Genesis-Plus-GX/source/ngc/unzip.c

/******************************************************************************
 *
 * Nintendo Gamecube Zip Support
 *
 * Only partial support is included, in that only the first file within the archive
 * is considered to be a ROM image.
 ***************************************************************************/
#include "shared.h"
#include "dvd.h"
#include "font.h"
#include <zlib.h>

/* SDCARD File access */
extern FILE *sdfile;

/*
 * PKWare Zip Header - adopted into zip standard
 */
#define PKZIPID 0x504b0304
#define MAXROM 0x500000
#define ZIPCHUNK 2048

/*
 * Zip file header definition
 */
typedef struct
{
  unsigned int zipid __attribute__ ((__packed__));	// 0x04034b50
  unsigned short zipversion __attribute__ ((__packed__));
  unsigned short zipflags __attribute__ ((__packed__));
  unsigned short compressionMethod __attribute__ ((__packed__));
  unsigned short lastmodtime __attribute__ ((__packed__));
  unsigned short lastmoddate __attribute__ ((__packed__));
  unsigned int crc32 __attribute__ ((__packed__));
  unsigned int compressedSize __attribute__ ((__packed__));
  unsigned int uncompressedSize __attribute__ ((__packed__));
  unsigned short filenameLength __attribute__ ((__packed__));
  unsigned short extraDataLength __attribute__ ((__packed__));
} PKZIPHEADER;

/*
 * Zip files are stored little endian
 * Support functions for short and int types
 */
static inline u32 FLIP32 (u32 b)
{
  unsigned int c;
  c = (b & 0xff000000) >> 24;
  c |= (b & 0xff0000) >> 8;
  c |= (b & 0xff00) << 8;
  c |= (b & 0xff) << 24;
  return c;
}

static inline u16 FLIP16 (u16 b)
{
  u16 c;
  c = (b & 0xff00) >> 8;
  c |= (b & 0xff) << 8;
  return c;
}

/****************************************************************************
 * IsZipFile
 *
 * Returns TRUE when PKZIPID is first four characters of buffer
 ****************************************************************************/
int IsZipFile (char *buffer)
{
  unsigned int *check;
  check = (unsigned int *) buffer;
  if (check[0] == PKZIPID) return 1;
  return 0;
}

 /*****************************************************************************
 * UnZipBuffer
 *
 * It should be noted that there is a limit of 5MB total size for any ROM
 ******************************************************************************/
int UnZipBuffer (unsigned char *outbuffer, u64 discoffset, int length, u8 UseSDCARD)
{
  PKZIPHEADER pkzip;
  int zipoffset = 0;
  int zipchunk = 0;
  char out[ZIPCHUNK];
  z_stream zs;
  int res;
  int bufferoffset = 0;
  int have = 0;
  char readbuffer[2048];
  char msg[128];

  /*** Read Zip Header ***/
  if ( UseSDCARD )
  {
    fseek(sdfile, 0, SEEK_SET);
    fread(readbuffer, 1, 2048, sdfile);
  }
  else
  {
    dvd_read (&readbuffer, 2048, discoffset);
  }

  /*** Copy PKZip header to local, used as info ***/
  memcpy (&pkzip, &readbuffer, sizeof (PKZIPHEADER));

  sprintf (msg, "Unzipping %d bytes ... Wait", FLIP32 (pkzip.uncompressedSize));
  ShowAction (msg);

  /*** Prepare the zip stream ***/
  memset (&zs, 0, sizeof (z_stream));
  zs.zalloc = Z_NULL;
  zs.zfree = Z_NULL;
  zs.opaque = Z_NULL;
  zs.avail_in = 0;
  zs.next_in = Z_NULL;
  res = inflateInit2 (&zs, -MAX_WBITS);

  if (res != Z_OK) return 0;

  /*** Set ZipChunk for first pass ***/
  zipoffset = (sizeof (PKZIPHEADER) + FLIP16 (pkzip.filenameLength) + FLIP16 (pkzip.extraDataLength));
  zipchunk = ZIPCHUNK - zipoffset;

  /*** Now do it! ***/
  do
  {
    zs.avail_in = zipchunk;
    zs.next_in = (Bytef *) & readbuffer[zipoffset];
    
    /*** Now inflate until input buffer is exhausted ***/
    do
	  {
	    zs.avail_out = ZIPCHUNK;
	    zs.next_out = (Bytef *) & out;
 	    res = inflate (&zs, Z_NO_FLUSH);

	    if (res == Z_MEM_ERROR)
	    {
	      inflateEnd (&zs);
	      return 0;
	    }

	    have = ZIPCHUNK - zs.avail_out;
	    if (have)
	    {
        /*** Copy to normal block buffer ***/
	      memcpy (&outbuffer[bufferoffset], &out, have);
	      bufferoffset += have;
	    }
    }
    while (zs.avail_out == 0);

	  /*** Readup the next 2k block ***/
    zipoffset = 0;
    zipchunk = ZIPCHUNK;
	  
    if (UseSDCARD)
    {
      fread(readbuffer, 1, 2048, sdfile);
    }
    else
    {
      discoffset += 2048;
      dvd_read (&readbuffer, 2048, discoffset);
    }
  }
  while (res != Z_STREAM_END);

  inflateEnd (&zs);

  if (res == Z_STREAM_END)
  {
    if (FLIP32 (pkzip.uncompressedSize) == (u32) bufferoffset) return bufferoffset;
    else return FLIP32 (pkzip.uncompressedSize);
  }

  return 0;
}