/* sum -- checksum and count the blocks in a file
   Copyright (C) 86, 89, 91, 1995-1999 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.  */

/* Like BSD sum or SysV sum -r, except like SysV sum if -s option is given. */

/* Written by Kayvan Aghaiepour and David MacKenzie. */

/* Optimized for fchksum by Matthew Mueller */

#include "fchksum.h"

#include <sys/types.h>
#include <unistd.h>

#define AUTHORS "Kayvan Aghaiepour and David MacKenzie"

/* Right-rotate 32-bit integer variable C. */
#define ROTATE_RIGHT(c) if ((c) & 01) (c) = ((c) >>1) + 0x8000; else (c) >>= 1;

/* Calculate and print the rotated checksum and the size in 1K blocks
   of file FILE, or of the standard input if FILE is "-".
   If PRINT_NAME is >1, print FILE next to the checksum and size.
   The checksum varies depending on sizeof(int).
   Return 0 if successful, -1 if an error occurs. */

int
bsd_sum_stream (int fd, unsigned long *res, chksum_size_t *size, CallbackInfo *cbinfo)
{
  unsigned char buf[FCHKSUMBLOCKSIZE];
  int bytes_read;
  unsigned long checksum = 0; /* The checksum mod 2^16. */

  chksum_size_reset(*size);
  while ((bytes_read = read (fd, buf, sizeof buf)) > 0)
    {
      register int i;

      for (i = 0; i < bytes_read; i++)
        {
          ROTATE_RIGHT (checksum);
	  checksum += buf[i];
	  checksum &= 0xffff;	/* Keep it within bounds. */
	}
      chksum_size_add(*size, bytes_read);
      if (do_callback(cbinfo, *size))
	return CHKSUM_EXCEPT;
    }

  if (bytes_read < 0)
    return CHKSUM_FERROR;
  
  *res = checksum;

  return CHKSUM_OK;
}

/* Calculate and print the checksum and the size in 512-byte blocks
   of file FILE, or of the standard input if FILE is "-".
   If PRINT_NAME is >0, print FILE next to the checksum and size.
   Return 0 if successful, -1 if an error occurs. */

int
sysv_sum_stream (int fd, unsigned long *res, chksum_size_t *size, CallbackInfo *cbinfo)
{
  unsigned char buf[FCHKSUMBLOCKSIZE];
  int bytes_read;
  unsigned long checksum = 0;

  chksum_size_reset(*size);
  while ((bytes_read = read (fd, buf, sizeof buf)) > 0)
    {
      register int i;

      for (i = 0; i < bytes_read; i++)
	checksum += buf[i];
      chksum_size_add(*size, bytes_read);
      if (do_callback(cbinfo, *size))
	return CHKSUM_EXCEPT;
    }

  if (bytes_read < 0)
    return CHKSUM_FERROR;

  *res = checksum % 0xffff;

  return CHKSUM_OK;
}