diff options
| -rw-r--r-- | blastem.c | 28 |
1 files changed, 25 insertions, 3 deletions
@@ -366,7 +366,12 @@ m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_ while(v_context->flags & FLAG_DMA_RUN) { vdp_run_dma_done(v_context, gen->frame_end); if (v_context->cycles >= gen->frame_end) { - context->current_cycle = v_context->cycles; + uint32_t cycle_diff = v_context->cycles - context->current_cycle; + uint32_t m68k_cycle_diff = (cycle_diff / MCLKS_PER_68K) * MCLKS_PER_68K; + if (m68k_cycle_diff < cycle_diff) { + m68k_cycle_diff += MCLKS_PER_68K; + } + context->current_cycle += m68k_cycle_diff; gen->bus_busy = 1; sync_components(context, 0); gen->bus_busy = 0; @@ -381,12 +386,24 @@ m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_ while(v_context->flags & FLAG_DMA_RUN) { vdp_run_dma_done(v_context, gen->frame_end); if (v_context->cycles >= gen->frame_end) { - context->current_cycle = v_context->cycles; + uint32_t cycle_diff = v_context->cycles - context->current_cycle; + uint32_t m68k_cycle_diff = (cycle_diff / MCLKS_PER_68K) * MCLKS_PER_68K; + if (m68k_cycle_diff < cycle_diff) { + m68k_cycle_diff += MCLKS_PER_68K; + } + context->current_cycle += m68k_cycle_diff; gen->bus_busy = 1; sync_components(context, 0); gen->bus_busy = 0; } + if (!(v_context->flags & FLAG_DMA_RUN)) { + //two more slots of delay are needed to kill sufficient sprite capacity in Overdrive + //TODO: Measure exact value with logic analyzer + vdp_run_context(v_context, v_context->cycles + 1); + vdp_run_context(v_context, v_context->cycles + 1); + } } + if (blocked < 0) { blocked = vdp_control_port_write(v_context, value); } else { @@ -403,7 +420,12 @@ m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_ } if (v_context->cycles != before_cycle) { //printf("68K paused for %d (%d) cycles at cycle %d (%d) for write\n", v_context->cycles - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle); - context->current_cycle = v_context->cycles; + uint32_t cycle_diff = v_context->cycles - context->current_cycle; + uint32_t m68k_cycle_diff = (cycle_diff / MCLKS_PER_68K) * MCLKS_PER_68K; + if (m68k_cycle_diff < cycle_diff) { + m68k_cycle_diff += MCLKS_PER_68K; + } + context->current_cycle += m68k_cycle_diff; #ifdef REFRESH_EMULATION last_sync_cycle = context->current_cycle; #endif |