add.c

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/*
+--------------------------------------------------------------------------+
| CHStone : a suite of benchmark programs for C-based High-Level Synthesis |
| ======================================================================== |
|                                                                          |
| * Collected and Modified : Y. Hara, H. Tomiyama, S. Honda,               |
|                            H. Takada and K. Ishii                        |
|                            Nagoya University, Japan                      |
|                                                                          |
| * Remark :                                                               |
|    1. This source code is modified to unify the formats of the benchmark |
|       programs in CHStone.                                               |
|    2. Test vectors are added for CHStone.                                |
|    3. If "main_result" is 0 at the end of the program, the program is    |
|       correctly executed.                                                |
|    4. Please follow the copyright of each benchmark program.             |
+--------------------------------------------------------------------------+
*/
/*
 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
 * Universitaet Berlin.  See the accompanying file "COPYRIGHT" for
 * details.  THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
 */

/* $Header: /home/kbs/jutta/src/gsm/gsm-1.0/src/RCS/add.c,v 1.5 1994/12/30 22:35:09 jutta Exp $ */

/*
 *  See private.h for the more commonly used macro versions.
 */

#define saturate(x)     \
        ((x) < MIN_WORD ? MIN_WORD : (x) > MAX_WORD ? MAX_WORD: (x))

word
gsm_add (word a, word b)
{
  longword sum;
  sum = (longword) a + (longword) b;
  return saturate (sum);
}

word
gsm_mult (word a, word b)
{
  if (a == MIN_WORD && b == MIN_WORD)
    return MAX_WORD;
  else
    return SASR ((longword) a * (longword) b, 15);
}

word
gsm_mult_r (word a, word b)
{
  longword prod;
  if (b == MIN_WORD && a == MIN_WORD)
    return MAX_WORD;
  else
    {
      prod = (longword) a *(longword) b + 16384;
      prod >>= 15;
      return prod & 0xFFFF;
    }
}

word
gsm_abs (word a)
{
  return a < 0 ? (a == MIN_WORD ? MAX_WORD : -a) : a;
}

const unsigned char bitoff[256] = {
  8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
  3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

word
gsm_norm (longword a)
/*
 * the number of left shifts needed to normalize the 32 bit
 * variable L_var1 for positive values on the interval
 *
 * with minimum of
 * minimum of 1073741824  (01000000000000000000000000000000) and 
 * maximum of 2147483647  (01111111111111111111111111111111)
 *
 *
 * and for negative values on the interval with
 * minimum of -2147483648 (-10000000000000000000000000000000) and
 * maximum of -1073741824 ( -1000000000000000000000000000000).
 *
 * in order to normalize the result, the following
 * operation must be done: L_norm_var1 = L_var1 << norm( L_var1 );
 *
 * (That's 'ffs', only from the left, not the right..)
 */
{

  if (a < 0)
    {
      if (a <= -1073741824)
        return 0;
      a = ~a;
    }

  return a & 0xffff0000 ?
    (a & 0xff000000 ? -1 + bitoff[0xFF & (a >> 24)] :
     7 + bitoff[0xFF & (a >> 16)])
    : (a & 0xff00 ? 15 + bitoff[0xFF & (a >> 8)] : 23 + bitoff[0xFF & a]);
}

word
gsm_div (word num, word denum)
{
  longword L_num;
  longword L_denum;
  word div;
  int k;

  L_num = num;
  L_denum = denum;
  div = 0;
  k = 15;
  /* The parameter num sometimes becomes zero.
   * Although this is explicitly guarded against in 4.2.5,
   * we assume that the result should then be zero as well.
   */

  if (num == 0)
    return 0;

  while (k--)
    {
      div <<= 1;
      L_num <<= 1;

      if (L_num >= L_denum)
        {
          L_num -= L_denum;
          div++;
        }
    }

  return div;
}