/**************************************************************************/
/*
      libsnss.c

      (C) 2000 The SNSS Group
      See README.TXT file for license and terms of use.

      $Id: libsnss.c,v 1.2 2001/04/27 14:37:11 neil Exp $
*/
/**************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libsnss.h>

/**************************************************************************/
/* This section deals with endian-specific code. */
/**************************************************************************/

static unsigned int
swap32 (unsigned int source)
{
#ifdef USE_LITTLE_ENDIAN
   char buffer[4];

   buffer[0] = ((char *) &source)[3];
   buffer[1] = ((char *) &source)[2];
   buffer[2] = ((char *) &source)[1];
   buffer[3] = ((char *) &source)[0];

   return *((unsigned int *) buffer);
#else /* !USE_LITTLE_ENDIAN */
   return source;
#endif /* !USE_LITTLE_ENDIAN */
}

static unsigned short
swap16 (unsigned short source)
{
#ifdef USE_LITTLE_ENDIAN
   char buffer[2];

   buffer[0] = ((char *) &source)[1];
   buffer[1] = ((char *) &source)[0];

   return *((unsigned short *) buffer);
#else /* !USE_LITTLE_ENDIAN */
   return source;
#endif /* !USE_LITTLE_ENDIAN */
}

/**************************************************************************/
/* support functions */
/**************************************************************************/

#define MIN(a,b) (((a) < (b)) ? (a) : (b))

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadBlockHeader (SnssBlockHeader *header, SNSS_FILE *snssFile)
{
   char headerBytes[12];

   if (fread (headerBytes, 12, 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   strncpy (header->tag, &headerBytes[0], TAG_LENGTH);
   header->tag[4] = '\0';
   header->blockVersion = *((unsigned int *) &headerBytes[4]);
   header->blockVersion = swap32 (header->blockVersion);
   header->blockLength = *((unsigned int *) &headerBytes[8]);
   header->blockLength = swap32 (header->blockLength);

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteBlockHeader (SnssBlockHeader *header, SNSS_FILE *snssFile)
{
   char headerBytes[12];
   unsigned int tempInt;

   strncpy (&headerBytes[0], header->tag, TAG_LENGTH);

   tempInt = swap32 (header->blockVersion);
   headerBytes[4] = ((char *) &tempInt)[0];
   headerBytes[5] = ((char *) &tempInt)[1];
   headerBytes[6] = ((char *) &tempInt)[2];
   headerBytes[7] = ((char *) &tempInt)[3];

   tempInt = swap32 (header->blockLength);
   headerBytes[8] = ((char *) &tempInt)[0];
   headerBytes[9] = ((char *) &tempInt)[1];
   headerBytes[10] = ((char *) &tempInt)[2];
   headerBytes[11] = ((char *) &tempInt)[3];

   if (fwrite (headerBytes, 12, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   return SNSS_OK;
}

/**************************************************************************/

const char *
SNSS_GetErrorString (SNSS_RETURN_CODE code)
{
   switch (code)
   {
   case SNSS_OK:
      return "no error";

   case SNSS_BAD_FILE_TAG:
      return "not an SNSS file";

   case SNSS_OPEN_FAILED:
      return "could not open SNSS file";

   case SNSS_CLOSE_FAILED:
      return "could not close SNSS file";

   case SNSS_READ_FAILED:
      return "could not read from SNSS file";

   case SNSS_WRITE_FAILED:
      return "could not write to SNSS file";

   case SNSS_OUT_OF_MEMORY:
      return "out of memory";

   case SNSS_UNSUPPORTED_BLOCK:
      return "unsupported block type";

   default:
      return "unknown error";
   }
}

/**************************************************************************/
/* functions for reading and writing SNSS file headers */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadFileHeader (SNSS_FILE *snssFile)
{
   if (fread (snssFile->headerBlock.tag, 4, 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   if (0 != strncmp(snssFile->headerBlock.tag, "SNSS", 4))
   {
      return SNSS_BAD_FILE_TAG;
   }

   snssFile->headerBlock.tag[4] = '\0';

   if (fread (&snssFile->headerBlock.numberOfBlocks, sizeof (unsigned int), 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   snssFile->headerBlock.numberOfBlocks = swap32 (snssFile->headerBlock.numberOfBlocks);

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteFileHeader (SNSS_FILE *snssFile)
{
   unsigned int tempInt;
   char writeBuffer[8];

   /* always place the SNSS tag in this field */
   strncpy (&writeBuffer[0], "SNSS", 4);
   tempInt = swap32 (snssFile->headerBlock.numberOfBlocks);
   writeBuffer[4] = ((char *) &tempInt)[0];
   writeBuffer[5] = ((char *) &tempInt)[1];
   writeBuffer[6] = ((char *) &tempInt)[2];
   writeBuffer[7] = ((char *) &tempInt)[3];

   if (fwrite (writeBuffer, 8, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   return SNSS_OK;
}

/**************************************************************************/
/* general file manipulation functions */
/**************************************************************************/
SNSS_RETURN_CODE
SNSS_OpenFile (SNSS_FILE **snssFile, const char *filename, SNSS_OPEN_MODE mode)
{
   *snssFile = malloc(sizeof(SNSS_FILE));
   if (NULL == *snssFile)
   {
      return SNSS_OUT_OF_MEMORY;
   }

   /* zero the memory */
   memset (*snssFile, 0, sizeof(SNSS_FILE));

   (*snssFile)->mode = mode;

   if (SNSS_OPEN_READ == mode)
   {
      (*snssFile)->fp = fopen (filename, "rb");
   }
   else
   {
      (*snssFile)->fp = fopen (filename, "wb");
      (*snssFile)->headerBlock.numberOfBlocks = 0;
   }

   if (NULL == (*snssFile)->fp)
   {
      free(*snssFile);
      *snssFile = NULL;
      return SNSS_OPEN_FAILED;
   }

   if (SNSS_OPEN_READ == mode)
   {
      return SNSS_ReadFileHeader(*snssFile);
   }
   else
   {
      return SNSS_WriteFileHeader(*snssFile);
   }
}

/**************************************************************************/

SNSS_RETURN_CODE
SNSS_CloseFile (SNSS_FILE **snssFile)
{

   return SNSS_OK;
}

/**************************************************************************/

SNSS_RETURN_CODE
SNSS_GetNextBlockType (SNSS_BLOCK_TYPE *blockType, SNSS_FILE *snssFile)
{
  // REMOVED
   return SNSS_OK;
}

/**************************************************************************/

SNSS_RETURN_CODE
SNSS_SkipNextBlock (SNSS_FILE *snssFile)
{
  // REMOVED
   return SNSS_OK;
}

/**************************************************************************/
/* functions for reading and writing base register blocks */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadBaseBlock (SNSS_FILE *snssFile)
{
   char blockBytes[BASE_BLOCK_LENGTH];
   SnssBlockHeader header;

   if (SNSS_ReadBlockHeader (&header, snssFile) != SNSS_OK)
   {
      return SNSS_READ_FAILED;
   }

   if (fread (blockBytes, MIN (header.blockLength, BASE_BLOCK_LENGTH), 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   snssFile->baseBlock.regA = blockBytes[0x0];
   snssFile->baseBlock.regX = blockBytes[0x1];
   snssFile->baseBlock.regY = blockBytes[0x2];
   snssFile->baseBlock.regFlags = blockBytes[0x3];
   snssFile->baseBlock.regStack = blockBytes[0x4];
   snssFile->baseBlock.regPc = *((unsigned short *) &blockBytes[0x5]);
   snssFile->baseBlock.regPc = swap16 (snssFile->baseBlock.regPc);
   snssFile->baseBlock.reg2000 = blockBytes[0x7];
   snssFile->baseBlock.reg2001 = blockBytes[0x8];
   memcpy (&snssFile->baseBlock.cpuRam, &blockBytes[0x9], 0x800);
   memcpy (&snssFile->baseBlock.spriteRam, &blockBytes[0x809], 0x100);
   memcpy (&snssFile->baseBlock.ppuRam, &blockBytes[0x909], 0x1000);
   memcpy (&snssFile->baseBlock.palette, &blockBytes[0x1909], 0x20);
   memcpy (&snssFile->baseBlock.mirrorState, &blockBytes[0x1929], 0x4);
   snssFile->baseBlock.vramAddress = *((unsigned short *) &blockBytes[0x192D]);
   snssFile->baseBlock.vramAddress = swap16 (snssFile->baseBlock.vramAddress);
   snssFile->baseBlock.spriteRamAddress = blockBytes[0x192F];
   snssFile->baseBlock.tileXOffset = blockBytes[0x1930];

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteBaseBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;
   SNSS_RETURN_CODE returnCode;
   char blockBytes[BASE_BLOCK_LENGTH];
   unsigned short tempShort;

   strcpy (header.tag, "BASR");
   header.blockVersion = SNSS_BLOCK_VERSION;
   header.blockLength = BASE_BLOCK_LENGTH;

   if ((returnCode = SNSS_WriteBlockHeader (&header, snssFile)) != SNSS_OK)
   {
      return returnCode;
   }

   blockBytes[0x0] = snssFile->baseBlock.regA;
   blockBytes[0x1] = snssFile->baseBlock.regX;
   blockBytes[0x2] = snssFile->baseBlock.regY;
   blockBytes[0x3] = snssFile->baseBlock.regFlags;
   blockBytes[0x4] = snssFile->baseBlock.regStack;
   tempShort = swap16 (snssFile->baseBlock.regPc);
   blockBytes[0x5] = ((char *) &tempShort)[0];
   blockBytes[0x6] = ((char *) &tempShort)[1];
   blockBytes[0x7] = snssFile->baseBlock.reg2000;
   blockBytes[0x8] = snssFile->baseBlock.reg2001;
   memcpy (&blockBytes[0x9], &snssFile->baseBlock.cpuRam, 0x800);
   memcpy (&blockBytes[0x809], &snssFile->baseBlock.spriteRam, 0x100);
   memcpy (&blockBytes[0x909], &snssFile->baseBlock.ppuRam, 0x1000);
   memcpy (&blockBytes[0x1909], &snssFile->baseBlock.palette, 0x20);
   memcpy (&blockBytes[0x1929], &snssFile->baseBlock.mirrorState, 0x4);
   tempShort = swap16 (snssFile->baseBlock.vramAddress);
   blockBytes[0x192D] = ((char *) &tempShort)[0];
   blockBytes[0x192E] = ((char *) &tempShort)[1];
   blockBytes[0x192F] = snssFile->baseBlock.spriteRamAddress;
   blockBytes[0x1930] = snssFile->baseBlock.tileXOffset;

   if (fwrite (blockBytes, BASE_BLOCK_LENGTH, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   snssFile->headerBlock.numberOfBlocks++;

   return SNSS_OK;
}

/**************************************************************************/
/* functions for reading and writing VRAM blocks */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadVramBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;

   if (SNSS_ReadBlockHeader (&header, snssFile) != SNSS_OK)
   {
      return SNSS_READ_FAILED;
   }

   if (fread (snssFile->vramBlock.vram, MIN (header.blockLength, VRAM_16K), 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   snssFile->vramBlock.vramSize = header.blockLength;

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteVramBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;
   SNSS_RETURN_CODE returnCode;

   strcpy (header.tag, "VRAM");
   header.blockVersion = SNSS_BLOCK_VERSION;
   header.blockLength = snssFile->vramBlock.vramSize;

   if ((returnCode = SNSS_WriteBlockHeader (&header, snssFile)) != SNSS_OK)
   {
      return returnCode;
   }

   if (fwrite (snssFile->vramBlock.vram, snssFile->vramBlock.vramSize, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   snssFile->headerBlock.numberOfBlocks++;

   return SNSS_OK;
}

/**************************************************************************/
/* functions for reading and writing SRAM blocks */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadSramBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;

   if (SNSS_ReadBlockHeader (&header, snssFile) != SNSS_OK)
   {
      return SNSS_READ_FAILED;
   }

   if (fread (&snssFile->sramBlock.sramEnabled, 1, 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   /* read blockLength - 1 bytes to get all of the SRAM */
   if (fread (&snssFile->sramBlock.sram, MIN (header.blockLength - 1, SRAM_8K), 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   /* SRAM size is the size of the block - 1 (SRAM enabled byte) */
   snssFile->sramBlock.sramSize = header.blockLength - 1;

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteSramBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;
   SNSS_RETURN_CODE returnCode;

   strcpy (header.tag, "SRAM");
   header.blockVersion = SNSS_BLOCK_VERSION;
   /* length of block is size of SRAM plus SRAM enabled byte */
   header.blockLength = snssFile->sramBlock.sramSize + 1;
   if ((returnCode = SNSS_WriteBlockHeader (&header, snssFile)) != SNSS_OK)
   {
      return returnCode;
   }

   if (fwrite (&snssFile->sramBlock.sramEnabled, 1, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   if (fwrite (snssFile->sramBlock.sram, snssFile->sramBlock.sramSize, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   snssFile->headerBlock.numberOfBlocks++;

   return SNSS_OK;
}

/**************************************************************************/
/* functions for reading and writing mapper data blocks */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadMapperBlock (SNSS_FILE *snssFile)
{
   char *blockBytes;
   int i;
   SnssBlockHeader header;

   if (SNSS_ReadBlockHeader (&header, snssFile) != SNSS_OK)
   {
      return SNSS_READ_FAILED;
   }

   if ((blockBytes = (char *) malloc (0x8 + 0x10 + 0x80)) == NULL)
   {
      return SNSS_OUT_OF_MEMORY;
   }

   if (fread (blockBytes, MIN (0x8 + 0x10 + 0x80, header.blockLength), 1, snssFile->fp) != 1)
   {
      free(blockBytes);
      return SNSS_READ_FAILED;
   }

   for (i = 0; i < 4; i++)
   {
      snssFile->mapperBlock.prgPages[i] = *((unsigned short *) &blockBytes[i * 2]);
      snssFile->mapperBlock.prgPages[i] = swap16 (snssFile->mapperBlock.prgPages[i]);
   }

   for (i = 0; i < 8; i++)
   {
      snssFile->mapperBlock.chrPages[i] = *((unsigned short *) &blockBytes[0x8 + (i * 2)]);
      snssFile->mapperBlock.chrPages[i] = swap16 (snssFile->mapperBlock.chrPages[i]);
   }

   memcpy (&snssFile->mapperBlock.extraData.mapperData, &blockBytes[0x18], 0x80);

   free (blockBytes);

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteMapperBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;
   char blockBytes[MAPPER_BLOCK_LENGTH];
   unsigned short tempShort;
   int i;
   SNSS_RETURN_CODE returnCode;

   strcpy (header.tag, "MPRD");
   header.blockVersion = SNSS_BLOCK_VERSION;
   header.blockLength = MAPPER_BLOCK_LENGTH;

   if ((returnCode = SNSS_WriteBlockHeader (&header, snssFile)) != SNSS_OK)
   {
      return returnCode;
   }

   for (i = 0; i < 4; i++)
   {
      tempShort = swap16 (snssFile->mapperBlock.prgPages[i]);
      blockBytes[(i * 2) + 0] = ((char *) &tempShort)[0];
      blockBytes[(i * 2) + 1] = ((char *) &tempShort)[1];
   }

   for (i = 0; i < 8; i++)
   {
      tempShort = swap16 (snssFile->mapperBlock.chrPages[i]);
      blockBytes[0x8 + (i * 2) + 0] = ((char *) &tempShort)[0];
      blockBytes[0x8 + (i * 2) + 1] = ((char *) &tempShort)[1];
   }

   memcpy (&blockBytes[0x18], &snssFile->mapperBlock.extraData.mapperData, 0x80);

   if (fwrite (blockBytes, MAPPER_BLOCK_LENGTH, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   snssFile->headerBlock.numberOfBlocks++;

   return SNSS_OK;
}

/**************************************************************************/
/* functions for reading and writing controller data blocks */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadControllersBlock (SNSS_FILE *snssFile)
{
   /* quell warnings */
   snssFile = snssFile;

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteControllersBlock (SNSS_FILE *snssFile)
{
   /* quell warnings */
   snssFile = snssFile;

   return SNSS_OK;
}

/**************************************************************************/
/* functions for reading and writing sound blocks */
/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_ReadSoundBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;

   if (SNSS_ReadBlockHeader (&header, snssFile) != SNSS_OK)
   {
      return SNSS_READ_FAILED;
   }

   if (fread (snssFile->soundBlock.soundRegisters, MIN (header.blockLength, 0x16), 1, snssFile->fp) != 1)
   {
      return SNSS_READ_FAILED;
   }

   return SNSS_OK;
}

/**************************************************************************/

static SNSS_RETURN_CODE
SNSS_WriteSoundBlock (SNSS_FILE *snssFile)
{
   SnssBlockHeader header;
   SNSS_RETURN_CODE returnCode;

   strcpy (header.tag, "SOUN");
   header.blockVersion = SNSS_BLOCK_VERSION;
   header.blockLength = SOUND_BLOCK_LENGTH;

   if ((returnCode = SNSS_WriteBlockHeader (&header, snssFile)) != SNSS_OK)
   {
      return returnCode;
   }

   if (fwrite (snssFile->soundBlock.soundRegisters, SOUND_BLOCK_LENGTH, 1, snssFile->fp) != 1)
   {
      return SNSS_WRITE_FAILED;
   }

   snssFile->headerBlock.numberOfBlocks++;

   return SNSS_OK;
}

/**************************************************************************/
/* general functions for reading and writing SNSS data blocks */
/**************************************************************************/

SNSS_RETURN_CODE
SNSS_ReadBlock (SNSS_FILE *snssFile, SNSS_BLOCK_TYPE blockType)
{
   switch (blockType)
   {
   case SNSS_BASR:
      return SNSS_ReadBaseBlock (snssFile);

   case SNSS_VRAM:
      return SNSS_ReadVramBlock (snssFile);

   case SNSS_SRAM:
      return SNSS_ReadSramBlock (snssFile);

   case SNSS_MPRD:
      return SNSS_ReadMapperBlock (snssFile);

   case SNSS_CNTR:
      return SNSS_ReadControllersBlock (snssFile);

   case SNSS_SOUN:
      return SNSS_ReadSoundBlock (snssFile);

   case SNSS_UNKNOWN_BLOCK:
   default:
       return SNSS_UNSUPPORTED_BLOCK;
   }
}

/**************************************************************************/

SNSS_RETURN_CODE
SNSS_WriteBlock (SNSS_FILE *snssFile, SNSS_BLOCK_TYPE blockType)
{
   switch (blockType)
   {
   case SNSS_BASR:
      return SNSS_WriteBaseBlock (snssFile);

   case SNSS_VRAM:
      return SNSS_WriteVramBlock (snssFile);

   case SNSS_SRAM:
      return SNSS_WriteSramBlock (snssFile);

   case SNSS_MPRD:
      return SNSS_WriteMapperBlock (snssFile);

   case SNSS_CNTR:
      return SNSS_WriteControllersBlock (snssFile);

   case SNSS_SOUN:
      return SNSS_WriteSoundBlock (snssFile);

   case SNSS_UNKNOWN_BLOCK:
   default:
       return SNSS_UNSUPPORTED_BLOCK;
   }
}

/*
** $Log: libsnss.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 1.1.1.1  2001/04/27 07:03:54  neil
** initial
**
** Revision 1.1  2000/10/24 12:19:01  matt
** changed directory structure
**
** Revision 1.9  2000/10/10 13:03:54  matt
** Mr. Clean makes a guest appearance
**
** Revision 1.8  2000/08/16 02:58:34  matt
** random cleanups
**
** Revision 1.7  2000/07/17 01:52:27  matt
** made sure last line of all source files is a newline
**
** Revision 1.6  2000/07/10 01:54:16  matt
** state is now zeroed when it is allocated
**
** Revision 1.5  2000/07/09 15:37:21  matt
** all block read/write calls now pass through a common handler
**
** Revision 1.4  2000/07/09 03:39:06  matt
** minor modifications
**
** Revision 1.3  2000/07/08 16:01:39  matt
** added bald's changes, made error checking more robust
**
** Revision 1.2  2000/07/04 04:46:06  matt
** simplified handling of SNSS states
**
** Revision 1.1  2000/06/29 14:13:28  matt
** initial revision
**
*/