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core, handle background color DMA (aka fantom bitmap)

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kub 2024-01-13 12:07:13 +01:00
parent 68e06234e3
commit 724db457da
4 changed files with 97 additions and 1 deletions
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10
pico/videoport.c
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@ -522,6 +522,7 @@ static void DmaSlow(int len, u32 source)
u32 a = Pico.video.addr | (Pico.video.addr_u << 16), e;
u16 *r, *base = NULL;
u32 mask = 0x1ffff;
int lc = SekCyclesDone()-Pico.t.m68c_line_start;
elprintf(EL_VDPDMA, "DmaSlow[%i] %06x->%04x len %i inc=%i blank %i [%u] @ %06x",
Pico.video.type, source, a, len, inc, (Pico.video.status&SR_VB)||!(Pico.video.reg[1]&0x40),
@ -603,6 +604,15 @@ static void DmaSlow(int len, u32 source)
case 3: // cram
Pico.m.dirtyPal = 1;
r = PicoMem.cram;
if (inc == 0 && (Pico.video.reg[7] & 0x3f) == ((a/2) & 0x3f)) { // bg color DMA
PicoVideoSync(1);
int sl = VdpFIFO.fifo_hcounts[lc/clkdiv];
if (sl > VdpFIFO.fifo_hcounts[0]-5) // hint delay is 5 slots
sl = (s8)sl;
// TODO this is needed to cover timing inaccuracies
if (sl <= 12) sl = -2;
PicoDrawBgcDMA(base, source, mask, len, sl);
}
for (; len; len--)
{
r[(a / 2) & 0x3f] = base[source++ & mask] & 0xeee;