git.sur5r.net Git - cc65/blob - src/sim65/chips/ram.c

   1 /*****************************************************************************/
   2 /*                                                                           */
   3 /*                                   ram.c                                   */
   4 /*                                                                           */
   5 /*                  RAM plugin for the sim65 6502 simulator                  */
   6 /*                                                                           */
   7 /*                                                                           */
   8 /*                                                                           */
   9 /* (C) 2002      Ullrich von Bassewitz                                       */
  10 /*               Wacholderweg 14                                             */
  11 /*               D-70597 Stuttgart                                           */
  12 /* EMail:        uz@musoftware.de                                            */
  13 /*                                                                           */
  14 /*                                                                           */
  15 /* This software is provided 'as-is', without any expressed or implied       */
  16 /* warranty.  In no event will the authors be held liable for any damages    */
  17 /* arising from the use of this software.                                    */
  18 /*                                                                           */
  19 /* Permission is granted to anyone to use this software for any purpose,     */
  20 /* including commercial applications, and to alter it and redistribute it    */
  21 /* freely, subject to the following restrictions:                            */
  22 /*                                                                           */
  23 /* 1. The origin of this software must not be misrepresented; you must not   */
  24 /*    claim that you wrote the original software. If you use this software   */
  25 /*    in a product, an acknowledgment in the product documentation would be  */
  26 /*    appreciated but is not required.                                       */
  27 /* 2. Altered source versions must be plainly marked as such, and must not   */
  28 /*    be misrepresented as being the original software.                      */
  29 /* 3. This notice may not be removed or altered from any source              */
  30 /*    distribution.                                                          */
  31 /*                                                                           */
  32 /*****************************************************************************/
  33
  34
  35
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 /* sim65 */
  40 #include "chipif.h"
  41
  42
  43
  44 /*****************************************************************************/
  45 /*                                   Forwards                                */
  46 /*****************************************************************************/
  47
  48
  49
  50 int InitChip (const struct SimData* Data);
  51 /* Initialize the chip, return an error code */
  52
  53 static void* InitInstance (unsigned Addr, unsigned Range);
  54 /* Initialize a new chip instance */
  55
  56 static void WriteCtrl (void* Data, unsigned Offs, unsigned char Val);
  57 /* Write control data */
  58
  59 static void Write (void* Data, unsigned Offs, unsigned char Val);
  60 /* Write user data */
  61
  62 static unsigned char ReadCtrl (void* Data, unsigned Offs);
  63 /* Read control data */
  64
  65 static unsigned char Read (void* Data, unsigned Offs);
  66 /* Read user data */
  67
  68
  69
  70 /*****************************************************************************/
  71 /*                                     Data                                  */
  72 /*****************************************************************************/
  73
  74
  75
  76 /* Control data passed to the main program */
  77 static const struct ChipData RAMData[1] = {
  78     {
  79         "RAM",                  /* Name of the chip */
  80         CHIPDATA_VER_MAJOR,     /* Version information */
  81         CHIPDATA_VER_MINOR,
  82
  83         /* -- Exported functions -- */
  84         InitChip,
  85         InitInstance,
  86         WriteCtrl,
  87         Write,
  88         ReadCtrl,
  89         Read
  90     }
  91 };
  92
  93 /* The SimData pointer we get when InitChip is called */
  94 static const SimData* Sim;
  95
  96 /* Possible RAM attributes */
  97 #define ATTR_INITIALIZED        0x01    /* RAM cell is intialized */
  98 #define ATTR_WPROT              0x02    /* RAM cell is write protected */
  99
 100 /* Data for one RAM instance */
 101 typedef struct InstanceData InstanceData;
 102 struct InstanceData {
 103     unsigned            BaseAddr;       /* Base address */
 104     unsigned            Range;          /* Memory range */
 105     unsigned char*      MemAttr;        /* Memory attributes */
 106     unsigned char*      Mem;            /* The memory itself */
 107 };
 108
 109
 110
 111 /*****************************************************************************/
 112 /*                               Exported function                           */
 113 /*****************************************************************************/
 114
 115
 116
 117 int GetChipData (const ChipData** Data, unsigned* Count)
 118 {
 119     /* Pass the control structure to the caller */
 120     *Data = RAMData;
 121     *Count = sizeof (Data) / sizeof (Data[0]);
 122
 123     /* Call was successful */
 124     return 0;
 125 }
 126
 127
 128
 129 /*****************************************************************************/
 130 /*                                     Code                                  */
 131 /*****************************************************************************/
 132
 133
 134
 135 int InitChip (const struct SimData* Data)
 136 /* Initialize the chip, return an error code */
 137 {
 138     /* Remember the pointer */
 139     Sim = Data;
 140
 141     /* Always successful */
 142     return 0;
 143 }
 144
 145
 146
 147 static void* InitInstance (unsigned Addr, unsigned Range)
 148 /* Initialize a new chip instance */
 149 {
 150     /* Allocate a new instance structure */
 151     InstanceData* D = Sim->Malloc (sizeof (InstanceData));
 152
 153     /* Initialize the structure, allocate RAM and attribute memory */
 154     D->BaseAddr = Addr;
 155     D->Range    = Range;
 156     D->MemAttr  = Sim->Malloc (Range * sizeof (D->MemAttr[0]));
 157     D->Mem      = Sim->Malloc (Range * sizeof (D->Mem[0]));
 158
 159     /* Clear the RAM and attribute memory */
 160     memset (D->MemAttr, 0, Range * sizeof (D->MemAttr[0]));
 161     memset (D->Mem, 0, Range * sizeof (D->Mem[0]));
 162
 163     /* Done, return the instance data */
 164     return D;
 165 }
 166
 167
 168
 169 static void WriteCtrl (void* Data, unsigned Offs, unsigned char Val)
 170 /* Write control data */
 171 {
 172     /* Cast the data pointer */
 173     InstanceData* D = (InstanceData*) Data;
 174
 175     /* Do the write and remember the cell as initialized */
 176     D->Mem[Offs] = Val;
 177     D->MemAttr[Offs] |= ATTR_INITIALIZED;
 178 }
 179
 180
 181
 182 static void Write (void* Data, unsigned Offs, unsigned char Val)
 183 /* Write user data */
 184 {
 185     /* Cast the data pointer */
 186     InstanceData* D = (InstanceData*) Data;
 187
 188     /* Check for a write to a write protected cell */
 189     if (D->MemAttr[Offs] & ATTR_WPROT) {
 190         Sim->Warning ("Writing to write protected memory at $%04X", D->BaseAddr+Offs);
 191     }
 192
 193     /* Do the write and remember the cell as initialized */
 194     D->Mem[Offs] = Val;
 195     D->MemAttr[Offs] |= ATTR_INITIALIZED;
 196 }
 197
 198
 199
 200 static unsigned char ReadCtrl (void* Data, unsigned Offs)
 201 /* Read control data */
 202 {
 203     /* Cast the data pointer */
 204     InstanceData* D = (InstanceData*) Data;
 205
 206     /* Read the cell and return the value */
 207     return D->Mem[Offs];
 208 }
 209
 210
 211
 212 static unsigned char Read (void* Data, unsigned Offs)
 213 /* Read user data */
 214 {
 215     /* Cast the data pointer */
 216     InstanceData* D = (InstanceData*) Data;
 217
 218     /* Check for a read from an uninitialized cell */
 219     if ((D->MemAttr[Offs] & ATTR_INITIALIZED) == 0) {
 220         /* We're reading a memory cell that was never written to */
 221         Sim->Warning ("Reading from uninitialized memory at $%04X", D->BaseAddr+Offs);
 222     }
 223
 224     /* Read the cell and return the value */
 225     return D->Mem[Offs];
 226 }
 227
 228
 229
 230