/*
** Nofrendo (c) 1998-2000 Matthew Conte (matt@conte.com)
**
**
** 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.
**
**
** map041.c
**
** Mapper #41 (Caltron 6 in 1)
** Implementation by Firebug
** Mapper information courtesy of Kevin Horton
** $Id: map041.c,v 1.2 2001/04/27 14:37:11 neil Exp $
**
*/

#include "../noftypes.h"
#include "../nes_mmc.h"
#include "../nes.h"
#include "../libsnss.h"
#include "../log.h"

static uint8 register_low;
static uint8 register_high;

/*****************************************************/
/* Set 8K CHR bank from the combined register values */
/*****************************************************/
static void map41_set_chr (void)
{
  /* Set the CHR bank from the appropriate register bits */
  mmc_bankvrom (8, 0x0000, ((register_low >> 1) & 0x0C) | (register_high));

  /* Done */
  return;
}

/******************************/
/* Mapper #41: Caltron 6 in 1 */
/******************************/
static void map41_init (void)
{
  /* Both registers set to zero at power on */
  /* TODO: Registers should also be cleared on a soft reset */
  register_low = 0x00;
  register_high = 0x00;
  mmc_bankrom (32, 0x8000, 0x00);
  map41_set_chr ();

  /* Done */
  return;
}

/******************************************/
/* Mapper #41 write handler ($6000-$67FF) */
/******************************************/
static void map41_low_write (uint32 address, uint8 value)
{
  /* Within this range the value written is irrelevant */
  UNUSED (value);

  /* $6000-$67FF: A5    = mirroring (1=horizontal, 0=vertical)      */
  /*              A4-A3 = high two bits of 8K CHR bank              */
  /*              A2    = register 1 enable (0=disabled, 1=enabled) */
  /*              A2-A0 = 32K PRG bank                              */
  register_low = (uint8) (address & 0x3F);
  mmc_bankrom (32, 0x8000, register_low & 0x07);
  map41_set_chr ();
  if (register_low & 0x20) ppu_mirror(0, 0, 1, 1); /* horizontal */
  else                     ppu_mirror(0, 1, 0, 1); /* vertical */

  /* Done */
  return;
}

/******************************************/
/* Mapper #41 write handler ($8000-$FFFF) */
/******************************************/
static void map41_high_write (uint32 address, uint8 value)
{
  /* Address doesn't matter within this range */
  UNUSED (address);

  /* $8000-$FFFF: D1-D0 = low two bits of 8K CHR bank */
  if (register_low & 0x04)
  {
    register_high = value & 0x03;
    map41_set_chr ();
  }

  /* Done */
  return;
}

/****************************************************/
/* Shove extra mapper information into a SNSS block */
/****************************************************/
static void map41_setstate (SnssMapperBlock *state)
{
  /* TODO: Store SNSS information */
  UNUSED (state);

  /* Done */
  return;
}

/*****************************************************/
/* Pull extra mapper information out of a SNSS block */
/*****************************************************/
static void map41_getstate (SnssMapperBlock *state)
{
  /* TODO: Retrieve SNSS information */
  UNUSED (state);

  /* Done */
  return;
}

static const map_memwrite map41_memwrite [] =
{
   { 0x6000, 0x67FF, map41_low_write },
   { 0x8000, 0xFFFF, map41_high_write },
   {     -1,     -1, NULL }
};

const mapintf_t map41_intf =
{
   41,                               /* Mapper number */
   "Caltron 6 in 1",                 /* Mapper name */
   map41_init,                       /* Initialization routine */
   NULL,                             /* VBlank callback */
   NULL,                             /* HBlank callback */
   map41_getstate,                   /* Get state (SNSS) */
   map41_setstate,                   /* Set state (SNSS) */
   NULL,                             /* Memory read structure */
   map41_memwrite,                   /* Memory write structure */
   NULL                              /* External sound device */
};

/*
** $Log: map041.c,v $
** Revision 1.2  2001/04/27 14:37:11  neil
** wheeee
**
** Revision 1.1  2001/04/27 12:54:40  neil
** blah
**
** Revision 1.1  2001/04/27 10:57:41  neil
** wheee
**
** Revision 1.1  2000/12/30 00:33:15  firebug
** initial revision
**
**
*/
