mpir/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 2.1 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; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */

#include <stdio.h>
#include "mpir.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

/* In order to allow mpz_out_raw() to be called from MPIR.Net, its implementation has been refactored into two separate functions.
   Both the contract and implementation of mpz_out_raw() were unchanged, the split was made in order for MPIR.Net to access intermediate variables.
   The basic flow of mpz_out_raw is to 1) allocate scratch memory, 2) write output there, 3) write the output to a file, and 4) free memory.
   Of these, step 2 represents the bulk of the entire operation.
   The new mpz_out_raw_m() function below performs steps 1 and 2.  At that point, local state is saved to the mpir_out struct.
   mpz_out_raw() now calls into mpz_out_raw_m() and completes the remaining steps (3 and 4) using the saved local state.
   For MPIR.Net, file I/O is done differently.  MPIR.Net calls into mpz_out_raw_m(), then performs its own step 3 and duplicates step 4. */
void mpz_out_raw_m (mpir_out_ptr mpir_out, 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 */
          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;

  mpir_out->allocated = tp;
  mpir_out->allocatedSize = tsize;
  mpir_out->written = bp;
  mpir_out->writtenSize = ssize;
}

size_t
mpz_out_raw (FILE* fp, mpz_srcptr x)
{
  mpir_out_struct out;

  if (fp == 0)
    fp = stdout;

  //For re-use in MPIR.Net, the bulk of the work (output into a memory location) has been refactored into a separate function mpz_out_raw_m().
  mpz_out_raw_m(out, x);

  if (fwrite (out->written, out->writtenSize, 1, fp) != 1)
    out->writtenSize = 0;

  (*__gmp_free_func) (out->allocated, out->allocatedSize);
  return out->writtenSize;
}