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_24.c 29 * 30 * Description: 31 * 32 * g723_24_encoder (), g723_24_decoder () 33 * 34 * These routines comprise an implementation of the CCITT G.723 24 Kbps 35 * ADPCM coding algorithm. Essentially, this implementation is identical to 36 * the bit level description except for a few deviations which take advantage 37 * of workstation attributes, such as hardware 2's complement arithmetic. 38 * 39 */ 40 41#include "g72x.h" 42#include "g72x_priv.h" 43 44/* 45 * Maps G.723_24 code word to reconstructed scale factor normalized log 46 * magnitude values. 47 */ 48static short _dqlntab [8] = { -2048, 135, 273, 373, 373, 273, 135, -2048 } ; 49 50/* Maps G.723_24 code word to log of scale factor multiplier. */ 51static short _witab [8] = { -128, 960, 4384, 18624, 18624, 4384, 960, -128 } ; 52 53/* 54 * Maps G.723_24 code words to a set of values whose long and short 55 * term averages are computed and then compared to give an indication 56 * how stationary (steady state) the signal is. 57 */ 58static short _fitab [8] = { 0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0 } ; 59 60static short qtab_723_24 [3] = { 8, 218, 331 } ; 61 62/* 63 * g723_24_encoder () 64 * 65 * Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code. 66 * Returns -1 if invalid input coding value. 67 */ 68int 69g723_24_encoder ( 70 int sl, 71 G72x_STATE *state_ptr) 72{ 73 short sei, sezi, se, sez ; /* ACCUM */ 74 short d ; /* SUBTA */ 75 short y ; /* MIX */ 76 short sr ; /* ADDB */ 77 short dqsez ; /* ADDC */ 78 short dq, i ; 79 80 /* linearize input sample to 14-bit PCM */ 81 sl >>= 2 ; /* sl of 14-bit dynamic range */ 82 83 sezi = predictor_zero (state_ptr) ; 84 sez = sezi >> 1 ; 85 sei = sezi + predictor_pole (state_ptr) ; 86 se = sei >> 1 ; /* se = estimated signal */ 87 88 d = sl - se ; /* d = estimation diff. */ 89 90 /* quantize prediction difference d */ 91 y = step_size (state_ptr) ; /* quantizer step size */ 92 i = quantize (d, y, qtab_723_24, 3) ; /* i = ADPCM code */ 93 dq = reconstruct (i & 4, _dqlntab [i], y) ; /* quantized diff. */ 94 95 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq ; /* reconstructed signal */ 96 97 dqsez = sr + sez - se ; /* pole prediction diff. */ 98 99 update (3, y, _witab [i], _fitab [i], dq, sr, dqsez, state_ptr) ; 100 101 return i ; 102} 103 104/* 105 * g723_24_decoder () 106 * 107 * Decodes a 3-bit CCITT G.723_24 ADPCM code and returns 108 * the resulting 16-bit linear PCM, A-law or u-law sample value. 109 * -1 is returned if the output coding is unknown. 110 */ 111int 112g723_24_decoder ( 113 int i, 114 G72x_STATE *state_ptr) 115{ 116 short sezi, sei, sez, se ; /* ACCUM */ 117 short y ; /* MIX */ 118 short sr ; /* ADDB */ 119 short dq ; 120 short dqsez ; 121 122 i &= 0x07 ; /* mask to get proper bits */ 123 sezi = predictor_zero (state_ptr) ; 124 sez = sezi >> 1 ; 125 sei = sezi + predictor_pole (state_ptr) ; 126 se = sei >> 1 ; /* se = estimated signal */ 127 128 y = step_size (state_ptr) ; /* adaptive quantizer step size */ 129 dq = reconstruct (i & 0x04, _dqlntab [i], y) ; /* unquantize pred diff */ 130 131 sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq) ; /* reconst. signal */ 132 133 dqsez = sr - se + sez ; /* pole prediction diff. */ 134 135 update (3, y, _witab [i], _fitab [i], dq, sr, dqsez, state_ptr) ; 136 137 return arith_shift_left (sr, 2) ; /* sr was of 14-bit dynamic range */ 138} 139 140