diff options
Diffstat (limited to 'ym2612.c')
| -rw-r--r-- | ym2612.c | 90 |
1 files changed, 65 insertions, 25 deletions
@@ -252,6 +252,39 @@ void ym_free(ym2612_context *context) #define TIMER_A_MAX 1023 #define TIMER_B_MAX 255 +#define CSM_MODE 0x80 + +static void keyon(ym_operator *op, ym_channel *channel) +{ + //Deal with "infinite" attack rates + uint8_t rate = op->rates[PHASE_ATTACK]; + if (rate) { + uint8_t ks = channel->keycode >> op->key_scaling;; + rate = rate*2 + ks; + } + if (rate >= 62) { + op->env_phase = PHASE_DECAY; + op->envelope = 0; + } else { + op->env_phase = PHASE_ATTACK; + } + op->phase_counter = 0; +} + +static const uint8_t keyon_bits[] = {0x10, 0x40, 0x20, 0x80}; + +static void csm_keyoff(ym2612_context *context) +{ + context->csm_keyon = 0; + uint8_t changes = 0xF0 ^ context->channels[2].keyon; + for (uint8_t op = 2*4, bit = 0; op < 3*4; op++, bit++) + { + if (changes & keyon_bits[bit]) { + context->operators[op].env_phase = PHASE_RELEASE; + } + } +} + void ym_run(ym2612_context * context, uint32_t to_cycle) { //printf("Running YM2612 from cycle %d to cycle %d\n", context->current_cycle, to_cycle); @@ -262,6 +295,9 @@ void ym_run(ym2612_context * context, uint32_t to_cycle) if (context->timer_control & BIT_TIMERA_ENABLE) { if (context->timer_a != TIMER_A_MAX) { context->timer_a++; + if (context->csm_keyon) { + csm_keyoff(context); + } } else { if (context->timer_control & BIT_TIMERA_LOAD) { context->timer_control &= ~BIT_TIMERA_LOAD; @@ -269,6 +305,16 @@ void ym_run(ym2612_context * context, uint32_t to_cycle) context->status |= BIT_STATUS_TIMERA; } context->timer_a = context->timer_a_load; + if (!context->csm_keyon && context->ch3_mode == CSM_MODE) { + context->csm_keyon = 0xF0; + uint8_t changes = 0xF0 ^ context->channels[2].keyon;; + for (uint8_t op = 2*4, bit = 0; op < 3*4; op++, bit++) + { + if (changes & keyon_bits[bit]) { + keyon(context->operators + op, context->channels + 2); + } + } + } } } if (!context->sub_timer_b) { @@ -309,22 +355,12 @@ void ym_run(ym2612_context * context, uint32_t to_cycle) //operator->envelope = operator->sustain_level; operator->env_phase = PHASE_SUSTAIN; } - for(;;) { - rate = operator->rates[operator->env_phase]; - if (rate) { - uint8_t ks = channel->keycode >> operator->key_scaling;; - rate = rate*2 + ks; - if (rate > 63) { - rate = 63; - } - } - //Deal with "infinite" rates - //According to Nemesis this should be handled in key-on instead - if (rate >= 62 && operator->env_phase == PHASE_ATTACK) { - operator->env_phase = PHASE_DECAY; - operator->envelope = 0; - } else { - break; + rate = operator->rates[operator->env_phase]; + if (rate) { + uint8_t ks = channel->keycode >> operator->key_scaling;; + rate = rate*2 + ks; + if (rate > 63) { + rate = 63; } } uint32_t cycle_shift = rate < 0x30 ? ((0x2F - rate) >> 2) : 0; @@ -727,6 +763,9 @@ void ym_data_write(ym2612_context * context, uint8_t value) if (value & BIT_TIMERB_RESET) { context->status &= ~BIT_STATUS_TIMERB; } + if (context->ch3_mode == CSM_MODE && (value & 0xC0) != CSM_MODE && context->csm_keyon) { + csm_keyoff(context); + } context->ch3_mode = value & 0xC0; break; } @@ -736,19 +775,20 @@ void ym_data_write(ym2612_context * context, uint8_t value) if (channel > 2) { channel--; } - uint8_t bits[] = {0x10, 0x40, 0x20, 0x80}; + uint8_t changes = channel == 2 + ? (value | context->csm_keyon) ^ (context->channels[channel].keyon | context->csm_keyon) + : value ^ context->channels[channel].keyon; + context->channels[channel].keyon = value & 0xF0; for (uint8_t op = channel * 4, bit = 0; op < (channel + 1) * 4; op++, bit++) { - if (value & bits[bit]) { - if (context->operators[op].env_phase == PHASE_RELEASE) - { + if (changes & keyon_bits[bit]) { + if (value & keyon_bits[bit]) { first_key_on = 1; //printf("Key On for operator %d in channel %d\n", op, channel); - context->operators[op].phase_counter = 0; - context->operators[op].env_phase = PHASE_ATTACK; + keyon(context->operators + op, context->channels + channel); + } else { + //printf("Key Off for operator %d in channel %d\n", op, channel); + context->operators[op].env_phase = PHASE_RELEASE; } - } else { - //printf("Key Off for operator %d in channel %d\n", op, channel); - context->operators[op].env_phase = PHASE_RELEASE; } } } |