xref: /src/external/lgpl3/gmp/dist/mpz/out_raw.c

/* mpz_out_raw -- write an mpz_t in raw format.

Copyright 2001, 2002 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MP Library 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */

#include <stdio.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"


/* HTON_LIMB_STORE takes a normal host byte order limb and stores it as
   network byte order (ie. big endian). */

#if HAVE_LIMB_BIG_ENDIAN
#define HTON_LIMB_STORE(dst, limb)  do { *(dst) = (limb); } while (0)
#endif

#if HAVE_LIMB_LITTLE_ENDIAN
#define HTON_LIMB_STORE(dst, limb)  BSWAP_LIMB_STORE (dst, limb)
#endif

#ifndef HTON_LIMB_STORE
#define HTON_LIMB_STORE(dst, limb)                                      \
  do {                                                                  \
    mp_limb_t  __limb = (limb);                                         \
    char      *__p = (char *) (dst);                                    \
    int        __i;                                                     \
    for (__i = 0; __i < BYTES_PER_MP_LIMB; __i++)                       \
      __p[__i] = (char) (__limb >> ((BYTES_PER_MP_LIMB-1 - __i) * 8));  \
  } while (0)
#endif


size_t
mpz_out_raw (FILE *fp, mpz_srcptr x)
{
  mp_size_t   xsize, abs_xsize, bytes, i;
  mp_srcptr   xp;
  char        *tp, *bp;
  mp_limb_t   xlimb;
  int         zeros;
  size_t      tsize, ssize;

  xsize = SIZ(x);
  abs_xsize = ABS (xsize);
  bytes = (abs_xsize * GMP_NUMB_BITS + 7) / 8;
  tsize = ROUND_UP_MULTIPLE ((unsigned) 4, BYTES_PER_MP_LIMB) + bytes;

  tp = __GMP_ALLOCATE_FUNC_TYPE (tsize, char);
  bp = tp + ROUND_UP_MULTIPLE ((unsigned) 4, BYTES_PER_MP_LIMB);

  if (bytes != 0)
    {
      bp += bytes;
      xp = PTR (x);
      i = abs_xsize;

      if (GMP_NAIL_BITS == 0)
	{
	  /* reverse limb order, and byte swap if necessary */
#ifdef _CRAY
	  _Pragma ("_CRI ivdep");
#endif
	  do
	    {
	      bp -= BYTES_PER_MP_LIMB;
	      xlimb = *xp;
	      HTON_LIMB_STORE ((mp_ptr) bp, xlimb);
	      xp++;
	    }
	  while (--i > 0);

	  /* strip high zero bytes (without fetching from bp) */
	  count_leading_zeros (zeros, xlimb);
	  zeros /= 8;
	  bp += zeros;
	  bytes -= zeros;
	}
      else
	{
	  mp_limb_t  new_xlimb;
	  int        bits;
	  ASSERT_CODE (char *bp_orig = bp - bytes);

	  ASSERT_ALWAYS (GMP_NUMB_BITS >= 8);

	  bits = 0;
	  xlimb = 0;
	  for (;;)
	    {
	      while (bits >= 8)
		{
		  ASSERT (bp > bp_orig);
		  *--bp = xlimb & 0xFF;
		  xlimb >>= 8;
		  bits -= 8;
		}

	      if (i == 0)
		break;

	      new_xlimb = *xp++;
	      i--;
	      ASSERT (bp > bp_orig);
	      *--bp = (xlimb | (new_xlimb << bits)) & 0xFF;
	      xlimb = new_xlimb >> (8 - bits);
	      bits += GMP_NUMB_BITS - 8;
	    }

	  if (bits != 0)
	    {
	      ASSERT (bp > bp_orig);
	      *--bp = xlimb;
	    }

	  ASSERT (bp == bp_orig);
	  while (*bp == 0)
	    {
	      bp++;
	      bytes--;
	    }
	}
    }

  /* total bytes to be written */
  ssize = 4 + bytes;

  /* twos complement negative for the size value */
  bytes = (xsize >= 0 ? bytes : -bytes);

  /* so we don't rely on sign extension in ">>" */
  ASSERT_ALWAYS (sizeof (bytes) >= 4);

  bp[-4] = bytes >> 24;
  bp[-3] = bytes >> 16;
  bp[-2] = bytes >> 8;
  bp[-1] = bytes;
  bp -= 4;

  if (fp == 0)
    fp = stdout;
  if (fwrite (bp, ssize, 1, fp) != 1)
    ssize = 0;

  (*__gmp_free_func) (tp, tsize);
  return ssize;
}