nsf.c

linux下的MPEG1

/*
** Nofrendo (c) 1998-2000 Matthew Conte ([e-mail])
**
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of version 2 of the GNU Library General 
** Public License as published by the Free Software Foundation.
**
** 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 
** Library General Public License for more details.  To obtain a 
** copy of the GNU Library General Public License, write to the Free 
** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**
** Any permitted reproduction of these routines, in whole or in part,
** must bear this legend.
**
**
** nsf.c
**
** NSF loading/saving related functions
** $Id: nsf.c,v 1.4 2006/09/26 00:52:17 dgp85 Exp $
*/

#include <stdio.h>
#include <string.h>
#include "types.h"
#include "nsf.h"
#include "log.h"
#include "nes6502.h"
#include "nes_apu.h"
#include "vrcvisnd.h"
#include "vrc7_snd.h"
#include "mmc5_snd.h"
#include "fds_snd.h"

/* TODO: bleh! should encapsulate in NSF */
#define  MAX_ADDRESS_HANDLERS    32
static nes6502_memread nsf_readhandler[MAX_ADDRESS_HANDLERS];
static nes6502_memwrite nsf_writehandler[MAX_ADDRESS_HANDLERS];

static nsf_t *cur_nsf = NULL;

static void nsf_setcontext(nsf_t *nsf)
{
   ASSERT(nsf);
   cur_nsf = nsf;
}

static uint8 read_mirrored_ram(uint32 address)
{
   return cur_nsf->cpu->mem_page[0][address & 0x7FF];
}

static void write_mirrored_ram(uint32 address, uint8 value)
{
   cur_nsf->cpu->mem_page[0][address & 0x7FF] = value;
}

/* can be used for both banked and non-bankswitched NSFs */
static void nsf_bankswitch(uint32 address, uint8 value)
{
   int cpu_page;
   uint8 *offset;

   cpu_page = address & 0x0F;
   offset = (cur_nsf->data - (cur_nsf->load_addr & 0x0FFF)) + (value << 12);

   nes6502_getcontext(cur_nsf->cpu);
   cur_nsf->cpu->mem_page[cpu_page] = offset;
   nes6502_setcontext(cur_nsf->cpu);
}

static nes6502_memread default_readhandler[] =
{
   { 0x0800, 0x1FFF, read_mirrored_ram },
   { 0x4000, 0x4017, apu_read },
   { -1,     -1,     NULL }
};

static nes6502_memwrite default_writehandler[] =
{
   { 0x0800, 0x1FFF, write_mirrored_ram },
   { 0x4000, 0x4017, apu_write },
   { 0x5FF6, 0x5FFF, nsf_bankswitch },
   { -1,     -1,     NULL}
};

static uint8 invalid_read(uint32 address)
{
#ifdef NOFRENDO_DEBUG
   log_printf("filthy NSF read from $%04X\n", address);
#endif /* NOFRENDO_DEBUG */

   return 0xFF;
}

static void invalid_write(uint32 address, uint8 value)
{
#ifdef NOFRENDO_DEBUG
   log_printf("filthy NSF tried to write $%02X to $%04X\n", value, address);
#endif /* NOFRENDO_DEBUG */
}

/* set up the address handlers that the CPU uses */
static void build_address_handlers(nsf_t *nsf)
{
   int count, num_handlers;

   memset(nsf_readhandler, 0, sizeof(nsf_readhandler));
   memset(nsf_writehandler, 0, sizeof(nsf_writehandler));
 
   num_handlers = 0;
   for (count = 0; num_handlers < MAX_ADDRESS_HANDLERS; count++, num_handlers++)
   {
      if (NULL == default_readhandler[count].read_func)
         break;

      memcpy(&nsf_readhandler[num_handlers], &default_readhandler[count],
             sizeof(nes6502_memread));
   }

   if (nsf->apu->ext)
   {
      if (NULL != nsf->apu->ext->mem_read)
      {
         for (count = 0; num_handlers < MAX_ADDRESS_HANDLERS; count++, num_handlers++)
         {
            if (NULL == nsf->apu->ext->mem_read[count].read_func)
               break;

            memcpy(&nsf_readhandler[num_handlers], &nsf->apu->ext->mem_read[count],
                   sizeof(nes6502_memread));
         }
      }
   }

   /* catch-all for bad reads */
   nsf_readhandler[num_handlers].min_range = 0x2000; /* min address */
   nsf_readhandler[num_handlers].max_range = 0x5BFF; /* max address */
   nsf_readhandler[num_handlers].read_func = invalid_read; /* handler */
   num_handlers++;
   nsf_readhandler[num_handlers].min_range = -1;
   nsf_readhandler[num_handlers].max_range = -1;
   nsf_readhandler[num_handlers].read_func = NULL;
   num_handlers++;
   ASSERT(num_handlers <= MAX_ADDRESS_HANDLERS);

   num_handlers = 0;
   for (count = 0; num_handlers < MAX_ADDRESS_HANDLERS; count++, num_handlers++)
   {
      if (NULL == default_writehandler[count].write_func)
         break;

      memcpy(&nsf_writehandler[num_handlers], &default_writehandler[count],
             sizeof(nes6502_memwrite));
   }

   if (nsf->apu->ext)
   {
      if (NULL != nsf->apu->ext->mem_write)
      {
         for (count = 0; num_handlers < MAX_ADDRESS_HANDLERS; count++, num_handlers++)
         {
            if (NULL == nsf->apu->ext->mem_write[count].write_func)
               break;

            memcpy(&nsf_writehandler[num_handlers], &nsf->apu->ext->mem_write[count],
                   sizeof(nes6502_memwrite));
         }
      }
   }

   /* catch-all for bad writes */
   nsf_writehandler[num_handlers].min_range = 0x2000; /* min address */
   nsf_writehandler[num_handlers].max_range = 0x5BFF; /* max address */
   nsf_writehandler[num_handlers].write_func = invalid_write; /* handler */
   num_handlers++;
   /* protect region at $8000-$FFFF */
   nsf_writehandler[num_handlers].min_range = 0x8000; /* min address */
   nsf_writehandler[num_handlers].max_range = 0xFFFF; /* max address */
   nsf_writehandler[num_handlers].write_func = invalid_write; /* handler */
   num_handlers++;
   nsf_writehandler[num_handlers].min_range = -1;
   nsf_writehandler[num_handlers].max_range = -1;
   nsf_writehandler[num_handlers].write_func = NULL;
   num_handlers++;
   ASSERT(num_handlers <= MAX_ADDRESS_HANDLERS);
}

#define  NSF_ROUTINE_LOC   0x5000

/* sets up a simple loop that calls the desired routine and spins */
static void nsf_setup_routine(uint32 address, uint8 a_reg, uint8 x_reg)
{
   uint8 *mem;

   nes6502_getcontext(cur_nsf->cpu);
   mem = cur_nsf->cpu->mem_page[NSF_ROUTINE_LOC >> 12] + (NSF_ROUTINE_LOC & 0x0FFF);

   /* our lovely 4-byte 6502 NSF player */
   mem[0] = 0x20;            /* JSR address */
   mem[1] = address & 0xFF;
   mem[2] = address >> 8;
   mem[3] = 0xF2;            /* JAM (cpu kill op) */

   cur_nsf->cpu->pc_reg = NSF_ROUTINE_LOC;
   cur_nsf->cpu->a_reg = a_reg;
   cur_nsf->cpu->x_reg = x_reg;
   cur_nsf->cpu->y_reg = 0;
   cur_nsf->cpu->s_reg = 0xFF;

   nes6502_setcontext(cur_nsf->cpu);
}

/* retrieve any external soundchip driver */
static apuext_t *nsf_getext(nsf_t *nsf)
{
   switch (nsf->ext_sound_type)
   {
   case EXT_SOUND_VRCVI:
      return &vrcvi_ext;

   case EXT_SOUND_VRCVII:
      return &vrc7_ext;

   case EXT_SOUND_FDS:
      return &fds_ext;

   case EXT_SOUND_MMC5:
      return &mmc5_ext;

   case EXT_SOUND_NAMCO106:
   case EXT_SOUND_SUNSOFT_FME07:
   case EXT_SOUND_NONE:
   default:
      return NULL;
   }
}

static void nsf_inittune(nsf_t *nsf)
{
   uint8 bank, x_reg;
   uint8 start_bank, num_banks;

   memset(nsf->cpu->mem_page[0], 0, 0x800);
   memset(nsf->cpu->mem_page[6], 0, 0x1000);
   memset(nsf->cpu->mem_page[7], 0, 0x1000);

   if (nsf->bankswitched)
   {
      /* the first hack of the NSF spec! */
      if (EXT_SOUND_FDS == nsf->ext_sound_type)
      {
         nsf_bankswitch(0x5FF6, nsf->bankswitch_info[6]);
         nsf_bankswitch(0x5FF7, nsf->bankswitch_info[7]);
      }

      for (bank = 0; bank < 8; bank++)
         nsf_bankswitch(0x5FF8 + bank, nsf->bankswitch_info[bank]);
   }
   else
   {
      /* not bankswitched, just page in our standard stuff */
      ASSERT(nsf->load_addr + nsf->length <= 0x10000);

      /* avoid ripper filth */
      for (bank = 0; bank < 8; bank++)
         nsf_bankswitch(0x5FF8 + bank, bank);

      start_bank = nsf->load_addr >> 12;
      num_banks = ((nsf->load_addr + nsf->length - 1) >> 12) - start_bank + 1;

      for (bank = 0; bank < num_banks; bank++)
         nsf_bankswitch(0x5FF0 + start_bank + bank, bank);
   }

   /* determine PAL/NTSC compatibility shite */
   if (nsf->pal_ntsc_bits & NSF_DEDICATED_PAL)
      x_reg = 1;
   else   
      x_reg = 0;

   /* execute 1 frame or so; let init routine run free */
   nsf_setup_routine(nsf->init_addr, (uint8) (nsf->current_song - 1), x_reg);
   nes6502_execute((int) NES_FRAME_CYCLES);
}

void nsf_frame(nsf_t *nsf)
{
   //nsf_setcontext(nsf); /* future expansion =) */

   /* one frame of NES processing */
   nsf_setup_routine(nsf->play_addr, 0, 0);
   nes6502_execute((int) NES_FRAME_CYCLES);
}

/* Deallocate memory */
static void nes_shutdown(nsf_t *nsf)
{
   int i;

   ASSERT(nsf);
   
   if (nsf->cpu)
   {
      if (nsf->cpu->mem_page[0])
         free(nsf->cpu->mem_page[0]);
      for (i = 5; i <= 7; i++)
      {
         if (nsf->cpu->mem_page[i])
            free(nsf->cpu->mem_page[i]);
      }
      free(nsf->cpu);
   }
}