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00030 #include "asterisk.h"
00031
00032 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 369001 $")
00033
00034 #include "asterisk/alaw.h"
00035 #include "asterisk/logger.h"
00036
00037 #ifndef G711_NEW_ALGORITHM
00038 #define AMI_MASK 0x55
00039
00040 static inline unsigned char linear2alaw(short int linear)
00041 {
00042 int mask;
00043 int seg;
00044 int pcm_val;
00045 static int seg_end[8] =
00046 {
00047 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF
00048 };
00049
00050 pcm_val = linear;
00051 if (pcm_val >= 0) {
00052
00053 mask = AMI_MASK | 0x80;
00054 } else {
00055
00056 mask = AMI_MASK;
00057 pcm_val = -pcm_val;
00058 }
00059
00060
00061 for (seg = 0; seg < 8; seg++) {
00062 if (pcm_val <= seg_end[seg]) {
00063 break;
00064 }
00065 }
00066
00067 return ((seg << 4) | ((pcm_val >> ((seg) ? (seg + 3) : 4)) & 0x0F)) ^ mask;
00068 }
00069 #else
00070 static unsigned char linear2alaw(short sample, int full_coding)
00071 {
00072 static const unsigned exp_lut[128] = {
00073 1,1,2,2,3,3,3,3,
00074 4,4,4,4,4,4,4,4,
00075 5,5,5,5,5,5,5,5,
00076 5,5,5,5,5,5,5,5,
00077 6,6,6,6,6,6,6,6,
00078 6,6,6,6,6,6,6,6,
00079 6,6,6,6,6,6,6,6,
00080 6,6,6,6,6,6,6,6,
00081 7,7,7,7,7,7,7,7,
00082 7,7,7,7,7,7,7,7,
00083 7,7,7,7,7,7,7,7,
00084 7,7,7,7,7,7,7,7,
00085 7,7,7,7,7,7,7,7,
00086 7,7,7,7,7,7,7,7,
00087 7,7,7,7,7,7,7,7,
00088 7,7,7,7,7,7,7,7 };
00089 unsigned sign, exponent, mantissa, mag;
00090 unsigned char alawbyte;
00091
00092 ast_alaw_get_sign_mag(sample, &sign, &mag);
00093 if (mag > 32767)
00094 mag = 32767;
00095
00096 exponent = exp_lut[(mag >> 8) & 0x7f];
00097 mantissa = (mag >> (exponent + 3)) & 0x0f;
00098 if (mag < 0x100)
00099 exponent = 0;
00100
00101 if (full_coding) {
00102
00103 alawbyte = (unsigned char)(sign | (exponent << 4) | mantissa);
00104 alawbyte ^= AST_ALAW_AMI_MASK;
00105 } else {
00106
00107 alawbyte = (exponent << 4) | mantissa;
00108 }
00109 return alawbyte;
00110 }
00111 #endif
00112
00113 #ifndef G711_NEW_ALGORITHM
00114 static inline short int alaw2linear (unsigned char alaw)
00115 {
00116 int i;
00117 int seg;
00118
00119 alaw ^= AMI_MASK;
00120 i = ((alaw & 0x0F) << 4) + 8 ;
00121 seg = (((int) alaw & 0x70) >> 4);
00122 if (seg) {
00123 i = (i + 0x100) << (seg - 1);
00124 }
00125 return (short int) ((alaw & 0x80) ? i : -i);
00126 }
00127 #else
00128 static inline short alaw2linear(unsigned char alawbyte)
00129 {
00130 unsigned exponent, mantissa;
00131 short sample;
00132
00133 alawbyte ^= AST_ALAW_AMI_MASK;
00134 exponent = (alawbyte & 0x70) >> 4;
00135 mantissa = alawbyte & 0x0f;
00136 sample = (mantissa << 4) + 8 ;
00137 if (exponent)
00138 sample = (sample + 0x100) << (exponent - 1);
00139 if (!(alawbyte & 0x80))
00140 sample = -sample;
00141 return sample;
00142 }
00143 #endif
00144
00145
00146
00147 #ifndef G711_NEW_ALGORITHM
00148 unsigned char __ast_lin2a[8192];
00149 #else
00150 unsigned char __ast_lin2a[AST_ALAW_TAB_SIZE];
00151 #endif
00152 short __ast_alaw[256];
00153
00154 void ast_alaw_init(void)
00155 {
00156 int i;
00157
00158
00159
00160 #ifndef G711_NEW_ALGORITHM
00161 for (i = 0; i < 256; i++) {
00162 __ast_alaw[i] = alaw2linear(i);
00163 }
00164
00165 for (i = -32768; i < 32768; i++) {
00166 __ast_lin2a[((unsigned short)i) >> 3] = linear2alaw(i);
00167 }
00168 #else
00169 for (i = 0; i < 256; i++) {
00170 __ast_alaw[i] = alaw2linear(i);
00171 }
00172
00173 for (i = 0; i <= 32768; i += AST_ALAW_STEP) {
00174 AST_LIN2A_LOOKUP(i) = linear2alaw(i, 0 );
00175 }
00176 #endif
00177
00178 #ifdef TEST_CODING_TABLES
00179 for (i = -32768; i < 32768; ++i) {
00180 #ifndef G711_NEW_ALGORITHM
00181 unsigned char e1 = linear2alaw(i);
00182 #else
00183 unsigned char e1 = linear2alaw(i, 1);
00184 #endif
00185 short d1 = alaw2linear(e1);
00186 unsigned char e2 = AST_LIN2A(i);
00187 short d2 = alaw2linear(e2);
00188 short d3 = AST_ALAW(e1);
00189
00190 if (e1 != e2 || d1 != d3 || d2 != d3) {
00191 ast_log(LOG_WARNING, "a-Law coding tables test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d\n",
00192 i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2);
00193 }
00194 }
00195 ast_log(LOG_NOTICE, "a-Law coding tables test complete.\n");
00196 #endif
00197
00198 #ifdef TEST_TANDEM_TRANSCODING
00199
00200 for (i = -32768; i < 32768; ++i) {
00201 unsigned char e1 = AST_LIN2A(i);
00202 short d1 = AST_ALAW(e1);
00203 unsigned char e2 = AST_LIN2A(d1);
00204 short d2 = AST_ALAW(e2);
00205 unsigned char e3 = AST_LIN2A(d2);
00206 short d3 = AST_ALAW(e3);
00207
00208 if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) {
00209 ast_log(LOG_WARNING, "a-Law tandem transcoding test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d, d3=%d\n",
00210 i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2, (int)d3);
00211 }
00212 }
00213 ast_log(LOG_NOTICE, "a-Law tandem transcoding test complete.\n");
00214 #endif
00215
00216 }
00217