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vid_ega: Fix address decoding for Odd/Even modes for the 4bpp gfx renderers

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This, combined with the Odd/Even fixes from a previous commit, gets the 64KB 640x350 2bpp modes working correctly.
Relevant issue: #2944
This commit is contained in:
Ben Russell
2023-03-20 20:07:39 +00:00
parent 77ba033fd9
commit 2a395efbc9
3 changed files with 78 additions and 22 deletions
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6
src/video/vid_ega_render.c
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@@ -352,6 +352,7 @@ ega_render_4bpp_lowres(ega_t *ega)
secondcclk = 0;
for (x = 0; x <= (ega->hdisp + ega->scrollcache); x += 16) {
addr = ega->remap_func(ega, ega->ma);
addr &= ega->vrammask;
if (ega->seqregs[1] & 4) {
// FIXME: Verify the behaviour of planes 1,3 on actual hardware
@@ -366,7 +367,7 @@ ega_render_4bpp_lowres(ega_t *ega)
*(uint32_t *) (&edat[0]) = *(uint32_t *) (&ega->vram[addr]);
ega->ma += 4;
}
ega->ma &= ega->vrammask;
ega->ma &= 0x3ffff;
if (ega->crtc[0x17] & 0x80) {
dat = edatlookup[edat[0] >> 6][edat[1] >> 6] | (edatlookup[edat[2] >> 6][edat[3] >> 6] << 2);
@@ -407,6 +408,7 @@ ega_render_4bpp_highres(ega_t *ega)
secondcclk = 0;
for (x = 0; x <= (ega->hdisp + ega->scrollcache); x += 8) {
addr = ega->remap_func(ega, ega->ma);
addr &= ega->vrammask;
if (ega->seqregs[1] & 4) {
// FIXME: Verify the behaviour of planes 1,3 on actual hardware
edat[0] = ega->vram[(addr | 0) ^ secondcclk];
@@ -420,7 +422,7 @@ ega_render_4bpp_highres(ega_t *ega)
*(uint32_t *) (&edat[0]) = *(uint32_t *) (&ega->vram[addr]);
ega->ma += 4;
}
ega->ma &= ega->vrammask;
ega->ma &= 0x3ffff;
if (ega->crtc[0x17] & 0x80) {
dat = edatlookup[edat[0] >> 6][edat[1] >> 6] | (edatlookup[edat[2] >> 6][edat[3] >> 6] << 2);