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vid_ega: Extend 4bpp renderer to handle CGA 2bpp chunky graphics; Remove 2bpp renderer

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This also lets planes 2 and 3 be used.
This commit is contained in:
Ben Russell
2023-03-23 15:28:25 +13:00
parent 212e494328
commit 69c18755a4
3 changed files with 30 additions and 106 deletions
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27
src/video/vid_ega.c
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@@ -57,7 +57,7 @@ static uint8_t ega_rotate[8][256];
static uint32_t pallook16[256], pallook64[256];
static int ega_type = 0, old_overscan_color = 0;
extern uint8_t edatlookup[4][4];
uint8_t egaremap2bpp[256];
/* 3C2 controls default mode on EGA. On VGA, it determines monitor type (mono or colour):
7=CGA mode (200 lines), 9=EGA mode (350 lines), 8=EGA mode (200 lines). */
@@ -419,19 +419,8 @@ ega_recalctimings(ega_t *ega)
ega->hdisp_old = ega->hdisp;
} else {
ega->hdisp *= (ega->seqregs[1] & 8) ? 16 : 8;
ega->render = ega_render_graphics;
ega->hdisp_old = ega->hdisp;
switch (ega->gdcreg[5] & 0x20) {
case 0x00:
ega->render = ega_render_4bpp;
break;
case 0x20:
if (ega->seqregs[1] & 8)
ega->render = ega_render_2bpp_lowres;
else
ega->render = ega_render_2bpp_highres;
break;
}
}
}
@@ -1060,6 +1049,18 @@ ega_init(ega_t *ega, int monitor_type, int is_mono)
}
}
for (c = 0; c < 256; c++) {
egaremap2bpp[c] = 0;
if (c & 0x01)
egaremap2bpp[c] |= 0x01;
if (c & 0x04)
egaremap2bpp[c] |= 0x02;
if (c & 0x10)
egaremap2bpp[c] |= 0x04;
if (c & 0x40)
egaremap2bpp[c] |= 0x08;
}
if (is_mono) {
for (c = 0; c < 256; c++) {
if (((c >> 3) & 3) == 0)

103
src/video/vid_ega_render.c
View File

@@ -247,95 +247,7 @@ ega_render_text_80(ega_t *ega)
}
void
ega_render_2bpp_lowres(ega_t *ega)
{
int x;
uint8_t dat[2];
uint32_t addr, *p;
if ((ega->displine + ega->y_add) < 0)
return;
p = &buffer32->line[ega->displine + ega->y_add][ega->x_add];
if (ega->firstline_draw == 2000)
ega->firstline_draw = ega->displine;
ega->lastline_draw = ega->displine;
for (x = 0; x <= (ega->hdisp + ega->scrollcache); x += 16) {
addr = ega->remap_func(ega, ega->ma);
dat[0] = ega->vram[addr];
dat[1] = ega->vram[addr | 0x1];
if (ega->seqregs[1] & 4)
ega->ma += 2;
else
ega->ma += 4;
ega->ma &= ega->vrammask;
if (ega->crtc[0x17] & 0x80) {
p[0] = p[1] = ega->pallook[ega->egapal[(dat[0] >> 6) & 3]];
p[2] = p[3] = ega->pallook[ega->egapal[(dat[0] >> 4) & 3]];
p[4] = p[5] = ega->pallook[ega->egapal[(dat[0] >> 2) & 3]];
p[6] = p[7] = ega->pallook[ega->egapal[dat[0] & 3]];
p[8] = p[9] = ega->pallook[ega->egapal[(dat[1] >> 6) & 3]];
p[10] = p[11] = ega->pallook[ega->egapal[(dat[1] >> 4) & 3]];
p[12] = p[13] = ega->pallook[ega->egapal[(dat[1] >> 2) & 3]];
p[14] = p[15] = ega->pallook[ega->egapal[dat[1] & 3]];
} else
memset(p, 0x00, 16 * sizeof(uint32_t));
p += 16;
}
}
void
ega_render_2bpp_highres(ega_t *ega)
{
int x;
uint8_t dat[2];
uint32_t addr, *p;
if ((ega->displine + ega->y_add) < 0)
return;
p = &buffer32->line[ega->displine + ega->y_add][ega->x_add];
if (ega->firstline_draw == 2000)
ega->firstline_draw = ega->displine;
ega->lastline_draw = ega->displine;
for (x = 0; x <= (ega->hdisp + ega->scrollcache); x += 8) {
addr = ega->remap_func(ega, ega->ma);
dat[0] = ega->vram[addr];
dat[1] = ega->vram[addr | 0x1];
if (ega->seqregs[1] & 4)
ega->ma += 2;
else
ega->ma += 4;
ega->ma &= ega->vrammask;
if (ega->crtc[0x17] & 0x80) {
p[0] = ega->pallook[ega->egapal[(dat[0] >> 6) & 3]];
p[1] = ega->pallook[ega->egapal[(dat[0] >> 4) & 3]];
p[2] = ega->pallook[ega->egapal[(dat[0] >> 2) & 3]];
p[3] = ega->pallook[ega->egapal[dat[0] & 3]];
p[4] = ega->pallook[ega->egapal[(dat[1] >> 6) & 3]];
p[5] = ega->pallook[ega->egapal[(dat[1] >> 4) & 3]];
p[6] = ega->pallook[ega->egapal[(dat[1] >> 2) & 3]];
p[7] = ega->pallook[ega->egapal[dat[1] & 3]];
} else
memset(p, 0x00, 8 * sizeof(uint32_t));
p += 8;
}
}
void
ega_render_4bpp(ega_t *ega)
ega_render_graphics(ega_t *ega)
{
if ((ega->displine + ega->y_add) < 0)
return;
@@ -347,6 +259,7 @@ ega_render_4bpp(ega_t *ega)
ega->lastline_draw = ega->displine;
const bool doublewidth = ((ega->seqregs[1] & 8) != 0);
const bool cga2bpp = ((ega->gdcreg[5] & 0x20) != 0);
const int dotwidth = (doublewidth ? 2 : 1);
const int charwidth = dotwidth*8;
int secondcclk = 0;
@@ -369,6 +282,18 @@ ega_render_4bpp(ega_t *ega)
}
ega->ma &= 0x3ffff;
if (cga2bpp) {
// Remap CGA 2bpp-chunky data into fully planar data
uint8_t dat0 = egaremap2bpp[edat[1] ] | (egaremap2bpp[edat[0] ] << 4);
uint8_t dat1 = egaremap2bpp[edat[1]>>1] | (egaremap2bpp[edat[0]>>1] << 4);
uint8_t dat2 = egaremap2bpp[edat[3] ] | (egaremap2bpp[edat[2] ] << 4);
uint8_t dat3 = egaremap2bpp[edat[3]>>1] | (egaremap2bpp[edat[2]>>1] << 4);
edat[0] = dat0;
edat[1] = dat1;
edat[2] = dat2;
edat[3] = dat3;
}
if (ega->crtc[0x17] & 0x80) {
for (int i = 0; i < 4; i++) {
const int outoffs = i*(dotwidth<<1);