1/* 2 * This source code is a product of Sun Microsystems, Inc. and is provided 3 * for unrestricted use. Users may copy or modify this source code without 4 * charge. 5 * 6 * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING 7 * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 8 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 9 * 10 * Sun source code is provided with no support and without any obligation on 11 * the part of Sun Microsystems, Inc. to assist in its use, correction, 12 * modification or enhancement. 13 * 14 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 15 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE 16 * OR ANY PART THEREOF. 17 * 18 * In no event will Sun Microsystems, Inc. be liable for any lost revenue 19 * or profits or other special, indirect and consequential damages, even if 20 * Sun has been advised of the possibility of such damages. 21 * 22 * Sun Microsystems, Inc. 23 * 2550 Garcia Avenue 24 * Mountain View, California 94043 25 */ 26 27/* 28 * g723_40.c 29 * 30 * Description: 31 * 32 * g723_40_encoder (), g723_40_decoder () 33 * 34 * These routines comprise an implementation of the CCITT G.723 40Kbps 35 * ADPCM coding algorithm. Essentially, this implementation is identical to 36 * the bit level description except for a few deviations which 37 * take advantage of workstation attributes, such as hardware 2's 38 * complement arithmetic. 39 * 40 * The deviation from the bit level specification (lookup tables), 41 * preserves the bit level performance specifications. 42 * 43 * As outlined in the G.723 Recommendation, the algorithm is broken 44 * down into modules. Each section of code below is preceded by 45 * the name of the module which it is implementing. 46 * 47 */ 48 49#include "g72x.h" 50#include "g72x_priv.h" 51 52/* 53 * Maps G.723_40 code word to ructeconstructed scale factor normalized log 54 * magnitude values. 55 */ 56static short _dqlntab [32] = { -2048, -66, 28, 104, 169, 224, 274, 318, 57 358, 395, 429, 459, 488, 514, 539, 566, 58 566, 539, 514, 488, 459, 429, 395, 358, 59 318, 274, 224, 169, 104, 28, -66, -2048 } ; 60 61/* Maps G.723_40 code word to log of scale factor multiplier. */ 62static short _witab [32] = { 448, 448, 768, 1248, 1280, 1312, 1856, 3200, 63 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272, 64 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512, 65 3200, 1856, 1312, 1280, 1248, 768, 448, 448 } ; 66 67/* 68 * Maps G.723_40 code words to a set of values whose long and short 69 * term averages are computed and then compared to give an indication 70 * how stationary (steady state) the signal is. 71 */ 72static short _fitab [32] = { 0, 0, 0, 0, 0, 0x200, 0x200, 0x200, 73 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00, 74 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200, 75 0x200, 0x200, 0x200, 0, 0, 0, 0, 0 } ; 76 77static short qtab_723_40 [15] = { -122, -16, 68, 139, 198, 250, 298, 339, 78 378, 413, 445, 475, 502, 528, 553 } ; 79 80/* 81 * g723_40_encoder () 82 * 83 * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens 84 * the resulting 5-bit CCITT G.723 40Kbps code. 85 * Returns -1 if the input coding value is invalid. 86 */ 87int g723_40_encoder (int sl, G72x_STATE *state_ptr) 88{ 89 short sei, sezi, se, sez ; /* ACCUM */ 90 short d ; /* SUBTA */ 91 short y ; /* MIX */ 92 short sr ; /* ADDB */ 93 short dqsez ; /* ADDC */ 94 short dq, i ; 95 96 /* linearize input sample to 14-bit PCM */ 97 sl >>= 2 ; /* sl of 14-bit dynamic range */ 98 99 sezi = predictor_zero (state_ptr) ; 100 sez = sezi >> 1 ; 101 sei = sezi + predictor_pole (state_ptr) ; 102 se = sei >> 1 ; /* se = estimated signal */ 103 104 d = sl - se ; /* d = estimation difference */ 105 106 /* quantize prediction difference */ 107 y = step_size (state_ptr) ; /* adaptive quantizer step size */ 108 i = quantize (d, y, qtab_723_40, 15) ; /* i = ADPCM code */ 109 110 dq = reconstruct (i & 0x10, _dqlntab [i], y) ; /* quantized diff */ 111 112 sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq ; /* reconstructed signal */ 113 114 dqsez = sr + sez - se ; /* dqsez = pole prediction diff. */ 115 116 update (5, y, _witab [i], _fitab [i], dq, sr, dqsez, state_ptr) ; 117 118 return i ; 119} 120 121/* 122 * g723_40_decoder () 123 * 124 * Decodes a 5-bit CCITT G.723 40Kbps code and returns 125 * the resulting 16-bit linear PCM, A-law or u-law sample value. 126 * -1 is returned if the output coding is unknown. 127 */ 128int g723_40_decoder (int i, G72x_STATE *state_ptr) 129{ 130 short sezi, sei, sez, se ; /* ACCUM */ 131 short y ; /* MIX */ 132 short sr ; /* ADDB */ 133 short dq ; 134 short dqsez ; 135 136 i &= 0x1f ; /* mask to get proper bits */ 137 sezi = predictor_zero (state_ptr) ; 138 sez = sezi >> 1 ; 139 sei = sezi + predictor_pole (state_ptr) ; 140 se = sei >> 1 ; /* se = estimated signal */ 141 142 y = step_size (state_ptr) ; /* adaptive quantizer step size */ 143 dq = reconstruct (i & 0x10, _dqlntab [i], y) ; /* estimation diff. */ 144 145 sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq) ; /* reconst. signal */ 146 147 dqsez = sr - se + sez ; /* pole prediction diff. */ 148 149 update (5, y, _witab [i], _fitab [i], dq, sr, dqsez, state_ptr) ; 150 151 return arith_shift_left (sr, 2) ; /* sr was of 14-bit dynamic range */ 152} 153 154