math_lib.c

2400bps MELP语音编解码源程序。

/*

2.4 kbps MELP Proposed Federal Standard speech coder

Fixed-point C code, version 1.0

Copyright (c) 1998, Texas Instruments, Inc.  

Texas Instruments has intellectual property rights on the MELP
algorithm.  The Texas Instruments contact for licensing issues for
commercial and non-government use is William Gordon, Director,
Government Contracts, Texas Instruments Incorporated, Semiconductor
Group (phone [phone]).

The fixed-point version of the voice codec Mixed Excitation Linear
Prediction (MELP) is based on specifications on the C-language software
simulation contained in GSM 06.06 which is protected by copyright and
is the property of the European Telecommunications Standards Institute
(ETSI). This standard is available from the ETSI publication office
tel. [phone]. ETSI has granted a license to United States
Department of Defense to use the C-language software simulation contained
in GSM 06.06 for the purposes of the development of a fixed-point
version of the voice codec Mixed Excitation Linear Prediction (MELP).
Requests for authorization to make other use of the GSM 06.06 or
otherwise distribute or modify them need to be addressed to the ETSI
Secretariat fax: [phone].

*/
#include <stdio.h>
#include <math.h>
#include "spbstd.h"
#include "mathhalf.h"
#include "mathdp31.h"
#include "wmops.h"
#include "math_lib.h"
#include "constant.h"

extern int complexity;
extern int saturation;

Shortword DEBUG;

/***************************************************************************
 *
 *   FUNCTION NAME: L_divider2
 *
 *   PURPOSE:
 *
 *     Divide numer by denom.  If numer is bigger than denom, a warning
 *     is given and a zero is returned.
 *
 *
 *   INPUTS:
 *
 *     numer
 *                     32 bit long signed integer (Longword).
 *     denom
 *                     32 bit long signed integer (Longword).
 *     numer_shift
 *                     16 bit short signed integer (Shortword) represents
 *                     number of right shifts for numer.
 *     denom_shift
 *                     16 bit short signed integer (Shortword) represents
 *                     number of left shifts for denom.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     result
 *                     16 bit short signed integer (Shortword).
 *
 *************************************************************************/
Shortword L_divider2(Longword numer, Longword denom, Shortword numer_shift, 
		     Shortword denom_shift)
{
  
  Shortword result;
  Shortword sign=0;
  Shortword short_shift=0;
  Longword L_temp;
  
  DEBUG = 1;

  if (denom==0&& DEBUG )
    printf("L_divider2: division by 0\n");
  
  /* increment complexity for if statement */
  compare_zero();
  if (numer<0) {
    sign = !sign;    data_move();
  }
  /* increment complexity for if statement */
  compare_zero();
  if (denom<0) {
    sign = !sign;    data_move();
  }

  L_temp = L_shl(denom, denom_shift);
  denom = L_abs(L_temp);    L_data_move();
  L_temp = L_shr(numer, numer_shift);
  numer = L_abs(L_temp);    L_data_move();
  
  while (denom>(Longword)SW_MAX)
    {
      /* increment complexity for while statement */
      L_compare_nonzero();

      denom = L_shr(denom,1);    L_data_move();
      short_shift = add(short_shift,1);    data_move();
    }
  numer = L_shr(numer, short_shift);    L_data_move();

  if (numer > denom && DEBUG)
      printf("warning: L_divide2>1: numer %.1f times denom\n",
	     (float)numer / (float)denom);
  
  result = divide_s(extract_l(numer),extract_l(denom));
  
  /* increment complexity for if statement */
  compare_zero();
  if (sign) {
    result = negate(result);    data_move();
  }

  return(result);
} /* L_divider2 */


/***************************************************************************
 *
 *   FUNCTION NAME: log10_fxp
 *
 *   PURPOSE:
 *
 *     Compute the logarithm to the base 10 of x.
 *
 *
 *   INPUTS:
 *
 *     x
 *                     16 bit short signed integer (Shortword).
 *     Q
 *                     16 bit short signed integer (Shortword) represents
 *                     Q value of x.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     y
 *                     16 bit short signed integer (Shortword) in Q12.
 *
 *************************************************************************/
Shortword log10_fxp(Shortword x, Shortword Q)
{
  /* table is Q13 */
  static Shortword table[256]=
  {
    0, 2466, 3908, 4932, 5725, 6374, 6923, 7398, 7817, 8192, 
    8531, 8840, 9125, 9389, 9634, 9864, 10079, 10283, 10475, 10658, 
    10831, 10997, 11155, 11306, 11451, 11591, 11725, 11855, 11979, 12100, 
    12217, 12330, 12439, 12545, 12649, 12749, 12846, 12941, 13034, 13124, 
    13211, 13297, 13381, 13463, 13543, 13621, 13697, 13772, 13846, 13917, 
    13988, 14057, 14125, 14191, 14257, 14321, 14384, 14446, 14506, 14566, 
    14625, 14683, 14740, 14796, 14851, 14905, 14959, 15011, 15063, 15115, 
    15165, 15215, 15264, 15312, 15360, 15407, 15454, 15500, 15545, 15590, 
    15634, 15677, 15721, 15763, 15805, 15847, 15888, 15929, 15969, 16009, 
    16048, 16087, 16125, 16163, 16201, 16238, 16275, 16312, 16348, 16384, 
    16419, 16454, 16489, 16523, 16557, 16591, 16624, 16657, 16690, 16723, 
    16755, 16787, 16818, 16850, 16881, 16912, 16942, 16972, 17002, 17032, 
    17062, 17091, 17120, 17149, 17177, 17206, 17234, 17262, 17289, 17317, 
    17344, 17371, 17398, 17425, 17451, 17477, 17504, 17529, 17555, 17581, 
    17606, 17631, 17656, 17681, 17705, 17730, 17754, 17778, 17802, 17826, 
    17850, 17873, 17896, 17920, 17943, 17966, 17988, 18011, 18033, 18056, 
    18078, 18100, 18122, 18144, 18165, 18187, 18208, 18229, 18250, 18271, 
    18292, 18313, 18334, 18354, 18374, 18395, 18415, 18435, 18455, 18475, 
    18494, 18514, 18533, 18553, 18572, 18591, 18610, 18629, 18648, 18667, 
    18686, 18704, 18723, 18741, 18759, 18778, 18796, 18814, 18832, 18850, 
    18867, 18885, 18903, 18920, 18937, 18955, 18972, 18989, 19006, 19023, 
    19040, 19057, 19074, 19090, 19107, 19123, 19140, 19156, 19172, 19189, 
    19205, 19221, 19237, 19253, 19269, 19284, 19300, 19316, 19331, 19347, 
    19362, 19378, 19393, 19408, 19423, 19438, 19453, 19468, 19483, 19498, 
    19513, 19528, 19542, 19557, 19572, 19586, 19600, 19615, 19629, 19643, 
    19658, 19672, 19686, 19700, 19714, 19728 };
  
    Shortword y, interp_factor, interp_component;
    Shortword index1, index2;
    Shortword shift;
    Shortword temp1, temp2;
    Longword L_temp;
    
    shift = sub(7,Q);        data_move();

    /* increment complexity for if statement */
    compare_zero();
    if (!x)
      {	
	return(-SW_MAX);
      }

    while( !(index2=shr(x,7)) && x)
      {
	/* increment complexity for while statement */
	data_move();    compare_zero();

	x=shl(x,1);    data_move();
	shift = sub(shift,1);    data_move();
      }
    index1 = sub(index2,1);    data_move();
    
    /* interpolation */
    interp_factor = shl((Shortword)(x&127),8);   logic();
    temp1 = sub(table[index2],table[index1]);
    interp_component = mult(temp1,interp_factor);        data_move();
	
    /* return a Q12 */
    L_temp = L_mult(table[1],shift);
    L_temp = L_shr(L_temp,2);
    temp1 = shr(table[index1],1);
    temp1 = add(temp1,extract_l(L_temp));
    temp2 = shr(interp_component,1);
    y = add(temp1,temp2);    data_move();

    return(y);
} /* log10_fxp */


/***************************************************************************
 *
 *   FUNCTION NAME: L_log10_fxp
 *
 *   PURPOSE:
 *
 *     Compute the logarithm to the base 10 of x.
 *
 *
 *   INPUTS:
 *
 *     x
 *                     32 bit long signed integer (Longword).
 *     Q
 *                     16 bit short signed integer (Shortword) represents
 *                     Q value of x.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     y
 *                     16 bit short signed integer (Shortword) in Q11.
 *
 *************************************************************************/
Shortword L_log10_fxp(Longword x, Shortword Q)
{
  /* table is Q13 */
  static Shortword table[256]=
  {
    0, 2466, 3908, 4932, 5725, 6374, 6923, 7398, 7817, 8192, 
    8531, 8840, 9125, 9389, 9634, 9864, 10079, 10283, 10475, 10658, 
    10831, 10997, 11155, 11306, 11451, 11591, 11725, 11855, 11979, 12100, 
    12217, 12330, 12439, 12545, 12649, 12749, 12846, 12941, 13034, 13124, 
    13211, 13297, 13381, 13463, 13543, 13621, 13697, 13772, 13846, 13917, 
    13988, 14057, 14125, 14191, 14257, 14321, 14384, 14446, 14506, 14566, 
    14625, 14683, 14740, 14796, 14851, 14905, 14959, 15011, 15063, 15115, 
    15165, 15215, 15264, 15312, 15360, 15407, 15454, 15500, 15545, 15590, 
    15634, 15677, 15721, 15763, 15805, 15847, 15888, 15929, 15969, 16009, 
    16048, 16087, 16125, 16163, 16201, 16238, 16275, 16312, 16348, 16384, 
    16419, 16454, 16489, 16523, 16557, 16591, 16624, 16657, 16690, 16723, 
    16755, 16787, 16818, 16850, 16881, 16912, 16942, 16972, 17002, 17032, 
    17062, 17091, 17120, 17149, 17177, 17206, 17234, 17262, 17289, 17317, 
    17344, 17371, 17398, 17425, 17451, 17477, 17504, 17529, 17555, 17581, 
    17606, 17631, 17656, 17681, 17705, 17730, 17754, 17778, 17802, 17826, 
    17850, 17873, 17896, 17920, 17943, 17966, 17988, 18011, 18033, 18056, 
    18078, 18100, 18122, 18144, 18165, 18187, 18208, 18229, 18250, 18271, 
    18292, 18313, 18334, 18354, 18374, 18395, 18415, 18435, 18455, 18475, 
    18494, 18514, 18533, 18553, 18572, 18591, 18610, 18629, 18648, 18667, 
    18686, 18704, 18723, 18741, 18759, 18778, 18796, 18814, 18832, 18850, 
    18867, 18885, 18903, 18920, 18937, 18955, 18972, 18989, 19006, 19023, 
    19040, 19057, 19074, 19090, 19107, 19123, 19140, 19156, 19172, 19189, 
    19205, 19221, 19237, 19253, 19269, 19284, 19300, 19316, 19331, 19347, 
    19362, 19378, 19393, 19408, 19423, 19438, 19453, 19468, 19483, 19498, 
    19513, 19528, 19542, 19557, 19572, 19586, 19600, 19615, 19629, 19643, 
    19658, 19672, 19686, 19700, 19714, 19728 };
  
    Shortword y, interp_component;
    Longword interp_factor;    
    Shortword index1, index2;
    Shortword shift;
    Shortword temp1, temp2;
    Longword L_temp;
    
    
    shift = sub(23,Q);        data_move();

    /* increment complexity for if statement */
    compare_zero();
    if (!x)
      {	
	return((Shortword)-SW_MAX);
      }
    

    while( !(index2=extract_l(L_shr(x,23))) && x)
      {
	/* increment complexity for while statement */
	compare_zero();    data_move();

	x=L_shl(x,1);
	shift = sub(shift,1);    data_move();
      }
    index1 = sub(index2,1);    data_move();
    
    
    /* interpolation */
    interp_factor = L_shl(x&(Longword)0x7fffff, 8);    L_logic();
    temp1 = sub(table[index2],table[index1]);
    interp_component = extract_h(L_mpy_ls(interp_factor,temp1));

	
    /* return a Q11 */
    L_temp = L_mult(table[1],shift);       /* log10(2^shift) */
    L_temp = L_shr(L_temp,3);
    temp1 = shr(table[index1],2);
    temp1 = add(temp1,extract_l(L_temp));
    temp2 = shr(interp_component,2);
    y = add(temp1,temp2);   data_move();
    
      
    return(y);
} /* L_log10_fxp */


/***************************************************************************
 *
 *   FUNCTION NAME: pow10_fxp
 *
 *   PURPOSE:
 *
 *     Compute 10 raised to the power x.
 *
 *
 *   INPUTS:
 *
 *     x
 *                     16 bit short signed integer (Shortword) in Q12.
 *     Q
 *                     16 bit short signed integer (Shortword) represents
 *                     required Q value of returned result.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     y
 *                     16 bit short signed integer (Shortword).
 *
 *************************************************************************/
Shortword pow10_fxp(Shortword x, Shortword Q)
{
  /* table in Q11 */
  Shortword table[257]=
  {
    2048, 2066, 2085, 2104, 2123, 2142, 2161, 2181, 2200, 2220, 
    2240, 2260, 2281, 2302, 2322, 2343, 2364, 2386, 2407, 2429, 
    2451, 2473, 2496, 2518, 2541, 2564, 2587, 2610, 2634, 2658, 
    2682, 2706, 2731, 2755, 2780, 2805, 2831, 2856, 2882, 2908, 
    2934, 2961, 2988, 3015, 3042, 3069, 3097, 3125, 3153, 3182, 
    3211, 3240, 3269, 3298, 3328, 3358, 3389, 3419, 3450, 3481, 
    3513, 3544, 3576, 3609, 3641, 3674, 3708, 3741, 3775, 3809, 
    3843, 3878, 3913, 3948, 3984, 4020, 4056, 4093, 4130, 4167, 
    4205, 4243, 4281, 4320, 4359, 4399, 4438, 4478, 4519, 4560, 
    4601, 4643, 4684, 4727, 4769, 4813, 4856, 4900, 4944, 4989, 
    5034, 5079, 5125, 5172, 5218, 5266, 5313, 5361, 5410, 5458, 
    5508, 5558, 5608, 5658, 5710, 5761, 5813, 5866, 5919, 5972, 
    6026, 6081, 6136, 6191, 6247, 6303, 6360, 6418, 6476, 6534, 
    6593, 6653, 6713, 6774, 6835, 6897, 6959, 7022, 7085, 7149, 
    7214, 7279, 7345, 7411, 7478, 7546, 7614, 7683, 7752, 7822, 
    7893, 7964, 8036, 8109, 8182, 8256, 8331, 8406, 8482, 8559, 
    8636, 8714, 8793, 8872, 8952, 9033, 9115, 9197, 9280, 9364, 
    9449, 9534, 9620, 9707, 9795, 9883, 9973, 10063, 10154, 10245, 
    10338, 10431, 10526, 10621, 10717, 10813, 10911, 11010, 11109, 11210, 
    11311, 11413, 11516, 11620, 11725, 11831, 11938, 12046, 12155, 12265, 
    12375, 12487, 12600, 12714, 12829, 12945, 13062, 13180, 13299, 13419, 
    13540, 13663, 13786, 13911, 14036, 14163, 14291, 14420, 14550, 14682, 
    14815, 14948, 15084, 15220, 15357, 15496, 15636, 15777, 15920, 16064, 
    16209, 16355, 16503, 16652, 16803, 16955, 17108, 17262, 17418, 17576, 
    17734, 17895, 18056, 18220, 18384, 18550, 18718, 18887, 19058, 19230, 
    19404, 19579, 19756, 19934, 20114, 20296, 20480 };