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core vdp, optimize fifo writes

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This commit is contained in:
kub 2022-02-19 21:23:54 +00:00
parent 7ce6a6d18e
commit 4f6d3b2847
1 changed files with 24 additions and 35 deletions
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45
pico/videoport.c
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@ -237,7 +237,7 @@ static void SetFIFOState(struct VdpFIFO *vf, struct PicoVideo *pv)
}
}
if (vf->fifo_ql == 0) {
st &= ~(PVS_CPURD|PVS_FIFORUN);
st &= ~PVS_CPURD;
// terminate DMA if applicable
if (!(st & PVS_DMAFILL)) {
st &= ~(SR_DMA|PVS_DMABG);
@ -345,47 +345,36 @@ int PicoVideoFIFOWrite(int count, int flags, unsigned sr_mask,unsigned sr_flags)
int burn = 0, x;
// sync only needed if queue is too full or background dma might be deferred
if (vf->fifo_ql >= 6 || (pv->status & SR_DMA))
if ((vf->fifo_ql >= 6) | (pv->status & SR_DMA))
PicoVideoFIFOSync(lc);
pv->status = (pv->status & ~sr_mask) | sr_flags;
if (count && vf->fifo_ql < 7) {
// determine queue position for entry
x = (vf->fifo_qx + vf->fifo_ql - 1) & 7;
if (unlikely(vf->fifo_queue[x] & FQ_BGDMA)) {
// CPU FIFO writes have priority over a background DMA Fill/Copy
vf->fifo_queue[(x+1) & 7] = vf->fifo_queue[x]; // push bg DMA back
x = (x-1) & 7;
if (vf->fifo_ql == 1) {
// XXX if interrupting a DMA fill, fill data changes
pv->status &= ~PVS_FIFORUN;
}
}
if (unlikely(vf->fifo_queue[x] & FQ_BGDMA))
x = (x-1) & 7; // ignore bg dma ent (pushed back below if new ent created)
// determine queue position for entry
if (!(flags & FQ_BGDMA))
vf->fifo_total += count;
if (!vf->fifo_ql)
vf->fifo_slot = Cyc2Sl(vf, lc+7); // FIFO latency ~3 vdp slots
count <<= (flags & FQ_BYTE);
if ((pv->status & PVS_FIFORUN) && (vf->fifo_queue[x] & 7) == flags) {
// amalgamate entries if of same type
vf->fifo_queue[x] += (count << 3);
count <<= (flags & FQ_BYTE)+3;
if (vf->fifo_queue[x] && (vf->fifo_queue[x] & 7) == flags) {
// amalgamate entries if of same type and not empty (in case of bgdma)
vf->fifo_queue[x] += count;
} else {
// create new xfer queue entry
vf->fifo_ql ++;
x = (x+1) & 7;
vf->fifo_queue[x] = (count << 3) | flags;
}
// update FIFO state if it was empty
if (!(pv->status & PVS_FIFORUN))
vf->fifo_slot = Cyc2Sl(vf, lc+7); // FIFO latency ~3 vdp slots
pv->status |= PVS_FIFORUN;
vf->fifo_queue[(x+1)&7] = vf->fifo_queue[x]; // push back bg dma if exists
vf->fifo_queue[x] = count | flags;
}
// if CPU is waiting for the bus, advance CPU and FIFO until bus is free
// do this only if it would exhaust the available slots since last sync
x = (Cyc2Sl(vf,lc) - vf->fifo_slot) / 2; // lower bound of FIFO ents
if (vf->fifo_total > 4 + x && (pv->status & PVS_CPUWR))
if ((pv->status & PVS_CPUWR) && vf->fifo_total > 4 + x)
burn = PicoVideoFIFODrain(4, lc, 0);
return burn;
@ -763,7 +752,7 @@ static NOINLINE void CommandDma(void)
elprintf(EL_VDPDMA, "Dma overlap, left=%d @ %06x",
VdpFIFO.fifo_total, SekPc);
VdpFIFO.fifo_total = VdpFIFO.fifo_ql = 0;
pvid->status &= ~(PVS_FIFORUN|PVS_DMAFILL);
pvid->status &= ~PVS_DMAFILL;
}
len = GetDmaLength();
@ -1157,7 +1146,7 @@ void PicoVideoLoad(void)
vf->fifo_ql = vf->fifo_qx = vf->fifo_total = 0;
if (pv->fifo_cnt) {
int wc = pv->fifo_cnt;
pv->status |= PVS_FIFORUN|PVS_CPUWR;
pv->status |= PVS_CPUWR;
vf->fifo_total = (wc+b) >> b;
vf->fifo_queue[vf->fifo_qx + vf->fifo_ql] = (wc << 3) | b | FQ_FGDMA;
vf->fifo_ql ++;
@ -1165,7 +1154,7 @@ void PicoVideoLoad(void)
if (pv->fifo_bgcnt) {
int wc = pv->fifo_bgcnt;
if (!vf->fifo_ql)
pv->status |= PVS_FIFORUN|PVS_DMABG;
pv->status |= PVS_DMABG;
vf->fifo_queue[vf->fifo_qx + vf->fifo_ql] = (wc << 3) | FQ_BGDMA;
vf->fifo_ql ++;
}