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comparison blastem.c @ 508:b976c6d6e5fb

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Initial attempt at emulating extended bank area access delays when 68K bus is busy with VDP stuff. Also emulate the extra delay on the second access of a word-wide read to the bank area. Needs work as it seems to break stuff.
author Michael Pavone <pavone@retrodev.com>
date Mon, 03 Feb 2014 09:18:10 -0800
parents b7b7a1cab44a
children a277de8c1a18
comparison
equal deleted inserted replaced
507:cc6030bd04c6 508:b976c6d6e5fb
310 } 310 }
311 vdp_port &= 0x1F; 311 vdp_port &= 0x1F;
312 //printf("vdp_port write: %X, value: %X, cycle: %d\n", vdp_port, value, context->current_cycle); 312 //printf("vdp_port write: %X, value: %X, cycle: %d\n", vdp_port, value, context->current_cycle);
313 sync_components(context, 0); 313 sync_components(context, 0);
314 vdp_context * v_context = context->video_context; 314 vdp_context * v_context = context->video_context;
315 genesis_context * gen = context->system;
315 if (vdp_port < 0x10) { 316 if (vdp_port < 0x10) {
316 int blocked; 317 int blocked;
317 uint32_t before_cycle = v_context->cycles; 318 uint32_t before_cycle = v_context->cycles;
318 if (vdp_port < 4) { 319 if (vdp_port < 4) {
320 gen->bus_busy = 1;
319 while (vdp_data_port_write(v_context, value) < 0) { 321 while (vdp_data_port_write(v_context, value) < 0) {
320 while(v_context->flags & FLAG_DMA_RUN) { 322 while(v_context->flags & FLAG_DMA_RUN) {
321 vdp_run_dma_done(v_context, mclks_per_frame); 323 vdp_run_dma_done(v_context, mclks_per_frame);
322 if (v_context->cycles >= mclks_per_frame) { 324 if (v_context->cycles >= mclks_per_frame) {
323 if (!headless) { 325 if (!headless) {
345 } 347 }
346 } 348 }
347 //context->current_cycle = v_context->cycles / MCLKS_PER_68K; 349 //context->current_cycle = v_context->cycles / MCLKS_PER_68K;
348 } 350 }
349 } else if(vdp_port < 8) { 351 } else if(vdp_port < 8) {
352 gen->bus_busy = 1;
350 blocked = vdp_control_port_write(v_context, value); 353 blocked = vdp_control_port_write(v_context, value);
351 if (blocked) { 354 if (blocked) {
352 while (blocked) { 355 while (blocked) {
353 while(v_context->flags & FLAG_DMA_RUN) { 356 while(v_context->flags & FLAG_DMA_RUN) {
354 vdp_run_dma_done(v_context, mclks_per_frame); 357 vdp_run_dma_done(v_context, mclks_per_frame);
392 if (v_context->cycles != before_cycle) { 395 if (v_context->cycles != before_cycle) {
393 //printf("68K paused for %d (%d) cycles at cycle %d (%d) for write\n", v_context->cycles / MCLKS_PER_68K - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle); 396 //printf("68K paused for %d (%d) cycles at cycle %d (%d) for write\n", v_context->cycles / MCLKS_PER_68K - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
394 context->current_cycle = v_context->cycles / MCLKS_PER_68K; 397 context->current_cycle = v_context->cycles / MCLKS_PER_68K;
395 } 398 }
396 } else if (vdp_port < 0x18) { 399 } else if (vdp_port < 0x18) {
397 genesis_context * gen = context->system;
398 sync_sound(gen, context->current_cycle * MCLKS_PER_68K); 400 sync_sound(gen, context->current_cycle * MCLKS_PER_68K);
399 psg_write(gen->psg, value); 401 psg_write(gen->psg, value);
400 } else { 402 } else {
401 //TODO: Implement undocumented test register(s) 403 //TODO: Implement undocumented test register(s)
404 }
405 if (gen->bus_busy)
406 {
407 //Lock the Z80 out of the bus until the VDP access is complete
408 sync_z80(gen->z80, v_context->cycles);
409 gen->bus_busy = 0;
402 } 410 }
403 return context; 411 return context;
404 } 412 }
405 413
406 m68k_context * vdp_port_write_b(uint32_t vdp_port, m68k_context * context, uint8_t value) 414 m68k_context * vdp_port_write_b(uint32_t vdp_port, m68k_context * context, uint8_t value)