www.pudn.com > source.rar > BITS.C

/* ITU-T G.729 Software Package Release 2 (November 2006) */ 
/* 
   ITU-T G.729 Annex C - Reference C code for floating point 
                         implementation of G.729 
                         Version 1.01 of 15.September.98 
*/ 
 
/* 
---------------------------------------------------------------------- 
                    COPYRIGHT NOTICE 
---------------------------------------------------------------------- 
   ITU-T G.729 Annex C ANSI C source code 
   Copyright (C) 1998, AT&T, France Telecom, NTT, University of 
   Sherbrooke.  All rights reserved. 
 
---------------------------------------------------------------------- 
*/ 
 
/* 
 File : BITS.C 
 Used for the floating point version of both 
 G.729 main body and G.729A 
*/ 
 
/*****************************************************************************/ 
/* bit stream manipulation routines                                          */ 
/*****************************************************************************/ 
 
#include "typedef.h" 
#include "version.h" 
#ifdef VER_G729A 
 #include "ld8a.h" 
 #include "tab_ld8a.h" 
#else 
 #include "ld8k.h" 
 #include "tab_ld8k.h" 
#endif 
 
/* prototypes for local functions */ 
 
static void   int2bin(int  value, int  no_of_bits, INT16 *bitstream); 
static int    bin2int(int  no_of_bits, INT16 *bitstream); 
 
/*---------------------------------------------------------------------------- 
 * prm2bits_ld8k -converts encoder parameter vector into vector of serial bits 
 * bits2prm_ld8k - converts serial received bits to  encoder parameter vector 
 * 
 * The transmitted parameters for 8000 bits/sec are: 
 * 
 *     LPC:     1st codebook           7+1 bit 
 *              2nd codebook           5+5 bit 
 * 
 *     1st subframe: 
 *          pitch period                 8 bit 
 *          parity check on 1st period   1 bit 
 *          codebook index1 (positions) 13 bit 
 *          codebook index2 (signs)      4 bit 
 *          pitch and codebook gains   4+3 bit 
 * 
 *     2nd subframe: 
 *          pitch period (relative)      5 bit 
 *          codebook index1 (positions) 13 bit 
 *          codebook index2 (signs)      4 bit 
 *          pitch and codebook gains   4+3 bit 
 * 
 *---------------------------------------------------------------------------- 
 */ 
 
void prm2bits_ld8k( 
 int  prm[],            /* input : encoded parameters  */ 
 INT16 bits[]           /* output: serial bits         */ 
) 
{ 
   int  i; 
   *bits++ = SYNC_WORD;     /* At receiver this bit indicates BFI */ 
   *bits++ = SIZE_WORD;     /* Number of bits in this frame       */ 
 
   for (i = 0; i < PRM_SIZE; i++) 
   { 
      int2bin(prm[i], bitsno[i], bits); 
      bits += bitsno[i]; 
   } 
 
   return; 
} 
 
/*---------------------------------------------------------------------------- 
 * int2bin convert integer to binary and write the bits bitstream array 
 *---------------------------------------------------------------------------- 
 */ 
static void int2bin( 
 int  value,             /* input : decimal value */ 
 int  no_of_bits,        /* input : number of bits to use */ 
 INT16 *bitstream        /* output: bitstream  */ 
) 
{ 
   INT16 *pt_bitstream; 
   int    i, bit; 
 
   pt_bitstream = bitstream + no_of_bits; 
 
   for (i = 0; i < no_of_bits; i++) 
   { 
     bit = value & 0x0001;      /* get lsb */ 
     if (bit == 0) 
         *--pt_bitstream = BIT_0; 
     else 
         *--pt_bitstream = BIT_1; 
     value >>= 1; 
   } 
   return; 
} 
 
/*---------------------------------------------------------------------------- 
 *  bits2prm_ld8k - converts serial received bits to  encoder parameter vector 
 *---------------------------------------------------------------------------- 
 */ 
void bits2prm_ld8k( 
 INT16 bits[],          /* input : serial bits        */ 
 int  prm[]             /* output: decoded parameters */ 
) 
{ 
   int  i; 
   for (i = 0; i < PRM_SIZE; i++) 
   { 
      prm[i] = bin2int(bitsno[i], bits); 
      bits  += bitsno[i]; 
   } 
 
   return; 
} 
 
 
/*---------------------------------------------------------------------------- 
 * bin2int - read specified bits from bit array  and convert to integer value 
 *---------------------------------------------------------------------------- 
 */ 
static int  bin2int(            /* output: decimal value of bit pattern */ 
 int  no_of_bits,        /* input : number of bits to read       */ 
 INT16 *bitstream        /* input : array containing bits        */ 
) 
{ 
   int    value, i; 
   int  bit; 
 
   value = 0; 
   for (i = 0; i < no_of_bits; i++) 
   { 
     value <<= 1; 
     bit = *bitstream++; 
     if (bit == BIT_1)  value += 1; 
   } 
   return(value); 
}