Mercurial > repos > blastem
changeset 1364:30123ca5856c
Added some code to try and prevent Z80 accesses and refresh cycles from screwing up interrupt latency more than on hardware
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Fri, 19 May 2017 20:54:04 -0700 |
| parents | df6af7187b36 |
| children | 6dd2c3edd0b5 |
| files | genesis.c genesis.h |
| diffstat | 2 files changed, 17 insertions(+), 0 deletions(-) [+] |
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--- a/genesis.c Fri May 19 20:27:35 2017 -0700 +++ b/genesis.c Fri May 19 20:54:04 2017 -0700 @@ -96,6 +96,19 @@ //This can cause issues with the implementation of STOP though context->target_cycle = context->current_cycle; } + if (context->target_cycle == context->int_cycle) { + //Currently delays from Z80 access and refresh are applied only when we sync + //this can cause extra latency when it comes to interrupts + //to prevent this code forces some extra synchronization in the period immediately before an interrupt + if ((context->target_cycle - context->current_cycle) > gen->int_latency_prev1) { + context->target_cycle = context->sync_cycle = context->int_cycle - gen->int_latency_prev1; + } else if ((context->target_cycle - context->current_cycle) > gen->int_latency_prev2) { + context->target_cycle = context->sync_cycle = context->int_cycle - gen->int_latency_prev2; + } else { + context->target_cycle = context->sync_cycle = context->current_cycle; + } + + } /*printf("Cyc: %d, Trgt: %d, Int Cyc: %d, Int: %d, Mask: %X, V: %d, H: %d, HICount: %d, HReg: %d, Line: %d\n", context->current_cycle, context->target_cycle, context->int_cycle, context->int_num, (context->status & 0x7), v_context->regs[REG_MODE_2] & 0x20, v_context->regs[REG_MODE_1] & 0x10, v_context->hint_counter, v_context->regs[REG_HINT], v_context->cycles / MCLKS_LINE);*/ @@ -1003,6 +1016,8 @@ gen->frame_end = vdp_cycles_to_frame_end(gen->vdp); char * config_cycles = tern_find_path(config, "clocks\0max_cycles\0", TVAL_PTR).ptrval; gen->max_cycles = config_cycles ? atoi(config_cycles) : DEFAULT_SYNC_INTERVAL; + gen->int_latency_prev1 = MCLKS_PER_68K * 32; + gen->int_latency_prev2 = MCLKS_PER_68K * 16; char * lowpass_cutoff_str = tern_find_path(config, "audio\0lowpass_cutoff\0", TVAL_PTR).ptrval; uint32_t lowpass_cutoff = lowpass_cutoff_str ? atoi(lowpass_cutoff_str) : DEFAULT_LOWPASS_CUTOFF;
--- a/genesis.h Fri May 19 20:27:35 2017 -0700 +++ b/genesis.h Fri May 19 20:54:04 2017 -0700 @@ -40,6 +40,8 @@ uint32_t normal_clock; //Normal master clock (used to restore master clock after turbo mode) uint32_t frame_end; uint32_t max_cycles; + uint32_t int_latency_prev1; + uint32_t int_latency_prev2; uint8_t bank_regs[8]; uint16_t mapper_start_index; uint8_t save_type;