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Merge pull request #3943 from 86Box/tc1995

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Restore correct CGA compatible mode behavior in (S)VGA.
This commit is contained in:
Miran Grča
2023-12-27 05:56:34 +01:00
committed by GitHub
parent 7678a86d6c f0f52279c4
commit acdc2c7aee
1 changed files with 8 additions and 9 deletions
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17
src/video/vid_svga.c
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@@ -618,7 +618,7 @@ svga_recalctimings(svga_t *svga)
svga->ma_latch = ((svga->crtc[0xc] << 8) | svga->crtc[0xd]) + ((svga->crtc[8] & 0x60) >> 5);
svga->ca_adj = 0;
svga->rowcount = svga->crtc[9] & 31;
svga->rowcount = svga->crtc[9] & 0x1f;
svga->hdisp_time = svga->hdisp;
svga->render = svga_render_blank;
@@ -639,27 +639,26 @@ svga_recalctimings(svga_t *svga)
svga->hdisp *= (svga->seqregs[1] & 8) ? 16 : 8;
svga->hdisp_old = svga->hdisp;
if ((svga->bpp <= 8) || ((svga->gdcreg[5] & 0x60) == 0x00)) {
if ((svga->bpp <= 8) || ((svga->gdcreg[5] & 0x60) <= 0x20)) {
if ((svga->gdcreg[5] & 0x60) == 0x00) {
if (svga->seqregs[1] & 8) /*Low res (320)*/
svga->render = svga_render_4bpp_lowres;
else
svga->render = svga_render_4bpp_highres;
} else if ((svga->gdcreg[5] & 0x60) == 0x20) {
if (svga->seqregs[1] & 8) /*Low res (320)*/
svga->render = svga_render_2bpp_lowres;
else
svga->render = svga_render_2bpp_highres;
} else {
svga->map8 = svga->pallook;
if (svga->attrregs[0x10] & 0x40) /*Low res (320)*/
if (svga->lowres) /*Low res (320)*/
svga->render = svga_render_8bpp_lowres;
else
svga->render = svga_render_8bpp_highres;
}
} else {
switch (svga->gdcreg[5] & 0x60) {
case 0x20: /*4 colours*/
if (svga->seqregs[1] & 8) /*Low res (320)*/
svga->render = svga_render_2bpp_lowres;
else
svga->render = svga_render_2bpp_highres;
break;
case 0x40:
case 0x60: /*256+ colours*/
switch (svga->bpp) {