Mercurial > repos > blastem
changeset 2128:b0dcf5c9f353
Fix some issues with PCM dma/CPU write conflicts
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sun, 13 Mar 2022 11:36:06 -0700 |
| parents | 1bf30397dd45 |
| children | 4c9e447aa25b |
| files | rf5c164.c segacd.c |
| diffstat | 2 files changed, 13 insertions(+), 0 deletions(-) [+] |
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--- a/rf5c164.c Sat Mar 12 22:54:41 2022 -0800 +++ b/rf5c164.c Sun Mar 13 11:36:06 2022 -0700 @@ -147,6 +147,8 @@ CHECK; case 10: //refresh? + //does refresh happen at the same rate when sounding disabled? warning in sega docs suggests maybe not + write_if_not_sounding(pcm); CHECK; case 11: write_always(pcm);
--- a/segacd.c Sat Mar 12 22:54:41 2022 -0800 +++ b/segacd.c Sun Mar 13 11:36:06 2022 -0700 @@ -365,6 +365,12 @@ //need to run CD drive because there may be a PCM DMA underway cdd_run(cd, m68k->current_cycle); rf5c164_run(&cd->pcm, m68k->current_cycle); + while ((cd->pcm.flags & 0x81) == 1) { + //not sounding, but pending write + //DMA write conflict presumably adds wait states + m68k->current_cycle += 4; + rf5c164_run(&cd->pcm, m68k->current_cycle); + } rf5c164_write(&cd->pcm, address >> 1, value); } return vcontext; @@ -889,6 +895,11 @@ case DST_PCM_RAM: dma_addr &= (1 << 13) - 1; rf5c164_run(&cd->pcm, cd->cdc.cycle); + while ((cd->pcm.flags & 0x81) == 1) { + //not sounding, but pending write + //DMA write conflict with CPU + rf5c164_run(&cd->pcm, cd->pcm.cycle + 4); + } rf5c164_write(&cd->pcm, 0x1000 | (dma_addr >> 1), value); dma_addr += 2; cd->cdc_dst_low = dma_addr & 7;