sb.c

SFC游戏模拟器 snes9x 1.43 的原代码

/*******************************************************************************
  Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
 
  (c) Copyright 1996 - 2002 Gary Henderson ([e-mail]) and
                            Jerremy Koot ([e-mail])

  (c) Copyright 2001 - 2004 John Weidman ([e-mail])

  (c) Copyright 2002 - 2004 Brad Jorsch ([e-mail]),
                            funkyass ([e-mail]),
                            Joel Yliluoma (http://iki.fi/bisqwit/)
                            Kris Bleakley ([e-mail]),
                            Matthew Kendora,
                            Nach ([e-mail]),
                            Peter Bortas ([e-mail]) and
                            zones ([e-mail])

  C4 x86 assembler and some C emulation code
  (c) Copyright 2000 - 2003 zsKnight ([e-mail]),
                            _Demo_ ([e-mail]), and Nach

  C4 C++ code
  (c) Copyright 2003 Brad Jorsch

  DSP-1 emulator code
  (c) Copyright 1998 - 2004 Ivar ([e-mail]), _Demo_, Gary Henderson,
                            John Weidman, neviksti ([e-mail]),
                            Kris Bleakley, Andreas Naive

  DSP-2 emulator code
  (c) Copyright 2003 Kris Bleakley, John Weidman, neviksti, Matthew Kendora, and
                     Lord Nightmare ([e-mail]

  OBC1 emulator code
  (c) Copyright 2001 - 2004 zsKnight, pagefault ([e-mail]) and
                            Kris Bleakley
  Ported from x86 assembler to C by sanmaiwashi

  SPC7110 and RTC C++ emulator code
  (c) Copyright 2002 Matthew Kendora with research by
                     zsKnight, John Weidman, and Dark Force

  S-DD1 C emulator code
  (c) Copyright 2003 Brad Jorsch with research by
                     Andreas Naive and John Weidman
 
  S-RTC C emulator code
  (c) Copyright 2001 John Weidman
  
  ST010 C++ emulator code
  (c) Copyright 2003 Feather, Kris Bleakley, John Weidman and Matthew Kendora

  Super FX x86 assembler emulator code 
  (c) Copyright 1998 - 2003 zsKnight, _Demo_, and pagefault 

  Super FX C emulator code 
  (c) Copyright 1997 - 1999 Ivar, Gary Henderson and John Weidman


  SH assembler code partly based on x86 assembler code
  (c) Copyright 2002 - 2004 Marcus Comstedt ([e-mail]) 

 
  Specific ports contains the works of other authors. See headers in
  individual files.
 
  Snes9x homepage: http://www.snes9x.com
 
  Permission to use, copy, modify and distribute Snes9x in both binary and
  source form, for non-commercial purposes, is hereby granted without fee,
  providing that this license information and copyright notice appear with
  all copies and any derived work.
 
  This software is provided 'as-is', without any express or implied
  warranty. In no event shall the authors be held liable for any damages
  arising from the use of this software.
 
  Snes9x is freeware for PERSONAL USE only. Commercial users should
  seek permission of the copyright holders first. Commercial use includes
  charging money for Snes9x or software derived from Snes9x.
 
  The copyright holders request that bug fixes and improvements to the code
  should be forwarded to them so everyone can benefit from the modifications
  in future versions.
 
  Super NES and Super Nintendo Entertainment System are trademarks of
  Nintendo Co., Limited and its subsidiary companies.
*******************************************************************************/
/*         ______   ___    ___ 
 *        /\  _  \ /\_ \  /\_ \ 
 *        \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___ 
 *         \ \  __ \ \ \ \  \ \ \   /'__`\ /'_ `\/\`'__\/ __`\
 *          \ \ \/\ \ \_\ \_ \_\ \_/\  __//\ \L\ \ \ \//\ \L\ \
 *           \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
 *            \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
 *                                           /\____/
 *                                           \_/__/
 *      By Shawn Hargreaves,
 *      1 Salisbury Road,
 *      Market Drayton,
 *      Shropshire,
 *      England, TF9 1AJ.
 *
 *      Soundblaster driver. Supports DMA driven sample playback (mixing 
 *      up to eight samples at a time) and raw note output to the SB MIDI 
 *      port. The Adlib (FM synth) MIDI playing code is in adlib.c.
 *
 *      Input routines added by Ove Kaaven.
 *
 *      See readme.txt for copyright information.
 */


#ifndef DJGPP
#error This file should only be used by the djgpp version of Allegro
#endif

#include <stdlib.h>
#include <stdio.h>
#include <dos.h>
#include <go32.h>
#include <dpmi.h>
#include <limits.h>
#include <sys/farptr.h>

#include <allegro.h>
#include "sb.h"

#define SB_DMA_BUFFER_SIZE       32

#define DISABLE()   asm volatile ("cli")
#define ENABLE()    asm volatile ("sti")
/* interrupt hander stuff */
#define _map_irq(irq)   (((irq)>7) ? ((irq)+104) : ((irq)+8))
#define _eoi(irq) { outportb(0x20, 0x20); if ((irq)>7) outportb(0xA0, 0x20); }

/* external interface to the digital SB driver */
void sx_sb_exit ();
static int sx_sb_mixer_volume(int volume);
char sx_sb_desc[80] = "not initialised";

/* external interface to the SB midi output driver */

static int sx_sb_in_use = FALSE;             /* is SB being used? */
static int sx_sb_stereo = FALSE;             /* in stereo mode? */
static int sx_sb_16bit = FALSE;              /* in 16 bit mode? */
static int sx_sb_int = -1;                   /* interrupt vector */
static int sx_sb_dsp_ver = -1;               /* SB DSP version */
static int sx_sb_dma8 = -1;                  /* 8-bit DMA channel (SB16) */
static int sx_sb_dma16 = -1;                 /* 16-bit DMA channel (SB16) */
static int sx_sb_hw_dsp_ver = -1;            /* as reported by autodetect */
static int sx_sb_dma_size = -1;              /* size of dma transfer in bytes */
static int sx_sb_dma_mix_size = -1;          /* number of samples to mix */
static int sx_sb_dma_count = 0;              /* need to resync with dma? */
static volatile int sx_sb_semaphore = FALSE; /* reentrant interrupt? */
static int sx_sb_freq = -1;
static int sx_sb_irq = -1;
static int sx_sb_dma = -1;
static int sx_sb_port = -1;
static int sx_sb_mute = 0;
static char * mixbuffer = NULL;

static int sx_sb_sel[2];                     /* selectors for the buffers */
static unsigned long sx_sb_buf[2];           /* pointers to the two buffers */
static int sx_sb_bufnum = 0;                 /* the one currently in use */

static int sx_sb_master_vol;                 /* stored mixer settings */
static int sx_sb_digi_vol;
static int sx_sb_fm_vol;

static void sx_sb_lock_mem();


/* sx_sb_read_dsp:
 *  Reads a byte from the SB DSP chip. Returns -1 if it times out.
 */
static inline volatile int sx_sb_read_dsp()
{
   int x;

   for (x=0; x<0xffff; x++)
      if (inportb(0x0E + sx_sb_port) & 0x80)
	 return inportb(0x0A+sx_sb_port);

   return -1; 
}



/* sx_sb_write_dsp:
 *  Writes a byte to the SB DSP chip. Returns -1 if it times out.
 */
static inline volatile int sx_sb_write_dsp(unsigned char byte)
{
   int x;

   for (x=0; x<0xffff; x++) {
      if (!(inportb(0x0C+sx_sb_port) & 0x80)) {
	 outportb(0x0C+sx_sb_port, byte);
	 return 0;
      }
   }
   return -1; 
}



/* sx_sb_voice:
 *  Turns the SB speaker on or off.
 */
void sx_sb_voice(int state)
{
   if (state) {
      sx_sb_write_dsp(0xD1);

      if (sx_sb_hw_dsp_ver >= 0x300) {       /* set up the mixer */

	 outportb(sx_sb_port+4, 0x22);      /* store master volume */
	 sx_sb_master_vol = inportb(sx_sb_port+5);

	 outportb(sx_sb_port+4, 4);         /* store DAC level */
	 sx_sb_digi_vol = inportb(sx_sb_port+5);

	 outportb(sx_sb_port+4, 0x26);      /* store FM level */
	 sx_sb_fm_vol = inportb(sx_sb_port+5);
      }
   }
   else {
      sx_sb_write_dsp(0xD3);

      if (sx_sb_hw_dsp_ver >= 0x300) {       /* reset previous mixer settings */

	 outportb(sx_sb_port+4, 0x22);      /* restore master volume */
	 outportb(sx_sb_port+5, sx_sb_master_vol);

	 outportb(sx_sb_port+4, 4);         /* restore DAC level */
	 outportb(sx_sb_port+5, sx_sb_digi_vol);

	 outportb(sx_sb_port+4, 0x26);      /* restore FM level */
	 outportb(sx_sb_port+5, sx_sb_fm_vol);
      }
   }
}



/* sx_sb_set_mixer:
 *  Alters the SB-Pro hardware mixer.
 */
int sx_sb_set_mixer(int digi_volume, int midi_volume)
{
   if (sx_sb_hw_dsp_ver < 0x300)
      return -1;

   if (digi_volume >= 0) {                   /* set DAC level */
      outportb(sx_sb_port+4, 4);
      outportb(sx_sb_port+5, (digi_volume & 0xF0) | (digi_volume >> 4));
   }

   if (midi_volume >= 0) {                   /* set FM level */
      outportb(sx_sb_port+4, 0x26);
      outportb(sx_sb_port+5, (midi_volume & 0xF0) | (midi_volume >> 4));
   }

   return 0;
}

/* sx_sb_mixer_volume:
 *  Sets the SB mixer volume for playing digital samples.
 */
static int sx_sb_mixer_volume(int volume)
{
   return sx_sb_set_mixer(volume, -1);
}

/* sx_sb_stereo_mode:
 *  Enables or disables stereo output for SB-Pro.
 */
static void sx_sb_stereo_mode(int enable)
{
   outportb(sx_sb_port+0x04, 0x0E); 
   outportb(sx_sb_port+0x05, (enable ? 2 : 0));
}

/* sx_sb_set_sample_rate:
 *  The parameter is the rate to set in Hz (samples per second).
 */
static void sx_sb_set_sample_rate(unsigned int rate)
{
   if (sx_sb_16bit) {
      sx_sb_write_dsp(0x41);
      sx_sb_write_dsp(rate >> 8);
      sx_sb_write_dsp(rate & 0xff);
   }
   else {
      if (sx_sb_stereo)
	 rate *= 2;

      sx_sb_write_dsp(0x40);
      sx_sb_write_dsp((unsigned char)(256-1000000/rate));
   }
}



/* sx_sb_reset_dsp:
 *  Resets the SB DSP chip, returning -1 on error.
 */
int sx_sb_reset_dsp(int data)
{
   int x;

   outportb(0x06+sx_sb_port, data);

   for (x=0; x<8; x++)
      inportb(0x06+sx_sb_port);

   outportb(0x06+sx_sb_port, 0);

   if (sx_sb_read_dsp() != 0xAA)
      return -1;

   return 0;
}



/* sx_sb_read_dsp_version:
 *  Reads the version number of the SB DSP chip, returning -1 on error.
 */
int sx_sb_read_dsp_version()
{
   int x, y;

   if (sx_sb_hw_dsp_ver > 0)
      return sx_sb_hw_dsp_ver;

   if (sx_sb_port <= 0)
      sx_sb_port = 0x220;

   if (sx_sb_reset_dsp(1) != 0) {
      sx_sb_hw_dsp_ver = -1;
   }
   else {
      sx_sb_write_dsp(0xE1);
      x = sx_sb_read_dsp();
      y = sx_sb_read_dsp();
      sx_sb_hw_dsp_ver = ((x << 8) | y);
   }

   return sx_sb_hw_dsp_ver;
}



/* sx_sb_play_buffer:
 *  Starts a dma transfer of size bytes. On cards capable of it, the
 *  transfer will use auto-initialised dma, so there is no need to call
 *  this routine more than once. On older cards it must be called from
 *  the end-of-buffer handler to switch to the new buffer.
 */
static void sx_sb_play_buffer(int size)
{
   if (sx_sb_dsp_ver <= 0x200) {                /* 8 bit single-shot */
      sx_sb_write_dsp(0x14);
      sx_sb_write_dsp((size-1) & 0xFF);
      sx_sb_write_dsp((size-1) >> 8);
   }
   else if (sx_sb_dsp_ver < 0x400) {            /* 8 bit auto-initialised */
      sx_sb_write_dsp(0x48);
      sx_sb_write_dsp((size-1) & 0xFF);
      sx_sb_write_dsp((size-1) >> 8);
      sx_sb_write_dsp(0x90);
   }
   else {                                    /* 16 bit */
      size /= 2;
      sx_sb_write_dsp(0xB6);
      sx_sb_write_dsp((sx_sb_stereo ? 0x20 : 0x00) + 0x10);
      /*sx_sb_write_dsp(0x20);*/
      sx_sb_write_dsp((size-1) & 0xFF);
      sx_sb_write_dsp((size-1) >> 8);
   }
}

static END_OF_FUNCTION(sx_sb_play_buffer);



/* sx_sb_interrupt:
 *  The SB end-of-buffer interrupt handler. Swaps to the other buffer 
 *  if the card doesn't have auto-initialised dma, and then refills the
 *  buffer that just finished playing.
 */
static int sx_sb_interrupt()
{
   unsigned char isr;

   if (sx_sb_dsp_ver >= 0x400) {
      /* read SB16 ISR mask */
      outportb(sx_sb_port+4, 0x82);
      isr = inportb(sx_sb_port+5) & 7;

      if (isr & 4) {
	 /* MPU-401 interrupt */
	 /*_mpu_poll();*/
	 _eoi(sx_sb_irq);
	 return 0;
      }

      if (!(isr & 3)) {
	 /* unknown interrupt */
	 _eoi(sx_sb_irq);
	 return 0;
      }
   }

   if (sx_sb_dsp_ver <= 0x200) {                /* not auto-initialised */
      _dma_start(sx_sb_dma, sx_sb_buf[1-sx_sb_bufnum], sx_sb_dma_size, FALSE, FALSE);
      sx_sb_play_buffer(sx_sb_dma_size);
   }
   else {                                    /* poll dma position */