From: kub Date: Sat, 8 Feb 2020 14:20:05 +0000 (+0100) Subject: vdp fifo: kludge for DMA fill interrupted by CPU X-Git-Tag: v2.00~789 X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=987f07974913f48ec019274ffb1f7ebca76cc8ff;p=picodrive.git vdp fifo: kludge for DMA fill interrupted by CPU --- diff --git a/pico/videoport.c b/pico/videoport.c index 881a74a3..0a6a103f 100644 --- a/pico/videoport.c +++ b/pico/videoport.c @@ -26,7 +26,7 @@ int (*PicoDmaHook)(unsigned int source, int len, unsigned short **base, unsigned * fifo_cnt: #slots remaining for active FIFO write (#writes<<#bytep) * fifo_total: #total FIFO entries pending * fifo_data: last values transferred through fifo - * fifo_queue: fifo transfer queue (#writes, VRAM_byte_p) + * fifo_queue: fifo transfer queue (#writes, flags) * * FIFO states: empty total=0 * inuse total>0 && total<4 @@ -95,42 +95,66 @@ const unsigned char vdpsl2cyc_40[] = { // slot # to 68k cycles/4 since HINT // last transferred FIFO data, ...x = index XXX currently only CPU static short fifo_data[4], fifo_dx; // queued FIFO transfers, ...x = index, ...l = queue length -// each entry has 2 values: [n]>>1=#writes, [n]&1=is VRAM byte access +// each entry has 2 values: [n]>>2=#writes, [n]&3=flags:2=DMA fill 1=byte access static int fifo_queue[8], fifo_qx, fifo_ql; signed int fifo_cnt; // pending slots for current queue entry unsigned short fifo_slot; // last executed slot in current scanline unsigned int fifo_total; // total# of pending FIFO entries -// sync FIFO to cycles -void PicoVideoFIFOSync(int cycles) +// do the FIFO math +static __inline int AdvanceFIFOEntry(int slots) +{ + int l = slots, b = fifo_queue[fifo_qx&7] & 1; + + if (l > fifo_cnt) + l = fifo_cnt; + fifo_total -= ((fifo_cnt & b) + l) >> b; + fifo_cnt -= l; + + if (fifo_cnt == 0) { + fifo_qx ++, fifo_ql --; + fifo_cnt= (fifo_queue[fifo_qx&7] >> 2) << (fifo_queue[fifo_qx&7] & 1); + } + return l; +} + +static __inline int GetFIFOSlot(struct PicoVideo *pv, int cycles) { - struct PicoVideo *pv = &Pico.video; int active = !(pv->status & SR_VB) && (pv->reg[1] & 0x40); int h40 = pv->reg[12] & 1; const unsigned char *cs = h40 ? vdpcyc2sl_40 : vdpcyc2sl_32; + + if (active) return cs[cycles/4]; + else return (cycles * vdpcyc2sl_bl[h40] + cycles) >> 16; +} + +static inline int GetFIFOCycles(struct PicoVideo *pv, int slot) +{ + int active = !(pv->status & SR_VB) && (pv->reg[1] & 0x40); + int h40 = pv->reg[12] & 1; + const unsigned char *sc = h40 ? vdpsl2cyc_40 : vdpsl2cyc_32; + + if (active) return sc[slot]*4; + else return ((slot * vdpsl2cyc_bl[h40] + slot) >> 16); +} + +// sync FIFO to cycles +void PicoVideoFIFOSync(int cycles) +{ + struct PicoVideo *pv = &Pico.video; int slots, done; // calculate #slots since last executed slot - if (active) slots = cs[cycles/4]; - else slots = (cycles * vdpcyc2sl_bl[h40] + cycles) >> 16; + slots = GetFIFOSlot(pv, cycles); slots -= fifo_slot; // advance FIFO queue by #done slots done = slots; while (done > 0 && fifo_ql) { - int l = done, b = fifo_queue[fifo_qx&7] & 1; - if (l > fifo_cnt) - l = fifo_cnt; - fifo_total -= ((fifo_cnt & b) + l) >> b; + int l = AdvanceFIFOEntry(done); fifo_slot += l; - fifo_cnt -= l; done -= l; - - if (fifo_cnt == 0) { - fifo_qx ++, fifo_ql --; - fifo_cnt= (fifo_queue[fifo_qx&7] >> 1) << (fifo_queue[fifo_qx&7] & 1); - } } // release CPU and terminate DMA if FIFO isn't blocking the 68k anymore @@ -150,7 +174,6 @@ int PicoVideoFIFODrain(int level, int cycles) struct PicoVideo *pv = &Pico.video; int active = !(pv->status & SR_VB) && (pv->reg[1] & 0x40); int h40 = pv->reg[12] & 1; - const unsigned char *sc = h40 ? vdpsl2cyc_40 : vdpsl2cyc_32; int maxsl = vdpslots[h40 + 2*active]; // max xfer slots in this scanline int burn = 0; @@ -169,19 +192,11 @@ int PicoVideoFIFODrain(int level, int cycles) } else { // advance FIFO to target slot and CPU to cycles at that slot fifo_slot = slot; - if (active) cycles = sc[slot]*4; - else cycles = ((slot * vdpsl2cyc_bl[h40] + slot) >> 16); + cycles = GetFIFOCycles(pv, slot); } burn += cycles - ocyc; - slot -= last; - fifo_total -= ((fifo_cnt & b) + slot) >> b; - fifo_cnt -= slot; - - if (fifo_cnt == 0) { - fifo_qx ++, fifo_ql --; - fifo_cnt= (fifo_queue[fifo_qx&7] >> 1) << (fifo_queue[fifo_qx&7] & 1); - } + AdvanceFIFOEntry(slot - last); } // release CPU and terminate DMA if FIFO isn't blocking the bus anymore @@ -201,10 +216,6 @@ int PicoVideoFIFODrain(int level, int cycles) int PicoVideoFIFORead(void) { struct PicoVideo *pv = &Pico.video; - int active = !(pv->status & SR_VB) && (pv->reg[1] & 0x40); - int h40 = pv->reg[12] & 1; - const unsigned char *cs = h40 ? vdpcyc2sl_40 : vdpcyc2sl_32; - const unsigned char *sc = h40 ? vdpsl2cyc_40 : vdpsl2cyc_32; int lc = SekCyclesDone()-Pico.t.m68c_line_start+4; int burn = 0; @@ -217,43 +228,33 @@ int PicoVideoFIFORead(void) pv->status |= PVS_CPURD; // target slot is in later scanline else { // use next VDP access slot for reading, block 68k until then - if (active) { - fifo_slot = cs[lc/4] + 1; - burn += sc[fifo_slot]*4; - } else { - fifo_slot = ((lc * vdpcyc2sl_bl[h40] + lc) >> 16) + 1; - burn += ((fifo_slot * vdpsl2cyc_bl[h40] + fifo_slot) >> 16); - } - burn -= lc; + fifo_slot = GetFIFOSlot(pv, lc) + 1; + burn += GetFIFOCycles(pv, fifo_slot) - lc; } return burn; } // write VDP data port -int PicoVideoFIFOWrite(int count, int byte_p, unsigned sr_mask,unsigned sr_flags) +int PicoVideoFIFOWrite(int count, int flags, unsigned sr_mask,unsigned sr_flags) { struct PicoVideo *pv = &Pico.video; - int active = !(pv->status & SR_VB) && (pv->reg[1] & 0x40); - int h40 = pv->reg[12] & 1; - const unsigned char *cs = h40 ? vdpcyc2sl_40 : vdpcyc2sl_32; int lc = SekCyclesDone()-Pico.t.m68c_line_start+4; int burn = 0; PicoVideoFIFOSync(lc); pv->status = (pv->status & ~sr_mask) | sr_flags; - if (count) { + if (count && fifo_ql < 8) { // update FIFO state if it was empty if (fifo_total == 0 && count) { - if (active) fifo_slot = cs[lc/4]; - else fifo_slot = (lc * vdpcyc2sl_bl[h40] + lc) >> 16; - fifo_cnt = count << byte_p; + fifo_slot = GetFIFOSlot(pv, lc); + fifo_cnt = count << (flags&1); } // create xfer queue entry int x = (fifo_qx + fifo_ql) & 7; - fifo_queue[x] = (count << 1) | byte_p; + fifo_queue[x] = (count << 2) | flags; fifo_ql ++; fifo_total += count; } @@ -261,6 +262,11 @@ int PicoVideoFIFOWrite(int count, int byte_p, unsigned sr_mask,unsigned sr_flags // if CPU is waiting for the bus, advance CPU and FIFO until bus is free if ((pv->status & (PVS_CPUWR|PVS_DMAFILL)) == PVS_CPUWR) burn = PicoVideoFIFODrain(4, lc); + else if (fifo_queue[fifo_qx&7]&2) { + // if interrupting a DMA fill terminate it + AdvanceFIFOEntry(fifo_cnt); + pv->status &= ~PVS_DMAFILL; + } return burn; } @@ -515,7 +521,7 @@ static void DmaCopy(int len) int source; elprintf(EL_VDPDMA, "DmaCopy len %i [%u]", len, SekCyclesDone()); - SekCyclesBurnRun(PicoVideoFIFOWrite(len, 1, PVS_CPUWR|PVS_DMAPEND, SR_DMA)); + SekCyclesBurnRun(PicoVideoFIFOWrite(len, 1, PVS_CPUWR | PVS_DMAPEND, SR_DMA)); source =Pico.video.reg[0x15]; source|=Pico.video.reg[0x16]<<8; @@ -544,7 +550,8 @@ static NOINLINE void DmaFill(int data) len = GetDmaLength(); elprintf(EL_VDPDMA, "DmaFill len %i inc %i [%u]", len, inc, SekCyclesDone()); - SekCyclesBurnRun(PicoVideoFIFOWrite(len, Pico.video.type == 1, PVS_CPUWR|PVS_DMAPEND, SR_DMA)); + SekCyclesBurnRun(PicoVideoFIFOWrite(len, 2|(Pico.video.type == 1), + PVS_CPUWR | PVS_DMAPEND, SR_DMA)); switch (Pico.video.type) {