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-rw-r--r--genesis.c9
-rw-r--r--ym2612.c49
-rw-r--r--ym2612.h5
3 files changed, 34 insertions, 29 deletions
diff --git a/genesis.c b/genesis.c
index ad21944..73a920d 100644
--- a/genesis.c
+++ b/genesis.c
@@ -403,11 +403,8 @@ m68k_context * sync_components(m68k_context * context, uint32_t address)
}
context->current_cycle -= deduction;
z80_adjust_cycles(z_context, deduction);
- gen->ym->current_cycle -= deduction;
+ ym_adjust_cycles(gen->ym, deduction);
gen->psg->cycles -= deduction;
- if (gen->ym->write_cycle != CYCLE_NEVER) {
- gen->ym->write_cycle = gen->ym->write_cycle >= deduction ? gen->ym->write_cycle - deduction : 0;
- }
if (gen->reset_cycle != CYCLE_NEVER) {
gen->reset_cycle -= deduction;
}
@@ -878,7 +875,7 @@ static uint8_t io_read(uint32_t location, m68k_context * context)
value = gen->zram[location & 0x1FFF];
} else if (location < 0x6000) {
sync_sound(gen, context->current_cycle);
- value = ym_read_status(gen->ym);
+ value = ym_read_status(gen->ym, context->current_cycle);
} else {
value = 0xFF;
}
@@ -991,7 +988,7 @@ static uint8_t z80_read_ym(uint32_t location, void * vcontext)
z80_context * context = vcontext;
genesis_context * gen = context->system;
sync_sound(gen, context->Z80_CYCLE);
- return ym_read_status(gen->ym);
+ return ym_read_status(gen->ym, context->Z80_CYCLE);
}
static uint8_t z80_read_bank(uint32_t location, void * vcontext)
diff --git a/ym2612.c b/ym2612.c
index 38416bf..d65e885 100644
--- a/ym2612.c
+++ b/ym2612.c
@@ -21,9 +21,7 @@
#define dfopen(var, fname, mode)
#endif
-#define BUSY_CYCLES_ADDRESS 17
-#define BUSY_CYCLES_DATA_LOW 83
-#define BUSY_CYCLES_DATA_HIGH 47
+#define BUSY_CYCLES 32
#define OP_UPDATE_PERIOD 144
#define BIT_TIMERA_ENABLE 0x1
@@ -122,6 +120,21 @@ void ym_adjust_master_clock(ym2612_context * context, uint32_t master_clock)
render_audio_adjust_clock(context->audio, master_clock, context->clock_inc * NUM_OPERATORS);
}
+void ym_adjust_cycles(ym2612_context *context, uint32_t deduction)
+{
+ context->current_cycle -= deduction;
+ if (context->write_cycle != CYCLE_NEVER && context->write_cycle >= deduction) {
+ context->write_cycle -= deduction;
+ } else {
+ context->write_cycle = CYCLE_NEVER;
+ }
+ if (context->busy_start != CYCLE_NEVER && context->busy_start >= deduction) {
+ context->busy_start -= deduction;
+ } else {
+ context->busy_start = CYCLE_NEVER;
+ }
+}
+
#ifdef __ANDROID__
#define log2(x) (log(x)/log(2))
#endif
@@ -173,6 +186,7 @@ void ym_init(ym2612_context * context, uint32_t master_clock, uint32_t clock_div
dfopen(debug_file, "ym_debug.txt", "w");
memset(context, 0, sizeof(*context));
context->clock_inc = clock_div * 6;
+ context->busy_cycles = BUSY_CYCLES * context->clock_inc;
context->audio = render_audio_source(master_clock, context->clock_inc * NUM_OPERATORS, 2);
//some games seem to expect that the LR flags start out as 1
@@ -635,10 +649,6 @@ void ym_run(ym2612_context * context, uint32_t to_cycle)
}
}
- if (context->current_cycle >= context->write_cycle + (context->busy_cycles * context->clock_inc / 6)) {
- context->status &= 0x7F;
- context->write_cycle = CYCLE_NEVER;
- }
//printf("Done running YM2612 at cycle %d\n", context->current_cycle, to_cycle);
}
@@ -647,9 +657,6 @@ void ym_address_write_part1(ym2612_context * context, uint8_t address)
//printf("address_write_part1: %X\n", address);
context->selected_reg = address;
context->selected_part = 0;
- context->write_cycle = context->current_cycle;
- context->busy_cycles = BUSY_CYCLES_ADDRESS;
- context->status |= 0x80;
}
void ym_address_write_part2(ym2612_context * context, uint8_t address)
@@ -657,9 +664,6 @@ void ym_address_write_part2(ym2612_context * context, uint8_t address)
//printf("address_write_part2: %X\n", address);
context->selected_reg = address;
context->selected_part = 1;
- context->write_cycle = context->current_cycle;
- context->busy_cycles = BUSY_CYCLES_ADDRESS;
- context->status |= 0x80;
}
static uint8_t fnum_to_keycode[] = {
@@ -768,6 +772,9 @@ static uint32_t ym_calc_phase_inc(ym2612_context * context, ym_operator * operat
void ym_data_write(ym2612_context * context, uint8_t value)
{
+ context->write_cycle = context->current_cycle;
+ context->busy_start = context->current_cycle + context->clock_inc;
+
if (context->selected_reg >= YM_REG_END) {
return;
}
@@ -1108,15 +1115,15 @@ void ym_data_write(ym2612_context * context, uint8_t value)
}
}
}
-
- context->write_cycle = context->current_cycle;
- context->busy_cycles = context->selected_reg < 0xA0 ? BUSY_CYCLES_DATA_LOW : BUSY_CYCLES_DATA_HIGH;
- context->status |= 0x80;
}
-uint8_t ym_read_status(ym2612_context * context)
+uint8_t ym_read_status(ym2612_context * context, uint32_t cycle)
{
- return context->status;
+ uint8_t status = context->status;
+ if (cycle >= context->busy_start && cycle < context->busy_start + context->busy_cycles) {
+ status |= 0x80;
+ }
+ return status;
}
void ym_print_channel_info(ym2612_context *context, int channel)
@@ -1228,7 +1235,7 @@ void ym_serialize(ym2612_context *context, serialize_buffer *buf)
save_int8(buf, context->selected_part);
save_int32(buf, context->current_cycle);
save_int32(buf, context->write_cycle);
- save_int32(buf, context->busy_cycles);
+ save_int32(buf, context->busy_start);
}
void ym_deserialize(deserialize_buffer *buf, void *vcontext)
@@ -1303,5 +1310,5 @@ void ym_deserialize(deserialize_buffer *buf, void *vcontext)
context->selected_part = load_int8(buf);
context->current_cycle = load_int32(buf);
context->write_cycle = load_int32(buf);
- context->busy_cycles = load_int32(buf);
+ context->busy_start = load_int32(buf);
}
diff --git a/ym2612.h b/ym2612.h
index 860e642..8694b3a 100644
--- a/ym2612.h
+++ b/ym2612.h
@@ -69,8 +69,8 @@ typedef struct {
audio_source *audio;
uint32_t clock_inc;
uint32_t current_cycle;
- //TODO: Condense the next two fields into one
uint32_t write_cycle;
+ uint32_t busy_start;
uint32_t busy_cycles;
int32_t volume_mult;
int32_t volume_div;
@@ -134,11 +134,12 @@ void ym_reset(ym2612_context *context);
void ym_free(ym2612_context *context);
void ym_enable_zero_offset(ym2612_context *context, uint8_t enabled);
void ym_adjust_master_clock(ym2612_context * context, uint32_t master_clock);
+void ym_adjust_cycles(ym2612_context *context, uint32_t deduction);
void ym_run(ym2612_context * context, uint32_t to_cycle);
void ym_address_write_part1(ym2612_context * context, uint8_t address);
void ym_address_write_part2(ym2612_context * context, uint8_t address);
void ym_data_write(ym2612_context * context, uint8_t value);
-uint8_t ym_read_status(ym2612_context * context);
+uint8_t ym_read_status(ym2612_context * context, uint32_t cycle);
uint8_t ym_load_gst(ym2612_context * context, FILE * gstfile);
uint8_t ym_save_gst(ym2612_context * context, FILE * gstfile);
void ym_print_channel_info(ym2612_context *context, int channel);
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-19 18:22:30 +0000