/*
 * cksum   --- Calculate file checksums and sizes  (version 0.9)
 *       
 *     A POSIX (P1003,2/D11.2, 4.9) conformed utility
 *     written by Q. Frank Xia.
 */

/**************************************************************************
 * (C) Copyright Q. Frank Xia, Oct. 1992.  All rights reserved.           *
 *                                                                        *
 * Permission to use and redistribute this software is hereby granted     *
 * provided that the following conditions are met:                        *
 * 1. Source code redistribution must retain this statement.              *
 * 2. Binary redistribution must reproduce this statement in the          *
 *    documentation provided with the distribution.                       *
 * 3. This software is provided by author Q. Frank Xia "as is". There     *
 *    are absolutely no warranties at all. The author is not responsible  *
 *    for any possible damages caused by using this software.             *
 **************************************************************************/

/*
 * To compile this program, do
 *
 *     gcc -O -o cksum cksum.c
 *
 * Usage:
 * 
 *	cksum [file ...]
 *
 * The code segment between "#ifdef CRCTAB" and "#else" is the code 
 * which calculates the "crctab". It is included for those who want 
 * verify the correctness of the "crctab". To recreate the "crctab", 
 * do following:
 *
 *     gcc -O -DCRCTAB -o crctab cksum.c
 *     crctab > crctab.h
 *
 * I'd like to point out that the crctab in the sample C-code in 4.9.10
 * Rationale of P1003.2/D11.2 is not consistent with the Generating 
 * Polynomial defined in 4.9.2 of P1003.2/D11.2. In fact, the crctab 
 * given there is a dummy one.
 *
 * This software is neither compatible with System V nor BSD "sum" program.  
 * It is supposed to be conformed to P1003.2/D11.2 except foreign language
 * interface (4.9.5.3 of P1003.2/D11.2) support. Any single inconsistency 
 * with the standard except (4.9.5.3) is a bug. Please send bug report to
 *
 *     qx@math.columbia.edu
 *
 * -Q. Frank Xia, Oct. 1992.
 */

#ifdef CRCTAB

#include <stdio.h>

#define BIT(x)	( (unsigned long)1 << (x) )
#define LBIT	( (unsigned long)1 << 31 )

/*
 * The generating polynomial is 
 *
 *         32   26   23   22   16   12   11   10   8   7   5   4   2   1
 *   G(X)=X  + X  + X  + X  + X  + X  + X  + X  + X + X + X + X + X + X + 1
 *
 * The i bit in GEN is set if X^i is a summand of G(X) except X^32.
 */
#define GEN     (BIT(26)|BIT(23)|BIT(22)|BIT(16)|BIT(12)|BIT(11)|BIT(10)\
                |BIT(8) |BIT(7) |BIT(5) |BIT(4) |BIT(2) |BIT(1) |BIT(0));

unsigned long r[8];

void fill_r()
{
  int i;

  r[0]=GEN;
  for (i=1; i < 8; i++)
    r[i] = (r[i-1] & LBIT) ? (r[i-1] << 1) ^ r[0] : r[i-1] << 1;
}

unsigned int remainder(int m)
{
  unsigned long rem;
  int i;
 
  rem=0;
  for (i=0; i < 8; i++)
    if ( BIT(i) & m ) rem=rem ^ r[i];
 
  return rem;
}
 
void main()
{
  int i;
 
  fill_r();
  printf("unsigned long crctab[256] = {\n  0x0");
  for (i=0; i < 51; i++) {
    printf(",\n  0x%08X, 0x%08X, 0x%08X, 0x%08X, 0x%08X",
              remainder(i*5+1), remainder(i*5+2), remainder(i*5+3), 
              remainder(i*5+4), remainder(i*5+5));
  } 
  printf("\n};\n");
  exit(0);
}

#else /* CRCTAB.C */

#include <stdio.h>

#define BUFLEN	(1 << 13)
#define VERSION	"version 0.9"

unsigned long crctab[256] = {
  0x0,
  0x04C11DB7, 0x09823B6E, 0x0D4326D9, 0x130476DC, 0x17C56B6B,
  0x1A864DB2, 0x1E475005, 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6,
  0x2B4BCB61, 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD,
  0x4C11DB70, 0x48D0C6C7, 0x4593E01E, 0x4152FDA9, 0x5F15ADAC,
  0x5BD4B01B, 0x569796C2, 0x52568B75, 0x6A1936C8, 0x6ED82B7F,
  0x639B0DA6, 0x675A1011, 0x791D4014, 0x7DDC5DA3, 0x709F7B7A,
  0x745E66CD, 0x9823B6E0, 0x9CE2AB57, 0x91A18D8E, 0x95609039,
  0x8B27C03C, 0x8FE6DD8B, 0x82A5FB52, 0x8664E6E5, 0xBE2B5B58,
  0xBAEA46EF, 0xB7A96036, 0xB3687D81, 0xAD2F2D84, 0xA9EE3033,
  0xA4AD16EA, 0xA06C0B5D, 0xD4326D90, 0xD0F37027, 0xDDB056FE,
  0xD9714B49, 0xC7361B4C, 0xC3F706FB, 0xCEB42022, 0xCA753D95,
  0xF23A8028, 0xF6FB9D9F, 0xFBB8BB46, 0xFF79A6F1, 0xE13EF6F4,
  0xE5FFEB43, 0xE8BCCD9A, 0xEC7DD02D, 0x34867077, 0x30476DC0,
  0x3D044B19, 0x39C556AE, 0x278206AB, 0x23431B1C, 0x2E003DC5,
  0x2AC12072, 0x128E9DCF, 0x164F8078, 0x1B0CA6A1, 0x1FCDBB16,
  0x018AEB13, 0x054BF6A4, 0x0808D07D, 0x0CC9CDCA, 0x7897AB07,
  0x7C56B6B0, 0x71159069, 0x75D48DDE, 0x6B93DDDB, 0x6F52C06C,
  0x6211E6B5, 0x66D0FB02, 0x5E9F46BF, 0x5A5E5B08, 0x571D7DD1,
  0x53DC6066, 0x4D9B3063, 0x495A2DD4, 0x44190B0D, 0x40D816BA,
  0xACA5C697, 0xA864DB20, 0xA527FDF9, 0xA1E6E04E, 0xBFA1B04B,
  0xBB60ADFC, 0xB6238B25, 0xB2E29692, 0x8AAD2B2F, 0x8E6C3698,
  0x832F1041, 0x87EE0DF6, 0x99A95DF3, 0x9D684044, 0x902B669D,
  0x94EA7B2A, 0xE0B41DE7, 0xE4750050, 0xE9362689, 0xEDF73B3E,
  0xF3B06B3B, 0xF771768C, 0xFA325055, 0xFEF34DE2, 0xC6BCF05F,
  0xC27DEDE8, 0xCF3ECB31, 0xCBFFD686, 0xD5B88683, 0xD1799B34,
  0xDC3ABDED, 0xD8FBA05A, 0x690CE0EE, 0x6DCDFD59, 0x608EDB80,
  0x644FC637, 0x7A089632, 0x7EC98B85, 0x738AAD5C, 0x774BB0EB,
  0x4F040D56, 0x4BC510E1, 0x46863638, 0x42472B8F, 0x5C007B8A,
  0x58C1663D, 0x558240E4, 0x51435D53, 0x251D3B9E, 0x21DC2629,
  0x2C9F00F0, 0x285E1D47, 0x36194D42, 0x32D850F5, 0x3F9B762C,
  0x3B5A6B9B, 0x0315D626, 0x07D4CB91, 0x0A97ED48, 0x0E56F0FF,
  0x1011A0FA, 0x14D0BD4D, 0x19939B94, 0x1D528623, 0xF12F560E,
  0xF5EE4BB9, 0xF8AD6D60, 0xFC6C70D7, 0xE22B20D2, 0xE6EA3D65,
  0xEBA91BBC, 0xEF68060B, 0xD727BBB6, 0xD3E6A601, 0xDEA580D8,
  0xDA649D6F, 0xC423CD6A, 0xC0E2D0DD, 0xCDA1F604, 0xC960EBB3,
  0xBD3E8D7E, 0xB9FF90C9, 0xB4BCB610, 0xB07DABA7, 0xAE3AFBA2,
  0xAAFBE615, 0xA7B8C0CC, 0xA379DD7B, 0x9B3660C6, 0x9FF77D71,
  0x92B45BA8, 0x9675461F, 0x8832161A, 0x8CF30BAD, 0x81B02D74,
  0x857130C3, 0x5D8A9099, 0x594B8D2E, 0x5408ABF7, 0x50C9B640,
  0x4E8EE645, 0x4A4FFBF2, 0x470CDD2B, 0x43CDC09C, 0x7B827D21,
  0x7F436096, 0x7200464F, 0x76C15BF8, 0x68860BFD, 0x6C47164A,
  0x61043093, 0x65C52D24, 0x119B4BE9, 0x155A565E, 0x18197087,
  0x1CD86D30, 0x029F3D35, 0x065E2082, 0x0B1D065B, 0x0FDC1BEC,
  0x3793A651, 0x3352BBE6, 0x3E119D3F, 0x3AD08088, 0x2497D08D,
  0x2056CD3A, 0x2D15EBE3, 0x29D4F654, 0xC5A92679, 0xC1683BCE,
  0xCC2B1D17, 0xC8EA00A0, 0xD6AD50A5, 0xD26C4D12, 0xDF2F6BCB,
  0xDBEE767C, 0xE3A1CBC1, 0xE760D676, 0xEA23F0AF, 0xEEE2ED18,
  0xF0A5BD1D, 0xF464A0AA, 0xF9278673, 0xFDE69BC4, 0x89B8FD09,
  0x8D79E0BE, 0x803AC667, 0x84FBDBD0, 0x9ABC8BD5, 0x9E7D9662,
  0x933EB0BB, 0x97FFAD0C, 0xAFB010B1, 0xAB710D06, 0xA6322BDF,
  0xA2F33668, 0xBCB4666D, 0xB8757BDA, 0xB5365D03, 0xB1F740B4
};

char *pgm, *buf;

unsigned long cksum(FILE *inf, long *len)
{
  unsigned long crc = 0;
  long count, length = 0;
  int i, notdone = 1;

  while (notdone) {
    count=fread(buf, 1, BUFLEN, inf);
    for (i = 0; i < count; i++)
      crc = (crc << 8) ^ crctab[(crc >> 24) ^ buf[i]];
    length += count;
    if ( count < BUFLEN) {
      if ( ferror(inf) ) {
	*len = -1;
	return ~crc;
      }
      notdone = 0;
    }
  }
  *len = length;
  while ( length ) {
    crc = (crc << 8) ^ crctab[(crc >> 24) ^ (length & 0xFF)];
    length >>= 8;
  }

  return ~crc;
}

void main(int argc, char **argv)
{
  unsigned long crc;
  FILE *infile;
  char *fp;
  int error=0;
  long size;

  if ( argc > 1 && *(argv[1]) == '-') {
    fprintf(stderr, 
            "cksum (%s) by Q. Frank Xia.\nusage: cksum [file ...]\n", VERSION);
    exit(1);
  }
  pgm=argv[0];
  buf = (char *) malloc(BUFLEN);
  if (!buf) {
    fprintf(stderr, "%s: allocate memory error\n", pgm);
    exit(1);
  }

  if (argc==1) {
    crc=cksum(stdin, &size);
    printf("%10u %8d\n", crc, size);
    exit(0);
  }
  
  while (--argc > 0) {
    infile=fopen(*(++argv), "rb");
    if (!infile) {
      error=1;
      fprintf(stderr, "%s: open file \'%s\' error\n", pgm, *argv);
    }
    else {
      crc=cksum(infile, &size);
      if (size < 0) {
	error=1;
	fprintf(stderr, "%s; read file \'%s\' error\n", pgm, *argv);
      }
      else {
	printf("%10u %8d  %s\n", crc, size, *argv);
	fclose(infile);
      }
    }
  }

  if (error)
    exit(1);

  exit(0);
}

#endif /* CRCTAB.C */