/*

 Perl Extension for 32bit CRC computations

 by Soenke J. Peters

*/

#include "EXTERN.h"

#include "perl.h"

#include "XSUB.h"

/* 

 Based on CRC-32 version 1.04 by Craig Bruce, 05-Dec-1994

*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#ifdef GENTABLE

U32 

crcTable[256];

void

crcgen( void )

{

    U32 crc, poly;

    int     i, j;

    poly = 0xEDB88320L;

    for (i=0; i<256; i++) {

        crc = i;

        for (j=8; j>0; j--) {

            if (crc&1) {

                crc = (crc >> 1) ^ poly;

            } else {

                crc >>= 1;

            }

        }

        crcTable[i] = crc;

    }

}

#else /* GENTABLE */

U32

crcTable[256] = {

0x0, 0x77073096, 0xee0e612c, 0x990951ba, 0x76dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,

0xedb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x9b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,

0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,

0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,

0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,

0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,

0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,

0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,

0x76dc4190, 0x1db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x6b6b51f, 0x9fbfe4a5, 0xe8b8d433,

0x7807c9a2, 0xf00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x86d3d2d, 0x91646c97, 0xe6635c01,

0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,

0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,

0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,

0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,

0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,

0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,

0xedb88320, 0x9abfb3b6, 0x3b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x4db2615, 0x73dc1683,

0xe3630b12, 0x94643b84, 0xd6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0xa00ae27, 0x7d079eb1,

0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,

0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,

0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,

0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,

0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,

0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,

0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x26d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x5005713,

0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0xcb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0xbdbdf21,

0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,

0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,

0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,

0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,

0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,

0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,

};

#endif /* GENTABLE */

U32 

getcrc(char *c, int len, U32 crcinit)

{

    register U32 crc;

    char     *e = c + len;

    crc = crcinit^0xFFFFFFFF;

    while (c < e) {

        crc = ((crc >> 8) & 0x00FFFFFF) ^ crcTable[ (crc^ *c) & 0xFF ];

        ++c;

    }

    return( crc^0xFFFFFFFF );

}

#define BUFSIZE 32768

U32

getcrc_fp( PerlIO *fp, U32 crcinit )

{

    register U32 crc;

    register U16 len;

    unsigned char buf[BUFSIZE];

    crc = crcinit^0xFFFFFFFF;

    while((len = PerlIO_read(fp, buf, BUFSIZE)) > 0 ) {

        unsigned char * p = buf;

        do {

	    crc = ((crc >> 8) & 0x00FFFFFF) ^ crcTable[(unsigned char)( (crc & 0xff) ^ *(p++) )];

	} while (--len);

    }

    return( crc^0xFFFFFFFF );

}

svtype

getsvtype(SV *sv)

{

  if (sv == NULL )

    return SVt_NULL;

  if (SvROK(sv))

    return SvTYPE(SvRV(sv));

  else 

    return SvTYPE(sv);

}

MODULE = String::CRC32		PACKAGE = String::CRC32

VERSIONCHECK: DISABLE

PROTOTYPES: DISABLE 

U32

crc32(data, ...)

    char *data = NO_INIT

    PREINIT:

	U32 crcinit = 0;

    STRLEN data_len;

    PPCODE:

	int sv_type;

	IO *io;

	SV *sv;

	U32 rv = 0;

      {

#ifdef GENTABLE

	crcgen();

#endif /* GENTABLE */

	/* Horst Fickenscher <horst_fickenscher@sepp.de> mailed me that it

	   could be useful to supply an initial value other than 0, e.g.

	   to calculate checksums of big files without the need of keeping

	   them comletely in memory */

	if ( items > 1 )

		crcinit = (U32) SvNV(ST(items - 1));

	sv_type = getsvtype(ST(0));

	if (sv_type == SVt_PVGV)

	  {

		io = sv_2io(ST(0));

		rv = getcrc_fp(IoIFP(io), crcinit);

	  }

	else

	  {

		data = (char *)SvPV(ST(0),data_len);

		rv = getcrc(data, data_len, crcinit);

	  }

	EXTEND(sp, 1);

	sv = newSV(0);

	sv_setuv(sv, (UV)rv);

	PUSHs(sv_2mortal(sv));

      }