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Genesis-Plus-GX/source/sound/sound.c

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/***************************************************************************************
* Genesis Plus
* Sound Hardware
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
* Copyright (C) 2007-2011 Eke-Eke (Genesis Plus GX)
*
* Redistribution and use of this code or any derivative works are permitted
* provided that the following conditions are met:
*
* - Redistributions may not be sold, nor may they be used in a commercial
* product or activity.
*
* - Redistributions that are modified from the original source must include the
* complete source code, including the source code for all components used by a
* binary built from the modified sources. However, as a special exception, the
* source code distributed need not include anything that is normally distributed
* (in either source or binary form) with the major components (compiler, kernel,
* and so on) of the operating system on which the executable runs, unless that
* component itself accompanies the executable.
*
* - Redistributions must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************************/
#include "shared.h"
#include "Fir_Resampler.h"
/* Cycle-accurate samples */
static unsigned int psg_cycles_ratio;
static unsigned int psg_cycles_count;
static unsigned int fm_cycles_ratio;
static unsigned int fm_cycles_count;
/* YM chip function pointers */
static void (*YM_Reset)(void);
static void (*YM_Update)(int *buffer, int length);
static void (*YM_Write)(unsigned int a, unsigned int v);
/* Run FM chip for required M-cycles */
static inline void fm_update(unsigned int cycles)
{
if (cycles > fm_cycles_count)
{
/* period to run */
cycles -= fm_cycles_count;
/* update cycle count */
fm_cycles_count += cycles;
/* number of samples during period */
unsigned int cnt = cycles / fm_cycles_ratio;
/* remaining cycles */
unsigned int remain = cycles % fm_cycles_ratio;
if (remain)
{
/* one sample ahead */
fm_cycles_count += fm_cycles_ratio - remain;
cnt++;
}
/* select input sample buffer */
int32 *buffer = Fir_Resampler_buffer();
if (buffer)
{
Fir_Resampler_write(cnt << 1);
}
else
{
buffer = snd.fm.pos;
snd.fm.pos += (cnt << 1);
}
/* run FM chip & get samples */
YM_Update(buffer, cnt);
}
}
/* Run PSG chip for required M-cycles */
static inline void psg_update(unsigned int cycles)
{
if (cycles > psg_cycles_count)
{
/* period to run */
cycles -= psg_cycles_count;
/* update cycle count */
psg_cycles_count += cycles;
/* number of samples during period */
unsigned int cnt = cycles / psg_cycles_ratio;
/* remaining cycles */
unsigned int remain = cycles % psg_cycles_ratio;
if (remain)
{
/* one sample ahead */
psg_cycles_count += psg_cycles_ratio - remain;
cnt++;
}
/* run PSG chip & get samples */
SN76489_Update(snd.psg.pos, cnt);
snd.psg.pos += cnt;
}
}
/* Initialize sound chips emulation */
void sound_init(void)
{
/* Number of M-cycles executed per second. */
/* */
/* The original Genesis would run exactly 53693175 M-cycles (53203424 for PAL), with */
/* 3420 M-cycles per line and 262 (313 for PAL) lines per frame, which gives an exact */
/* framerate of 59.92 (49.70 for PAL) fps. */
/* */
/* On some systems, the output framerate is not exactly 60 or 50 fps because we need */
/* 100% smooth video and therefore frame emulation is synchronized with VSYNC, which */
/* period is never exactly 1/60 or 1/50 seconds. */
/* */
/* For optimal sound rendering, input samplerate (number of samples rendered per frame) */
/* is the exact output samplerate (number of samples played per second) divided by the */
/* exact output framerate (number of frames emulated per seconds). */
/* */
/* This ensure there is no audio skipping or lag between emulated frames, while keeping */
/* accurate timings for sound chips execution & synchronization. */
/* */
double mclk = MCYCLES_PER_LINE * lines_per_frame * snd.frame_rate;
/* For better accuracy, sound chips run in synchronization with 68k and Z80 cpus */
/* These values give the exact number of M-cycles between 2 rendered samples. */
/* we use 21.11 fixed point precision (max. mcycle value is 3420*313 i.e 21 bits max) */
psg_cycles_ratio = (unsigned int)(mclk / (double) snd.sample_rate * 2048.0);
fm_cycles_ratio = psg_cycles_ratio;
fm_cycles_count = 0;
psg_cycles_count = 0;
/* Initialize core emulation (input clock based on input frequency for 100% accuracy) */
/* By default, both chips are running at the output frequency. */
SN76489_Init(mclk/15.0,snd.sample_rate);
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
/* YM2612 */
YM2612Init(mclk/7.0,snd.sample_rate);
YM_Reset = YM2612ResetChip;
YM_Update = YM2612Update;
YM_Write = YM2612Write;
/* In HQ mode, YM2612 is running at its original rate (one sample each 144*7 M-cycles) */
/* FM stream is resampled to the output frequency at the end of a frame. */
if (config.hq_fm)
{
fm_cycles_ratio = 144 * 7 * (1 << 11);
Fir_Resampler_time_ratio(mclk / (double)snd.sample_rate / (144.0 * 7.0), config.rolloff);
}
}
else
{
/* YM2413 */
YM2413Init(mclk/15.0,snd.sample_rate);
YM_Reset = YM2413ResetChip;
YM_Update = YM2413Update;
YM_Write = YM2413Write;
/* In HQ mode, YM2413 is running at its original rate (one sample each 72*15 M-cycles) */
/* FM stream is resampled to the output frequency at the end of a frame. */
if (config.hq_fm)
{
fm_cycles_ratio = 72 * 15 * (1 << 11);
Fir_Resampler_time_ratio(mclk / (double)snd.sample_rate / (72.0 * 15.0), config.rolloff);
}
}
#ifdef LOGSOUND
error("%d mcycles per PSG samples\n", psg_cycles_ratio);
error("%d mcycles per FM samples\n", fm_cycles_ratio);
#endif
}
/* Reset sound chips emulation */
void sound_reset(void)
{
YM_Reset();
SN76489_Reset();
fm_cycles_count = 0;
psg_cycles_count = 0;
}
void sound_restore()
{
int size;
uint8 *ptr, *temp;
/* save YM context */
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
size = YM2612GetContextSize();
ptr = YM2612GetContextPtr();
}
else
{
size = YM2413GetContextSize();
ptr = YM2413GetContextPtr();
}
temp = malloc(size);
if (temp)
{
memcpy(temp, ptr, size);
}
/* reinitialize sound chips */
sound_init();
/* restore YM context */
if (temp)
{
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
YM2612Restore(temp);
}
else
{
YM2413Restore(temp);
}
free(temp);
}
}
int sound_context_save(uint8 *state)
{
int bufferptr = 0;
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
bufferptr = YM2612SaveContext(state);
}
else
{
save_param(YM2413GetContextPtr(),YM2413GetContextSize());
}
save_param(SN76489_GetContextPtr(),SN76489_GetContextSize());
save_param(&fm_cycles_count,sizeof(fm_cycles_count));
save_param(&psg_cycles_count,sizeof(psg_cycles_count));
return bufferptr;
}
int sound_context_load(uint8 *state, char *version)
{
int bufferptr = 0;
if (((system_hw & SYSTEM_PBC) == SYSTEM_MD) || ((version[13] == 0x35) && (version[15] == 0x30)))
{
bufferptr = YM2612LoadContext(state);
}
else
{
load_param(YM2413GetContextPtr(),YM2413GetContextSize());
}
load_param(SN76489_GetContextPtr(),SN76489_GetContextSize());
load_param(&fm_cycles_count,sizeof(fm_cycles_count));
load_param(&psg_cycles_count,sizeof(psg_cycles_count));
fm_cycles_count = psg_cycles_count;
return bufferptr;
}
/* End of frame update, return the number of samples run so far. */
int sound_update(unsigned int cycles)
{
/* run PSG & FM chips until end of frame */
cycles <<= 11;
psg_update(cycles);
fm_update(cycles);
int size = snd.psg.pos - snd.psg.buffer;
#ifdef LOGSOUND
error("%d PSG samples available\n",size);
#endif
/* FM resampling */
if (config.hq_fm)
{
/* get available FM samples */
int avail = Fir_Resampler_avail();
/* resynchronize FM & PSG chips */
if (avail < size)
{
/* FM chip is late for one (or two) samples */
do
{
YM_Update(Fir_Resampler_buffer(), 1);
Fir_Resampler_write(2);
avail = Fir_Resampler_avail();
}
while (avail < size);
}
else
{
/* FM chip is ahead */
fm_cycles_count += (avail - size) * psg_cycles_ratio;
}
}
#ifdef LOGSOUND
if (config.hq_fm)
error("%d FM samples (%d) available\n",Fir_Resampler_avail(), Fir_Resampler_written() >> 1);
else
error("%d FM samples available\n",(snd.fm.pos - snd.fm.buffer)>>1);
#endif
#ifdef LOGSOUND
error("%lu PSG cycles run\n",psg_cycles_count);
error("%lu FM cycles run \n",fm_cycles_count);
#endif
/* adjust PSG & FM cycle counts for next frame */
psg_cycles_count -= cycles;
fm_cycles_count -= cycles;
#ifdef LOGSOUND
error("%lu PSG cycles left\n",psg_cycles_count);
error("%lu FM cycles left\n",fm_cycles_count);
#endif
return size;
}
/* Reset FM chip */
void fm_reset(unsigned int cycles)
{
fm_update(cycles << 11);
YM_Reset();
}
/* Write FM chip */
void fm_write(unsigned int cycles, unsigned int address, unsigned int data)
{
if (address & 1) fm_update(cycles << 11);
YM_Write(address, data);
}
/* Read FM status (YM2612 only) */
unsigned int fm_read(unsigned int cycles, unsigned int address)
{
fm_update(cycles << 11);
return YM2612Read();
}
/* Write PSG chip */
void psg_write(unsigned int cycles, unsigned int data)
{
psg_update(cycles << 11);
SN76489_Write(data);
}
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