On Sun, 31 Dec 2023, Paolo Bonzini wrote:
Do not go through the panning buffer unless the address wraps in the middle of the line.Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> --- hw/display/vga-helpers.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/hw/display/vga-helpers.h b/hw/display/vga-helpers.h index 29933562c45..60ddb27d946 100644 --- a/hw/display/vga-helpers.h +++ b/hw/display/vga-helpers.h @@ -265,6 +265,18 @@ static void *vga_draw_line8d2(VGACommonState *vga, uint8_t *d, palette = vga->last_palette; hpel = (hpel >> 1) & 3; + + /* For 256 color modes, we can adjust the source address and write directly + * to the destination, even if horizontal pel panning is active. However, + * the loop below assumes that the address does not wrap in the middle of a + * plane. If that happens... + */ + if (addr + (width >> 3) * 4 < VGA_VRAM_SIZE) { + addr += hpel * 4; + hpel = 0; + } + + /* ... use the panning buffer as in planar modes. */ if (hpel) { width += 8; d = vga->panning_buf;
Is it possible to do these checks once in vga.c and instead of changing the return value of the draw functions pass panning_buf as d if needed? Maybe that way the draw funcs could be left unchanged?
Regards, BALATON Zoltan
