add.c File Reference

#include <stdio.h>
#include <assert.h>
#include "private.h"
#include "gsm.h"
#include "proto.h"

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

Functions
word gsm_abs	P1 ((a), word a)
word gsm_norm	P1 ((a), longword a)
word gsm_add	P2 ((a, b), word a, word b)
longword gsm_L_add	P2 ((a, b), longword a, longword b)
longword gsm_L_asl	P2 ((a, n), longword a, int n)
word gsm_asl	P2 ((a, n), word a, int n)
word gsm_div	P2 ((num, denum), word num, word denum)

Variables
static unsigned char const	bitoff [256]

Macro Definition Documentation

saturate

#define saturate

(

x

)

((x) < MIN_WORD ? MIN_WORD : (x) > MAX_WORD ? MAX_WORD: (x))

Definition at line 20 of file add.c.

Referenced by P2().

Function Documentation

P1() [1/2]

word gsm_abs P1	(	(a)	,
		word	a
	)

Definition at line 51 of file add.c.

References a, MAX_WORD, MIN_WORD, and P2().

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

P1() [2/2]

word gsm_norm P1	(	(a)	,
		longword	a
	)

Definition at line 117 of file add.c.

References a.

{
   assert(a != 0);

   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 ] );
}

P2() [1/5]

longword gsm_L_mult P2	(	(a, b)	,
		word	a,
		word	b
	)

Definition at line 23 of file add.c.

References a, b, MAX_WORD, MIN_WORD, SASR, and saturate.

Referenced by P1(), and P2().

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

P2() [2/5]

longword gsm_L_sub P2	(	(a, b)	,
		longword	a,
		longword	b
	)

Definition at line 62 of file add.c.

References b, MAX_LONGWORD, MIN_LONGWORD, and P2().

{
   if (a < 0) {
      if (b >= 0) return a + b;
      else {
         ulongword A = (ulongword)-(a + 1) + (ulongword)-(b + 1);
         return A >= MAX_LONGWORD ? MIN_LONGWORD :-(longword)A-2;
      }
   }
   else if (b <= 0) return a + b;
   else {
      ulongword A = (ulongword)a + (ulongword)b;
      return A > MAX_LONGWORD ? MAX_LONGWORD : A;
   }
}

P2() [3/5]

longword gsm_L_asr P2	(	(a, n)	,
		longword	a,
		int	n
	)

Definition at line 153 of file add.c.

{
   if (n >= 32) return 0;
   if (n <= -32) return -(a < 0);
   if (n < 0) return gsm_L_asr(a, -n);
   return a << n;
}

P2() [4/5]

word gsm_asr P2	(	(a, n)	,
		word	a,
		int	n
	)

Definition at line 161 of file add.c.

References P2().

{
   if (n >= 16) return 0;
   if (n <= -16) return -(a < 0);
   if (n < 0) return gsm_asr(a, -n);
   return a << n;
}

P2() [5/5]

word gsm_div P2	(	(num, denum)	,
		word	num,
		word	denum
	)

Definition at line 206 of file add.c.

{
   longword L_num   = num;
   longword L_denum = denum;
   word     div   = 0;
   int      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.
    */

   /* assert(num != 0); */

   assert(num >= 0 && denum >= num);
   if (num == 0)
       return 0;

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

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

   return div;
}

Variable Documentation

bitoff

unsigned char const bitoff[256]

static

Definition at line 98 of file add.c.