp / 8);
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int tmp_stride_words = DIV_ROUND_UP(llb, sizeof(uint32_t));
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uint32_t *tmp = g_malloc(tmp_stride_words * sizeof(uint32_t) *
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- ctx->dst.height);
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+ vis_dst.height);
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fallback = !pixman_blt((uint32_t *)ctx->src_bits, tmp,
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src_stride_words, tmp_stride_words, ctx->bpp,
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- ctx->bpp, ctx->src.x, ctx->src.y, 0, 0,
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- ctx->dst.width, ctx->dst.height);
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+ ctx->bpp, vis_src.x, vis_src.y, 0, 0,
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+ vis_dst.width, vis_dst.height);
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if (!fallback) {
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fallback = !pixman_blt(tmp, (uint32_t *)ctx->dst_bits,
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tmp_stride_words, dst_stride_words,
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ctx->bpp, ctx->bpp, 0, 0,
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- ctx->dst.x, ctx->dst.y,
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- ctx->dst.width, ctx->dst.height);
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+ vis_dst.x, vis_dst.y,
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+ vis_dst.width, vis_dst.height);
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}
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g_free(tmp);
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} else
@@ -196,20 +226,20 @@ static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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}
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if (fallback) {
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unsigned int y, i, j, bypp = ctx->bpp / 8;
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- for (y = 0; y < ctx->dst.height; y++) {
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- i = ctx->dst.x * bypp;
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- j = ctx->src.x * bypp;
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+ for (y = 0; y < vis_dst.height; y++) {
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+ i = vis_dst.x * bypp;
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+ j = vis_src.x * bypp;
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if (ctx->top_to_bottom) {
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- i += (ctx->dst.y + y) * ctx->dst_stride;
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- j += (ctx->src.y + y) * ctx->src_stride;
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+ i += (vis_dst.y + y) * ctx->dst_stride;
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+ j += (vis_src.y + y) * ctx->src_stride;
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} else {
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- i += (ctx->dst.y + ctx->dst.height - 1 - y)
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+ i += (vis_dst.y + vis_dst.height - 1 - y)
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* ctx->dst_stride;
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- j += (ctx->src.y + ctx->dst.height - 1 - y)
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+ j += (vis_src.y + vis_dst.height - 1 - y)
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* ctx->src_stride;
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}
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memmove(&ctx->dst_bits[i], &ctx->src_bits[j],
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- ctx->dst.width * bypp);
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+ vis_dst.width * bypp);
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}
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}
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break;
@@ -238,21 +268,20 @@ static bool ati_2d_do_blt(ATI2DCtx *ctx, uint8_t use_pixman)
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DPRINTF("pixman_fill(%p, %ld, %d, %d, %d, %d, %d, %x)\n",
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ctx->dst_bits, ctx->dst_stride / sizeof(uint32_t), ctx->bpp,
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- ctx->dst.x, ctx->dst.y, ctx->dst.width, ctx->dst.height,
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- filler);
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+ vis_dst.x, vis_dst.y, vis_dst.width, vis_dst.height, filler);
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#ifdef CONFIG_PIXMAN
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if (!(use_pixman & BIT(0)) ||
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!pixman_fill((uint32_t *)ctx->dst_bits,
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ctx->dst_stride / sizeof(uint32_t), ctx->bpp,
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- ctx->dst.x, ctx->dst.y,
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- ctx->dst.width, ctx->dst.height, filler))
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+ vis_dst.x, vis_dst.y, vis_dst.width, vis_dst.height,
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+ filler))
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#endif
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{
280
/* fallback when pixman failed or we don't want to call it */
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unsigned int x, y, i, bypp = ctx->bpp / 8;
253
- for (y = 0; y < ctx->dst.height; y++) {
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- i = ctx->dst.x * bypp + (ctx->dst.y + y) * ctx->dst_stride;
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- for (x = 0; x < ctx->dst.width; x++, i += bypp) {
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+ for (y = 0; y < vis_dst.height; y++) {
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+ i = vis_dst.x * bypp + (vis_dst.y + y) * ctx->dst_stride;
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+ for (x = 0; x < vis_dst.width; x++, i += bypp) {
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stn_he_p(&ctx->dst_bits[i], bypp, filler);
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}
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}