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

272 lines
7.3 KiB
C

/***************************************************************************************
* Genesis Plus
* Sound Hardware
*
* Copyright (C) 1998-2003 Charles Mac Donald (original code)
* Copyright (C) 2007-2016 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 "blip_buf.h"
/* FM output buffer (large enough to hold a whole frame at original chips rate) */
static int fm_buffer[1080 * 2];
static int fm_last[2];
static int *fm_ptr;
/* Cycle-accurate FM samples */
static uint32 fm_cycles_ratio;
static uint32 fm_cycles_start;
static uint32 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 until required M-cycles */
INLINE void fm_update(unsigned int cycles)
{
if (cycles > fm_cycles_count)
{
/* number of samples to run */
unsigned int samples = (cycles - fm_cycles_count + fm_cycles_ratio - 1) / fm_cycles_ratio;
/* run FM chip to sample buffer */
YM_Update(fm_ptr, samples);
/* update FM buffer pointer */
fm_ptr += (samples << 1);
/* update FM cycle counter */
fm_cycles_count += samples * fm_cycles_ratio;
}
}
void sound_init( void )
{
/* Initialize FM chip */
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
/* YM2612 */
YM2612Init();
YM2612Config(config.dac_bits);
YM_Reset = YM2612ResetChip;
YM_Update = YM2612Update;
YM_Write = YM2612Write;
/* chip is running at VCLK / 144 = MCLK / 7 / 144 */
fm_cycles_ratio = 144 * 7;
}
else
{
/* YM2413 */
YM2413Init();
YM_Reset = YM2413ResetChip;
YM_Update = YM2413Update;
YM_Write = YM2413Write;
/* chip is running at ZCLK / 72 = MCLK / 15 / 72 */
fm_cycles_ratio = 72 * 15;
}
/* Initialize PSG chip */
psg_init((system_hw == SYSTEM_SG) ? PSG_DISCRETE : PSG_INTEGRATED);
}
void sound_reset(void)
{
/* reset sound chips */
YM_Reset();
psg_reset();
psg_config(0, config.psg_preamp, 0xff);
/* reset FM buffer ouput */
fm_last[0] = fm_last[1] = 0;
/* reset FM buffer pointer */
fm_ptr = fm_buffer;
/* reset FM cycle counters */
fm_cycles_start = fm_cycles_count = 0;
}
int sound_update(unsigned int cycles)
{
int prev_l, prev_r, preamp, time, l, r, *ptr;
/* Run PSG chip until end of frame */
psg_end_frame(cycles);
/* Run FM chip until end of frame */
fm_update(cycles);
/* FM output pre-amplification */
preamp = config.fm_preamp;
/* FM frame initial timestamp */
time = fm_cycles_start;
/* Restore last FM outputs from previous frame */
prev_l = fm_last[0];
prev_r = fm_last[1];
/* FM buffer start pointer */
ptr = fm_buffer;
/* flush FM samples */
if (config.hq_fm)
{
/* high-quality Band-Limited synthesis */
do
{
/* left & right channels */
l = ((*ptr++ * preamp) / 100);
r = ((*ptr++ * preamp) / 100);
blip_add_delta(snd.blips[0], time, l-prev_l, r-prev_r);
prev_l = l;
prev_r = r;
/* increment time counter */
time += fm_cycles_ratio;
}
while (time < cycles);
}
else
{
/* faster Linear Interpolation */
do
{
/* left & right channels */
l = ((*ptr++ * preamp) / 100);
r = ((*ptr++ * preamp) / 100);
blip_add_delta_fast(snd.blips[0], time, l-prev_l, r-prev_r);
prev_l = l;
prev_r = r;
/* increment time counter */
time += fm_cycles_ratio;
}
while (time < cycles);
}
/* reset FM buffer pointer */
fm_ptr = fm_buffer;
/* save last FM output for next frame */
fm_last[0] = prev_l;
fm_last[1] = prev_r;
/* adjust FM cycle counters for next frame */
fm_cycles_count = fm_cycles_start = time - cycles;
/* end of blip buffer time frame */
blip_end_frame(snd.blips[0], cycles);
/* return number of available samples */
return blip_samples_avail(snd.blips[0]);
}
int sound_context_save(uint8 *state)
{
int bufferptr = 0;
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
bufferptr = YM2612SaveContext(state);
}
else
{
save_param(YM2413GetContextPtr(),YM2413GetContextSize());
}
bufferptr += psg_context_save(&state[bufferptr]);
save_param(&fm_cycles_start,sizeof(fm_cycles_start));
return bufferptr;
}
int sound_context_load(uint8 *state)
{
int bufferptr = 0;
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
bufferptr = YM2612LoadContext(state);
YM2612Config(config.dac_bits);
}
else
{
load_param(YM2413GetContextPtr(),YM2413GetContextSize());
}
bufferptr += psg_context_load(&state[bufferptr]);
load_param(&fm_cycles_start,sizeof(fm_cycles_start));
fm_cycles_count = fm_cycles_start;
return bufferptr;
}
void fm_reset(unsigned int cycles)
{
/* synchronize FM chip with CPU */
fm_update(cycles);
/* reset FM chip */
YM_Reset();
}
void fm_write(unsigned int cycles, unsigned int address, unsigned int data)
{
/* synchronize FM chip with CPU (on data port write only) */
if (address & 1)
{
fm_update(cycles);
}
/* write FM register */
YM_Write(address, data);
}
unsigned int fm_read(unsigned int cycles, unsigned int address)
{
/* synchronize FM chip with CPU */
fm_update(cycles);
/* read FM status (YM2612 only) */
return YM2612Read();
}