The-Homebrew-Cloud/Genesis-Plus-GX
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1cfb7e6f44
Genesis-Plus-GX/source/system.c
ekeeke31 1cfb7e6f44 +implemented Blip Buffer linear interpolation in SN76489 core 
+optimized SN76489 core
+added configurable SN76489 Noise boost
+added savestate version check
2009-05-27 14:07:14 +00:00

474 lines
13 KiB
C
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/***************************************************************************************
* Genesis Plus
* Main Emulation
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
* Eke-Eke (2007,2008,2009), additional code & fixes for the GCN/Wii port
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
****************************************************************************************/
#include "shared.h"
#include "samplerate.h"
#include "eq.h"
#define SND_SIZE (snd.buffer_size * sizeof(int16))
/* Global variables */
t_bitmap bitmap;
t_snd snd;
uint32 count_m68k;
uint32 line_m68k;
uint32 hint_m68k;
uint32 count_z80;
uint32 line_z80;
int32 current_z80;
uint8 system_hw;
/****************************************************************
* AUDIO equalizer
****************************************************************/
static EQSTATE eq;
void audio_init_equalizer(void)
{
init_3band_state(&eq,880,5000,snd.sample_rate);
audio_set_equalizer();
}
void audio_set_equalizer(void)
{
eq.lg = (double)(config.lg);
eq.mg = (double)(config.mg);
eq.hg = (double)(config.hg);
}
/****************************************************************
* AUDIO stream update
****************************************************************/
static int ll, rr;
static SRC_DATA src_data;
void audio_update (int size)
{
int i;
int l, r;
int psg_preamp = config.psg_preamp;
int fm_preamp = config.fm_preamp;
int filter = config.filter;
#ifndef DOS
int16 *sb = (int16 *) soundbuffer[mixbuffer];
#endif
int *fm_l = snd.fm.buffer[0];
int *fm_r = snd.fm.buffer[1];
int16 *psg = snd.psg.buffer;
float *src = src_data.data_out;
double scaled_value;
/* resampling */
if (src)
{
src_data.output_frames = size;
src_data.input_frames = (int)((double)size / src_data.src_ratio + 0.5);
sound_update(src_data.input_frames,size);
src_simple(&src_data,(config.hq_fm&1) ? SRC_LINEAR : SRC_SINC_FASTEST, 2);
}
else sound_update(size,size);
/* mix samples */
for (i = 0; i < size; i ++)
{
/* PSG samples (mono) */
l = r = (((int)*psg++) * psg_preamp)/100;
/* FM samples (stereo) */
if (src)
{
/* left channel */
scaled_value = (*src++) * (8.0 * 0x10000000);
if (scaled_value >= (1.0 * 0x7FFFFFFF))
l = 0x7fffffff;
else if (scaled_value <= (-8.0 * 0x10000000))
l = -1 - 0x7fffffff;
else
l += (lrint(scaled_value) * fm_preamp)/100;
/* right channel */
scaled_value = (*src++) * (8.0 * 0x10000000);
if (scaled_value >= (1.0 * 0x7FFFFFFF))
r = 0x7fffffff;
else if (scaled_value <= (-8.0 * 0x10000000))
r = -1 - 0x7fffffff;
else
r += (lrint(scaled_value) * fm_preamp)/100;
}
else
{
l += (*fm_l * fm_preamp)/100;
r += (*fm_r * fm_preamp)/100;
*fm_l++ = 0;
*fm_r++ = 0;
}
/* filtering */
if (filter & 1)
{
/* single-pole low-pass filter (6 dB/octave) */
l = (ll + l) >> 1;
r = (rr + r) >> 1;
ll = l;
rr = r;
}
else if (filter & 2)
{
/* 3 Band EQ */
l = do_3band(&eq,l);
r = do_3band(&eq,r);
}
/* clipping */
if (l > 32767) l = 32767;
else if (l < -32768) l = -32768;
if (r > 32767) r = 32767;
else if (r < -32768) r = -32768;
/* update sound buffer */
#ifdef DOS
snd.buffer[0][i] = l;
snd.buffer[1][i] = r;
#elif LSB_FIRST
*sb++ = l;
*sb++ = r;
#else
*sb++ = r;
*sb++ = l;
#endif
}
}
/****************************************************************
* AUDIO System initialization
****************************************************************/
int audio_init (int rate)
{
/* Shutdown first */
audio_shutdown();
/* Clear the sound data context */
memset(&snd, 0, sizeof (snd));
memset(&src_data, 0, sizeof(src_data));
/* Make sure the requested sample rate is valid */
if (!rate || ((rate < 8000) | (rate > 48000))) return (-1);
snd.sample_rate = rate;
/* Calculate the sound buffer size (for one frame) */
snd.buffer_size = (rate / vdp_rate) + 8;
#ifdef DOS
/* output buffers */
snd.buffer[0] = (int16 *) malloc(SND_SIZE);
snd.buffer[1] = (int16 *) malloc(SND_SIZE);
if (!snd.buffer[0] || !snd.buffer[1]) return (-1);
#endif
/* SRC */
if (config.hq_fm)
{
/* SRC ratio (YM2612 original samplerate is VCLK/144) */
src_data.src_ratio = ((double)rate * 144.0) / ((double) vdp_rate * (double)m68cycles_per_line * (double)lines_per_frame);
/* max. output */
src_data.output_frames = snd.buffer_size;
/* max. input */
snd.fm.size = (int)((double)src_data.output_frames / src_data.src_ratio + 0.5);
src_data.input_frames = snd.fm.size;
/* SRC buffers */
src_data.data_in = (float *) malloc(snd.fm.size*2*sizeof(float));
src_data.data_out = (float *) malloc(snd.buffer_size*2*sizeof(float));
if (!src_data.data_in || !src_data.data_out) return (-1);
snd.fm.src_buffer = src_data.data_in;
}
else
{
/* YM2612 stream buffers */
snd.fm.size = snd.buffer_size;
snd.fm.buffer[0] = (int *)malloc (snd.fm.size * sizeof(int));
snd.fm.buffer[1] = (int *)malloc (snd.fm.size * sizeof(int));
if (!snd.fm.buffer[0] || !snd.fm.buffer[1]) return (-1);
}
/* SN76489 stream buffers */
snd.psg.buffer = (int16 *)malloc (SND_SIZE);
if (!snd.psg.buffer) return (-1);
/* 3 band EQ */
audio_init_equalizer();
/* Set audio enable flag */
snd.enabled = 1;
/* Initialize Sound Chips emulation */
sound_init(rate);
return (0);
}
/****************************************************************
* AUDIO System shutdown
****************************************************************/
void audio_shutdown(void)
{
/* free sound buffers */
if (snd.buffer[0]) free(snd.buffer[0]);
if (snd.buffer[1]) free(snd.buffer[1]);
if (snd.fm.buffer[0]) free(snd.fm.buffer[0]);
if (snd.fm.buffer[1]) free(snd.fm.buffer[1]);
if (snd.psg.buffer) free(snd.psg.buffer);
/* SRC*/
if (src_data.data_in) free(src_data.data_in);
if (src_data.data_out) free(src_data.data_out);
}
/****************************************************************
* Virtual Genesis initialization
****************************************************************/
void system_init (void)
{
gen_init ();
vdp_init ();
render_init ();
cart_hw_init();
}
/****************************************************************
* Virtual Genesis Hard Reset
****************************************************************/
void system_reset (void)
{
/* Cartridge Hardware */
cart_hw_reset();
/* Genesis Hardware */
gen_reset (1);
vdp_reset ();
render_reset ();
io_reset();
SN76489_Reset();
/* Sound Buffers */
if (snd.psg.buffer) memset (snd.psg.buffer, 0, SND_SIZE);
if (snd.fm.buffer[0]) memset (snd.fm.buffer[0], 0, snd.fm.size * sizeof(int));
if (snd.fm.buffer[1]) memset (snd.fm.buffer[1], 0, snd.fm.size * sizeof(int));
}
/****************************************************************
* Virtual Genesis shutdown
****************************************************************/
void system_shutdown (void)
{
gen_shutdown ();
vdp_shutdown ();
render_shutdown ();
SN76489_Shutdown();
}
/****************************************************************
* Virtual Genesis Frame emulation
****************************************************************/
int system_frame (int do_skip)
{
if (!gen_running)
{
update_input();
return 0;
}
uint32 aim_m68k = 0;
uint32 aim_z80 = 0;
/* reset cycles counts */
count_m68k = 0;
count_z80 = 0;
fifo_write_cnt = 0;
fifo_lastwrite = 0;
/* update display settings */
int line;
int reset = resetline;
int vdp_height = bitmap.viewport.h;
int end_line = vdp_height + bitmap.viewport.y;
int start_line = lines_per_frame - bitmap.viewport.y;
int old_interlaced = interlaced;
interlaced = (reg[12] & 2) >> 1;
if (old_interlaced != interlaced)
{
bitmap.viewport.changed |= 1;
im2_flag = ((reg[12] & 6) == 6);
odd_frame = 1;
}
odd_frame ^= 1;
#ifdef NGC
if (bitmap.viewport.changed & 2)
{
/* Update the width of the viewport */
bitmap.viewport.w = (reg[12] & 1) ? 320 : 256;
bitmap.viewport.changed = 1;
/* Update clipping */
window_clip(reg[12],reg[17]);
}
#endif
/* clear VBLANK and DMA flags */
status &= 0xFFF5;
/* even/odd field flag (interlaced modes only) */
if (odd_frame && interlaced) status |= 0x0010;
else status &= 0xFFEF;
/* reload HCounter */
int h_counter = reg[10];
/* parse sprites for line 0 (done on last line) */
parse_satb (0x80);
/* process scanlines */
for (line = 0; line < lines_per_frame; line ++)
{
/* update VCounter */
v_counter = line;
/* update 6-Buttons or Menacer */
input_update();
/* update CPU cycle counters */
hint_m68k = count_m68k;
line_m68k = aim_m68k;
line_z80 = aim_z80;
aim_z80 += z80cycles_per_line;
aim_m68k += m68cycles_per_line;
/* Soft Reset ? */
if (line == reset)
{
#ifdef NGC
/* wait for RESET button to be released */
while (SYS_ResetButtonDown());
#endif
gen_reset(0);
}
/* active display */
if (line <= vdp_height)
{
/* H Interrupt */
if(--h_counter < 0)
{
h_counter = reg[10];
hint_pending = 1;
if (reg[0] & 0x10) irq_status = (irq_status & 0xff) | 0x14;
/* adjust timings to take further decrement in account (see below) */
if ((line != 0) || (h_counter == 0)) aim_m68k += 36;
}
/* HINT will be triggered on next line, approx. 36 cycles before VDP starts line rendering */
/* during this period, any VRAM/CRAM/VSRAM writes should NOT be taken in account before next line */
/* as a result, current line is shortened */
/* fix Lotus 1, Lotus 2 RECS, Striker, Zero the Kamikaze Squirell */
if ((line < vdp_height) && (h_counter == 0)) aim_m68k -= 36;
/* update DMA timings */
if (dma_length) dma_update();
/* vertical retrace */
if (line == vdp_height)
{
/* render overscan */
if ((line < end_line) && (!do_skip)) render_line(line, 1);
/* update inputs (doing this here fix Warriors of Eternal Sun) */
update_input();
/* set VBLANK flag */
status |= 0x08;
/* Z80 interrupt is 16ms period (one frame) and 64us length (one scanline) */
zirq = 1;
z80_set_irq_line(0, ASSERT_LINE);
/* delay between HINT, VBLANK and VINT (Dracula, OutRunners, VR Troopers) */
m68k_run(line_m68k + 84);
if (zreset && !zbusreq)
{
current_z80 = line_z80 + 39 - count_z80;
if (current_z80 > 0) count_z80 += z80_execute(current_z80);
}
else count_z80 = line_z80 + 39;
/* V Interrupt */
status |= 0x80;
vint_pending = 1;
/* 36 cycles latency after VINT occurence flag (Ex-Mutants, Tyrant) */
if (reg[1] & 0x20) irq_status = (irq_status & 0xff) | 0x2416;
}
else if (!do_skip)
{
/* render scanline and parse sprites for line n+1 */
render_line(line, 0);
if (line < (vdp_height-1)) parse_satb(0x81 + line);
}
}
else
{
/* update DMA timings */
if (dma_length) dma_update();
/* render overscan */
if ((!do_skip) && ((line < end_line) || (line >= start_line))) render_line(line, 1);
/* clear any pending Z80 interrupt */
if (zirq)
{
zirq = 0;
z80_set_irq_line(0, CLEAR_LINE);
}
}
/* process line */
m68k_run(aim_m68k);
if (zreset == 1 && zbusreq == 0)
{
current_z80 = aim_z80 - count_z80;
if (current_z80 > 0) count_z80 += z80_execute(current_z80);
}
else count_z80 = aim_z80;
/* SVP chip */
if (svp) ssp1601_run(SVP_cycles);
}
return gen_running;
}
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