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https://github.com/ekeeke/Genesis-Plus-GX.git
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354 lines
9.3 KiB
C
354 lines
9.3 KiB
C
/***************************************************************************************
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* Genesis Plus
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* Sound Hardware
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*
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* Copyright (C) 1998-2003 Charles Mac Donald (original code)
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* Copyright (C) 2007-2016 Eke-Eke (Genesis Plus GX)
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*
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* Redistribution and use of this code or any derivative works are permitted
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* provided that the following conditions are met:
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*
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* - Redistributions may not be sold, nor may they be used in a commercial
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* product or activity.
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*
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* - Redistributions that are modified from the original source must include the
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* complete source code, including the source code for all components used by a
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* binary built from the modified sources. However, as a special exception, the
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* source code distributed need not include anything that is normally distributed
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* (in either source or binary form) with the major components (compiler, kernel,
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* and so on) of the operating system on which the executable runs, unless that
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* component itself accompanies the executable.
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*
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* - Redistributions must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************************/
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#include "shared.h"
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#include "blip_buf.h"
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/* FM output buffer (large enough to hold a whole frame at original chips rate) */
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static int fm_buffer[1080 * 2 * 24];
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static int fm_last[2];
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static int *fm_ptr;
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/* Cycle-accurate FM samples */
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static uint32 fm_cycles_ratio;
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static uint32 fm_cycles_start;
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static uint32 fm_cycles_count;
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/* YM chip function pointers */
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static void (*YM_Reset)(void);
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static void (*YM_Update)(int *buffer, int length);
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static void (*YM_Write)(unsigned int a, unsigned int v);
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static unsigned int (*YM_Read)(unsigned int a);
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static ym3438_t ym3438;
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static int ym3438_accm[24][2];
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static int ym3438_sample[2];
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static unsigned int ym3438_cycles;
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static int ym2612_core;
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void YM3438_Reset(void)
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{
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OPN2_Reset(&ym3438);
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}
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void YM3438_Update(int *buffer, int length)
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{
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int i, j;
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for (i = 0; i < length; i++)
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{
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OPN2_Clock(&ym3438, ym3438_accm[ym3438_cycles]);
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ym3438_cycles = (ym3438_cycles + 1) % 24;
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if (ym3438_cycles == 0)
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{
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ym3438_sample[0] = 0;
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ym3438_sample[1] = 0;
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for (j = 0; j < 24; j++)
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{
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ym3438_sample[0] += ym3438_accm[j][0];
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ym3438_sample[1] += ym3438_accm[j][1];
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}
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}
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*buffer++ = ym3438_sample[0] * 8;
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*buffer++ = ym3438_sample[1] * 8;
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}
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}
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void YM3438_Write(unsigned int a, unsigned int v)
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{
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OPN2_Write(&ym3438, a, v);
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}
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unsigned int YM3438_Read(unsigned int a)
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{
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OPN2_Read(&ym3438, a);
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}
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/* Run FM chip until required M-cycles */
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INLINE void fm_update(unsigned int cycles)
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{
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if (cycles > fm_cycles_count)
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{
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/* number of samples to run */
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unsigned int samples = (cycles - fm_cycles_count + fm_cycles_ratio - 1) / fm_cycles_ratio;
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/* run FM chip to sample buffer */
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YM_Update(fm_ptr, samples);
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/* update FM buffer pointer */
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fm_ptr += (samples << 1);
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/* update FM cycle counter */
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fm_cycles_count += samples * fm_cycles_ratio;
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}
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}
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void sound_init( void )
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{
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/* Initialize FM chip */
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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/* YM2612 */
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ym2612_core = config.ym2612;
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if (config.ym2612)
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{
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// Nuked OPN2
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memset(&ym3438, 0, sizeof(ym3438));
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memset(&ym3438_sample, 0, sizeof(ym3438_sample));
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memset(&ym3438_accm, 0, sizeof(ym3438_accm));
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YM_Reset = YM3438_Reset;
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YM_Update = YM3438_Update;
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YM_Write = YM3438_Write;
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YM_Read = YM3438_Read;
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/* chip is running at VCLK / 6 = MCLK / 7 / 6 */
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fm_cycles_ratio = 6 * 7;
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}
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else
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{
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// MAME
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YM2612Init();
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YM2612Config(config.dac_bits);
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YM_Reset = YM2612ResetChip;
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YM_Update = YM2612Update;
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YM_Write = YM2612Write;
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YM_Read = YM2612Read;
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/* chip is running at VCLK / 144 = MCLK / 7 / 144 */
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fm_cycles_ratio = 144 * 7;
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}
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}
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else
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{
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/* YM2413 */
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YM2413Init();
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YM_Reset = YM2413ResetChip;
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YM_Update = YM2413Update;
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YM_Write = YM2413Write;
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YM_Read = NULL;
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/* chip is running at ZCLK / 72 = MCLK / 15 / 72 */
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fm_cycles_ratio = 72 * 15;
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}
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/* Initialize PSG chip */
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psg_init((system_hw == SYSTEM_SG) ? PSG_DISCRETE : PSG_INTEGRATED);
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}
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void sound_reset(void)
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{
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/* reset sound chips */
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YM_Reset();
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psg_reset();
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psg_config(0, config.psg_preamp, 0xff);
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/* reset FM buffer ouput */
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fm_last[0] = fm_last[1] = 0;
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/* reset FM buffer pointer */
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fm_ptr = fm_buffer;
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/* reset FM cycle counters */
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fm_cycles_start = fm_cycles_count = 0;
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}
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int sound_update(unsigned int cycles)
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{
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int prev_l, prev_r, preamp, time, l, r, *ptr;
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/* Run PSG chip until end of frame */
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psg_end_frame(cycles);
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/* Run FM chip until end of frame */
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fm_update(cycles);
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/* FM output pre-amplification */
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preamp = config.fm_preamp;
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/* FM frame initial timestamp */
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time = fm_cycles_start;
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/* Restore last FM outputs from previous frame */
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prev_l = fm_last[0];
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prev_r = fm_last[1];
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/* FM buffer start pointer */
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ptr = fm_buffer;
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/* flush FM samples */
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if (config.hq_fm)
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{
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/* high-quality Band-Limited synthesis */
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do
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{
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/* left & right channels */
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l = ((*ptr++ * preamp) / 100);
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r = ((*ptr++ * preamp) / 100);
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blip_add_delta(snd.blips[0], time, l-prev_l, r-prev_r);
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prev_l = l;
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prev_r = r;
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/* increment time counter */
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time += fm_cycles_ratio;
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}
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while (time < cycles);
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}
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else
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{
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/* faster Linear Interpolation */
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do
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{
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/* left & right channels */
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l = ((*ptr++ * preamp) / 100);
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r = ((*ptr++ * preamp) / 100);
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blip_add_delta_fast(snd.blips[0], time, l-prev_l, r-prev_r);
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prev_l = l;
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prev_r = r;
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/* increment time counter */
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time += fm_cycles_ratio;
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}
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while (time < cycles);
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}
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/* reset FM buffer pointer */
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fm_ptr = fm_buffer;
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/* save last FM output for next frame */
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fm_last[0] = prev_l;
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fm_last[1] = prev_r;
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/* adjust FM cycle counters for next frame */
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fm_cycles_count = fm_cycles_start = time - cycles;
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/* end of blip buffer time frame */
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blip_end_frame(snd.blips[0], cycles);
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/* return number of available samples */
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return blip_samples_avail(snd.blips[0]);
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}
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int sound_context_save(uint8 *state)
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{
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int bufferptr = 0;
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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if (ym2612_core)
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{
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save_param(&ym3438, sizeof(ym3438));
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save_param(&ym3438_accm, sizeof(ym3438_accm));
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save_param(&ym3438_sample, sizeof(ym3438_sample));
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save_param(&ym3438_cycles, sizeof(ym3438_cycles));
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}
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else
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{
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bufferptr = YM2612SaveContext(state);
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}
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}
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else
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{
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save_param(YM2413GetContextPtr(),YM2413GetContextSize());
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}
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bufferptr += psg_context_save(&state[bufferptr]);
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save_param(&fm_cycles_start,sizeof(fm_cycles_start));
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return bufferptr;
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}
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int sound_context_load(uint8 *state)
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{
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int bufferptr = 0;
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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if (ym2612_core)
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{
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load_param(&ym3438, sizeof(ym3438));
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load_param(&ym3438_accm, sizeof(ym3438_accm));
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load_param(&ym3438_sample, sizeof(ym3438_sample));
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load_param(&ym3438_cycles, sizeof(ym3438_cycles));
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}
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else
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{
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bufferptr = YM2612LoadContext(state);
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YM2612Config(config.dac_bits);
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}
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}
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else
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{
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load_param(YM2413GetContextPtr(),YM2413GetContextSize());
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}
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bufferptr += psg_context_load(&state[bufferptr]);
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load_param(&fm_cycles_start,sizeof(fm_cycles_start));
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fm_cycles_count = fm_cycles_start;
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return bufferptr;
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}
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void fm_reset(unsigned int cycles)
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{
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/* synchronize FM chip with CPU */
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fm_update(cycles);
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/* reset FM chip */
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YM_Reset();
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}
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void fm_write(unsigned int cycles, unsigned int address, unsigned int data)
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{
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/* synchronize FM chip with CPU */
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fm_update(cycles);
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/* write FM register */
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YM_Write(address, data);
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}
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unsigned int fm_read(unsigned int cycles, unsigned int address)
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{
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/* synchronize FM chip with CPU */
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fm_update(cycles);
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/* read FM status (YM2612 only) */
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return YM_Read(address);
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}
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