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Implemented odd/even memory mode for EGA and VGA.

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This commit is contained in:
TomW 2015-08-12 20:37:39 +01:00
commit 12232fd7b8
5 changed files with 91 additions and 53 deletions
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21
src/vid_svga.c
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@ -162,6 +162,7 @@ void svga_out(uint16_t addr, uint8_t val, void *p)
case 5: svga->writemode=val&3; svga->readmode=val&8; break;
case 6:
// pclog("svga_out recalcmapping %p\n", svga);
svga->chain2 = val & 2;
if ((svga->gdcreg[6] & 0xc) != (val & 0xc))
{
// pclog("Write mapping %02X\n", val);
@ -740,6 +741,14 @@ void svga_write(uint32_t addr, uint8_t val, void *p)
writemask2=1<<(addr&3);
addr&=~3;
}
else if (svga->chain2)
{
writemask2 &= ~0xa;
if (addr & 1)
writemask2 <<= 1;
addr &= ~1;
addr <<= 2;
}
else
{
addr<<=2;
@ -900,6 +909,7 @@ uint8_t svga_read(uint32_t addr, void *p)
{
svga_t *svga = (svga_t *)p;
uint8_t temp, temp2, temp3, temp4;
int readplane = svga->readplane;
cycles -= video_timing_b;
cycles_lost += video_timing_b;
@ -918,7 +928,14 @@ uint8_t svga_read(uint32_t addr, void *p)
return 0xff;
return svga->vram[addr];
}
else addr<<=2;
else if (svga->chain2)
{
readplane = (readplane & 2) | (addr & 1);
addr &= ~1;
addr <<= 2;
}
else
addr<<=2;
addr &= 0x7fffff;
@ -946,7 +963,7 @@ uint8_t svga_read(uint32_t addr, void *p)
return ~(temp | temp2 | temp3 | temp4);
}
//pclog("Read %02X %04X %04X\n",vram[addr|svga->readplane],addr,svga->readplane);
return svga->vram[addr | svga->readplane];
return svga->vram[addr | readplane];
}
void svga_write_linear(uint32_t addr, uint8_t val, void *p)