Mercurial > repos > blastem
diff ym2612.c @ 483:3e1573fa22cf
Implement turbo/slow motion feature that overclocks or underclocks the entire system at the push of a button
| author | Mike Pavone <pavone@retrodev.com> |
|---|---|
| date | Tue, 01 Oct 2013 23:51:16 -0700 |
| parents | 140af5509ce7 |
| children | b7b7a1cab44a |
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--- a/ym2612.c Wed Sep 18 19:10:54 2013 -0700 +++ b/ym2612.c Tue Oct 01 23:51:16 2013 -0700 @@ -1,6 +1,6 @@ /* Copyright 2013 Michael Pavone - This file is part of BlastEm. + This file is part of BlastEm. BlastEm is free software distributed under the terms of the GNU General Public License version 3 or greater. See COPYING for full license text. */ #include <string.h> @@ -127,6 +127,13 @@ } } } +#define BUFFER_INC_RES 1000000000UL + +void ym_adjust_master_clock(ym2612_context * context, uint32_t master_clock) +{ + uint64_t old_inc = context->buffer_inc; + context->buffer_inc = ((BUFFER_INC_RES * (uint64_t)context->sample_rate) / (uint64_t)master_clock) * (uint64_t)context->clock_inc; +} void ym_init(ym2612_context * context, uint32_t sample_rate, uint32_t master_clock, uint32_t clock_div, uint32_t sample_limit, uint32_t options) { @@ -134,8 +141,10 @@ memset(context, 0, sizeof(*context)); context->audio_buffer = malloc(sizeof(*context->audio_buffer) * sample_limit*2); context->back_buffer = malloc(sizeof(*context->audio_buffer) * sample_limit*2); - context->buffer_inc = ((double)sample_rate / (double)master_clock) * clock_div * 6; + context->sample_rate = sample_rate; context->clock_inc = clock_div * 6; + ym_adjust_master_clock(context, master_clock); + context->sample_limit = sample_limit*2; context->write_cycle = CYCLE_NEVER; for (int i = 0; i < NUM_OPERATORS; i++) { @@ -451,29 +460,29 @@ context->buffer_fraction += context->buffer_inc; if (context->current_op == NUM_OPERATORS) { context->current_op = 0; - if (context->buffer_fraction > 1.0) { - context->buffer_fraction -= 1.0; - context->audio_buffer[context->buffer_pos] = 0; - context->audio_buffer[context->buffer_pos + 1] = 0; - for (int i = 0; i < NUM_CHANNELS; i++) { - int16_t value = context->channels[i].output & 0x3FE0; - if (value & 0x2000) { - value |= 0xC000; - } - if (context->channels[i].logfile) { - fwrite(&value, sizeof(value), 1, context->channels[i].logfile); - } - if (context->channels[i].lr & 0x80) { - context->audio_buffer[context->buffer_pos] += value / YM_VOLUME_DIVIDER; - } - if (context->channels[i].lr & 0x40) { - context->audio_buffer[context->buffer_pos+1] += value / YM_VOLUME_DIVIDER; - } + } + if (context->buffer_fraction > BUFFER_INC_RES) { + context->buffer_fraction -= BUFFER_INC_RES; + context->audio_buffer[context->buffer_pos] = 0; + context->audio_buffer[context->buffer_pos + 1] = 0; + for (int i = 0; i < NUM_CHANNELS; i++) { + int16_t value = context->channels[i].output & 0x3FE0; + if (value & 0x2000) { + value |= 0xC000; } - context->buffer_pos += 2; - if (context->buffer_pos == context->sample_limit) { - render_wait_ym(context); + if (context->channels[i].logfile) { + fwrite(&value, sizeof(value), 1, context->channels[i].logfile); + } + if (context->channels[i].lr & 0x80) { + context->audio_buffer[context->buffer_pos] += value / YM_VOLUME_DIVIDER; } + if (context->channels[i].lr & 0x40) { + context->audio_buffer[context->buffer_pos+1] += value / YM_VOLUME_DIVIDER; + } + } + context->buffer_pos += 2; + if (context->buffer_pos == context->sample_limit) { + render_wait_ym(context); } } }