diff options
| author | Mike Pavone <pavone@retrodev.com> | 2013-05-19 13:47:47 -0700 |
|---|---|---|
| committer | Mike Pavone <pavone@retrodev.com> | 2013-05-19 13:47:47 -0700 |
| commit | e04f6e836f9a1a5e8a249b2f9b9717752668f262 (patch) | |
| tree | 520d4cb4b7fb7639850925ebb654304075e54167 | |
| parent | 653a7fbec86098bded803d4a5b255a7c6e39239a (diff) | |
Don't sync the 68K clock to the VDP clock unless the 68K had to wait for the VDP. This unfortunately breaks the direct color DMA demos, but should be more correct overall.
| -rw-r--r-- | blastem.c | 6 |
1 files changed, 4 insertions, 2 deletions
@@ -253,8 +253,8 @@ m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_ vdp_context * v_context = context->video_context; if (vdp_port < 0x10) { int blocked; + uint32_t before_cycle = v_context->cycles; if (vdp_port < 4) { - uint32_t before_cycle = v_context->cycles; while (vdp_data_port_write(v_context, value) < 0) { while(v_context->flags & FLAG_DMA_RUN) { vdp_run_dma_done(v_context, mclks_per_frame); @@ -314,7 +314,9 @@ m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_ printf("Illegal write to HV Counter port %X\n", vdp_port); exit(1); } - context->current_cycle = v_context->cycles/MCLKS_PER_68K; + if (v_context->cycles != before_cycle) { + context->current_cycle = v_context->cycles / MCLKS_PER_68K; + } } else if (vdp_port < 0x18) { //TODO: Implement PSG } else { |