Mercurial > repos > blastem
changeset 2002:fc8fd89aeba9
Fix VGM delay calculation overflow when a YM-2612 write follows a PSG write in close succession
author | Mike Pavone <pavone@retrodev.com> |
---|---|
date | Tue, 14 Jul 2020 20:19:47 -0700 |
parents | f77d36a975ff |
children | 4c418ee9a9d8 |
files | vgm.c |
diffstat | 1 files changed, 11 insertions(+), 0 deletions(-) [+] |
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--- a/vgm.c Sun Jul 12 23:09:02 2020 -0700 +++ b/vgm.c Tue Jul 14 20:19:47 2020 -0700 @@ -60,8 +60,15 @@ } } +#include "util.h" static void add_wait(vgm_writer *writer, uint32_t cycle) { + if (cycle < writer->last_cycle) { + //This can happen when a YM-2612 write happens immediately after a PSG write + //due to the relatively low granularity of the PSG's internal clock + //given that VGM only has a granularity of 44.1 kHz ignoring this is harmless + return; + } uint64_t last_sample = (uint64_t)writer->last_cycle * (uint64_t)44100; last_sample /= (uint64_t)writer->master_clock; uint64_t sample = (uint64_t)cycle * (uint64_t)44100; @@ -73,10 +80,12 @@ wait_commands(writer, delta); } +static uint8_t last_cmd; void vgm_sn76489_write(vgm_writer *writer, uint32_t cycle, uint8_t value) { add_wait(writer, cycle); uint8_t cmd[2] = {CMD_PSG, value}; + last_cmd = CMD_PSG; fwrite(cmd, 1, sizeof(cmd), writer->f); } @@ -89,6 +98,7 @@ { add_wait(writer, cycle); uint8_t cmd[3] = {CMD_YM2612_0, reg, value}; + last_cmd = CMD_YM2612_0; fwrite(cmd, 1, sizeof(cmd), writer->f); } @@ -96,6 +106,7 @@ { add_wait(writer, cycle); uint8_t cmd[3] = {CMD_YM2612_1, reg, value}; + last_cmd = CMD_YM2612_1; fwrite(cmd, 1, sizeof(cmd), writer->f); }