1  /*
  2  ** Nofrendo (c) 1998-2000 Matthew Conte (matt@conte.com)
  3  **
  4  **
  5  ** This program is free software; you can redistribute it and/or
  6  ** modify it under the terms of version 2 of the GNU Library General 
  7  ** Public License as published by the Free Software Foundation.
  8  **
  9  ** This program is distributed in the hope that it will be useful, 
 10  ** but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
 12  ** Library General Public License for more details.  To obtain a 
 13  ** copy of the GNU Library General Public License, write to the Free 
 14  ** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 15  **
 16  ** Any permitted reproduction of these routines, in whole or in part,
 17  ** must bear this legend.
 18  **
 19  **
 20  ** map046.c
 21  **
 22  ** Mapper #46 (Pelican Game Station)
 23  ** Implementation by Firebug
 24  ** Mapper information courtesy of Kevin Horton
 25  ** $Id: map046.c,v 1.2 2001/04/27 14:37:11 neil Exp $
 26  **
 27  */
 28  
 29  #include "noftypes.h"
 30  #include "nes_mmc.h"
 31  #include "nes.h"
 32  #include "libsnss.h"
 33  #include "log.h"
 34  
 35  static uint8 prg_low_bank;
 36  static uint8 chr_low_bank;
 37  static uint8 prg_high_bank;
 38  static uint8 chr_high_bank;
 39  
 40  /*************************************************/
 41  /* Set banks from the combined register values   */
 42  /*************************************************/
 43  static void map46_set_banks (void)
 44  {
 45    /* Set the PRG and CHR pages */
 46    mmc_bankrom (32, 0x8000, (prg_high_bank << 1) | (prg_low_bank));
 47    mmc_bankvrom (8, 0x0000, (chr_high_bank << 3) | (chr_low_bank));
 48  
 49    /* Done */
 50    return;
 51  }
 52  
 53  /*********************************************************/
 54  /* Mapper #46: Pelican Game Station (aka Rumble Station) */
 55  /*********************************************************/
 56  static void map46_init (void)
 57  {
 58    /* High bank switch register is set to zero on reset */
 59    prg_high_bank = 0x00;
 60    chr_high_bank = 0x00;
 61    map46_set_banks ();
 62  
 63    /* Done */
 64    return;
 65  }
 66  
 67  /******************************************/
 68  /* Mapper #46 write handler ($6000-$FFFF) */
 69  /******************************************/
 70  static void map46_write (uint32 address, uint8 value)
 71  {
 72    /* $8000-$FFFF: D6-D4 = lower three bits of CHR bank */
 73    /*              D0    = low bit of PRG bank          */
 74    /* $6000-$7FFF: D7-D4 = high four bits of CHR bank   */
 75    /*              D3-D0 = high four bits of PRG bank   */
 76    if (address & 0x8000)
 77    {
 78      prg_low_bank = value & 0x01;
 79      chr_low_bank = (value >> 4) & 0x07;
 80      map46_set_banks ();
 81    }
 82    else
 83    {
 84      prg_high_bank = value & 0x0F;
 85      chr_high_bank = (value >> 4) & 0x0F;
 86      map46_set_banks ();
 87    }
 88  
 89    /* Done */
 90    return;
 91  }
 92  
 93  /****************************************************/
 94  /* Shove extra mapper information into a SNSS block */
 95  /****************************************************/
 96  static void map46_setstate (SnssMapperBlock *state)
 97  {
 98    /* TODO: Store SNSS information */
 99    UNUSED (state);
100  
101    /* Done */
102    return;
103  }
104  
105  /*****************************************************/
106  /* Pull extra mapper information out of a SNSS block */
107  /*****************************************************/
108  static void map46_getstate (SnssMapperBlock *state)
109  {
110    /* TODO: Retrieve SNSS information */
111    UNUSED (state);
112  
113    /* Done */
114    return;
115  }
116  
117  static const map_memwrite map46_memwrite [] =
118  {
119     { 0x6000, 0xFFFF, map46_write },
120     {     -1,     -1, NULL }
121  };
122  
123  const mapintf_t map46_intf =
124  {
125     46,                               /* Mapper number */
126     "Pelican Game Station",           /* Mapper name */
127     map46_init,                       /* Initialization routine */
128     NULL,                             /* VBlank callback */
129     NULL,                             /* HBlank callback */
130     map46_getstate,                   /* Get state (SNSS) */
131     map46_setstate,                   /* Set state (SNSS) */
132     NULL,                             /* Memory read structure */
133     map46_memwrite,                   /* Memory write structure */
134     NULL                              /* External sound device */
135  };
136  
137  /*
138  ** $Log: map046.c,v $
139  ** Revision 1.2  2001/04/27 14:37:11  neil
140  ** wheeee
141  **
142  ** Revision 1.1  2001/04/27 12:54:40  neil
143  ** blah
144  **
145  ** Revision 1.1  2001/04/27 10:57:41  neil
146  ** wheee
147  **
148  ** Revision 1.1  2000/12/27 19:23:05  firebug
149  ** initial revision
150  **
151  **
152  */