/* cksum -- calculate and print POSIX.2 checksums and sizes of files
   Copyright (C) 92, 95, 1996 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by Q. Frank Xia, qx@math.columbia.edu.
   Cosmetic changes and reorganization by David MacKenzie, djm@gnu.ai.mit.edu.
  
   Modified on 10 OCT 1998  by Jim Lowe for inclusion in a library and to use 
   unix-like file descriptor object.  THESE CHANGES ARE UNRELATED TO THE FSF.
   Please obtain a pristine copy of this file if integrating with a new work.

  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:

      cc -DCRCTAB -o crctab cksum.c
      crctab > crctab.h

  As Bruce Evans pointed out to me, the crctab in the sample C code
  in 4.9.10 Rationale of P1003.2/D11.2 is represented in reversed order.
  Namely, 0x01 is represented as 0x80, 0x02 is represented as 0x40, etc.
  The generating polynomial is crctab[0x80]=0xedb88320 instead of
  crctab[1]=0x04C11DB7.  But the code works only for a non-reverse order
  crctab.  Therefore, the sample implementation is wrong.

  This software is compatible with neither the System V nor the BSD
  `sum' program.  It is supposed to conform to P1003.2/D11.2,
  except foreign language interface (4.9.5.3 of P1003.2/D11.2) support.
  Any inconsistency with the standard except 4.9.5.3 is a bug.  */

  /* Modified by jhl <jhlowe@acm.org> 29NOV99 for inclusion in swtools; 
   *  and, made the test crctab program write the chksum for testing purposes. 
   *     To make the test program: 
   *       if in the swtools tree, 
   *         cc -D CRCTAB  -I.. -I../../include cksum.c
   */

#define ROTATE_RIGHT(c) if ((c) & 01) (c) = ((c) >>1) + 0x8000; else (c) >>= 1;

#ifdef CRCTAB

#include "swuser_config.h"
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

unsigned long swlib_cksum (int uxfio_fd);
#define uxfio_read read

#define BIT(x)	( (unsigned long)1 << (x) )
#define SBIT	BIT(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));

static unsigned long r[8];

static void
fill_r ()
{
  int i;

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

static unsigned long
remainder (m)
     int m;
{
  unsigned long rem = 0;
  int i;

  for (i = 0; i < 8; i++)
    if (BIT (i) & m)
      rem = rem ^ r[i];

  return rem & 0xFFFFFFFF;	/* Make it run on 64-bit machine.  */
}

int
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");

  printf ("the cksum is %u\n", swlib_cksum(STDIN_FILENO));
  
  exit (EXIT_SUCCESS);
}

#endif /* !CRCTAB */

/* --------------------------------------------------------------------*/


#include <stdio.h>
#include <stdlib.h>
#ifndef CRCTAB
#include "uxfio.h"
#endif /* CRCTAB */
#include <sys/types.h>

/* Number of bytes to read at once.  */
#define BUFLEN (1 << 16)

static unsigned long const 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
};

/* Nonzero if any of the files read were the standard input. */

unsigned long
swlib_bsd_sum_from_mem(unsigned char * data, size_t len)
{
	unsigned long sum = 0;
	unsigned char * s;
	int count = 0;
	int ch;

	s = data;
	while (count < (int)len)
	{
		ch = (int)(*s);
		ROTATE_RIGHT (sum);
		sum += ch;
		sum &= 0xffff;
		count ++;
		s++;
	}
	return sum;
}

unsigned long
swlib_cksum (int uxfio_fd)
{
  unsigned char buf[BUFLEN];
  unsigned long crc = 0;
  long file_length = 0;
  long bytes_read;

  while ((bytes_read = uxfio_read (uxfio_fd, buf, BUFLEN)) > 0)
    {
      unsigned char *cp = buf;

      file_length += bytes_read;
      while (bytes_read--)
	crc = (crc << 8) ^ crctab[((crc >> 24) ^ *(cp++)) & 0xFF];
    }

  bytes_read = file_length;
  while (bytes_read > 0)
    {
      crc = (crc << 8) ^ crctab[((crc >> 24) ^ bytes_read) & 0xFF];
      bytes_read >>= 8;
    }

  crc = ~crc & 0xFFFFFFFF;
  return crc;
}

