1 /* 2 3 * l1oip_codec.c generic codec using lookup table 4 * -> conversion from a-Law to u-Law 5 * -> conversion from u-Law to a-Law 6 * -> compression by reducing the number of sample resolution to 4 7 * 8 * NOTE: It is not compatible with any standard codec like ADPCM. 9 * 10 * Author Andreas Eversberg (jolly@eversberg.eu) 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License as published by 14 * the Free Software Foundation; either version 2, or (at your option) 15 * any later version. 16 * 17 * This program is distributed in the hope that it will be useful, 18 * but WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 * GNU General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with this program; if not, write to the Free Software 24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 25 26 */ 27 28 /* 29 30 How the codec works: 31 -------------------- 32 33 The volume is increased to increase the dynamic range of the audio signal. 34 Each sample is converted to a-LAW with only 16 steps of level resolution. 35 A pair of two samples are stored in one byte. 36 37 The first byte is stored in the upper bits, the second byte is stored in the 38 lower bits. 39 40 To speed up compression and decompression, two lookup tables are formed: 41 42 - 16 bits index for two samples (law encoded) with 8 bit compressed result. 43 - 8 bits index for one compressed data with 16 bits decompressed result. 44 45 NOTE: The bytes are handled as they are law-encoded. 46 47 */ 48 49 #include <linux/vmalloc.h> 50 #include <linux/mISDNif.h> 51 #include <linux/in.h> 52 #include "core.h" 53 #include "l1oip.h" 54 55 /* definitions of codec. don't use calculations, code may run slower. */ 56 57 static u8 *table_com; 58 static u16 *table_dec; 59 60 61 /* alaw -> ulaw */ 62 static u8 alaw_to_ulaw[256] = 63 { 64 0xab, 0x2b, 0xe3, 0x63, 0x8b, 0x0b, 0xc9, 0x49, 65 0xba, 0x3a, 0xf6, 0x76, 0x9b, 0x1b, 0xd7, 0x57, 66 0xa3, 0x23, 0xdd, 0x5d, 0x83, 0x03, 0xc1, 0x41, 67 0xb2, 0x32, 0xeb, 0x6b, 0x93, 0x13, 0xcf, 0x4f, 68 0xaf, 0x2f, 0xe7, 0x67, 0x8f, 0x0f, 0xcd, 0x4d, 69 0xbe, 0x3e, 0xfe, 0x7e, 0x9f, 0x1f, 0xdb, 0x5b, 70 0xa7, 0x27, 0xdf, 0x5f, 0x87, 0x07, 0xc5, 0x45, 71 0xb6, 0x36, 0xef, 0x6f, 0x97, 0x17, 0xd3, 0x53, 72 0xa9, 0x29, 0xe1, 0x61, 0x89, 0x09, 0xc7, 0x47, 73 0xb8, 0x38, 0xf2, 0x72, 0x99, 0x19, 0xd5, 0x55, 74 0xa1, 0x21, 0xdc, 0x5c, 0x81, 0x01, 0xbf, 0x3f, 75 0xb0, 0x30, 0xe9, 0x69, 0x91, 0x11, 0xce, 0x4e, 76 0xad, 0x2d, 0xe5, 0x65, 0x8d, 0x0d, 0xcb, 0x4b, 77 0xbc, 0x3c, 0xfa, 0x7a, 0x9d, 0x1d, 0xd9, 0x59, 78 0xa5, 0x25, 0xde, 0x5e, 0x85, 0x05, 0xc3, 0x43, 79 0xb4, 0x34, 0xed, 0x6d, 0x95, 0x15, 0xd1, 0x51, 80 0xac, 0x2c, 0xe4, 0x64, 0x8c, 0x0c, 0xca, 0x4a, 81 0xbb, 0x3b, 0xf8, 0x78, 0x9c, 0x1c, 0xd8, 0x58, 82 0xa4, 0x24, 0xde, 0x5e, 0x84, 0x04, 0xc2, 0x42, 83 0xb3, 0x33, 0xec, 0x6c, 0x94, 0x14, 0xd0, 0x50, 84 0xb0, 0x30, 0xe8, 0x68, 0x90, 0x10, 0xce, 0x4e, 85 0xbf, 0x3f, 0xfe, 0x7e, 0xa0, 0x20, 0xdc, 0x5c, 86 0xa8, 0x28, 0xe0, 0x60, 0x88, 0x08, 0xc6, 0x46, 87 0xb7, 0x37, 0xf0, 0x70, 0x98, 0x18, 0xd4, 0x54, 88 0xaa, 0x2a, 0xe2, 0x62, 0x8a, 0x0a, 0xc8, 0x48, 89 0xb9, 0x39, 0xf4, 0x74, 0x9a, 0x1a, 0xd6, 0x56, 90 0xa2, 0x22, 0xdd, 0x5d, 0x82, 0x02, 0xc0, 0x40, 91 0xb1, 0x31, 0xea, 0x6a, 0x92, 0x12, 0xcf, 0x4f, 92 0xae, 0x2e, 0xe6, 0x66, 0x8e, 0x0e, 0xcc, 0x4c, 93 0xbd, 0x3d, 0xfc, 0x7c, 0x9e, 0x1e, 0xda, 0x5a, 94 0xa6, 0x26, 0xdf, 0x5f, 0x86, 0x06, 0xc4, 0x44, 95 0xb5, 0x35, 0xee, 0x6e, 0x96, 0x16, 0xd2, 0x52 96 }; 97 98 /* ulaw -> alaw */ 99 static u8 ulaw_to_alaw[256] = 100 { 101 0xab, 0x55, 0xd5, 0x15, 0x95, 0x75, 0xf5, 0x35, 102 0xb5, 0x45, 0xc5, 0x05, 0x85, 0x65, 0xe5, 0x25, 103 0xa5, 0x5d, 0xdd, 0x1d, 0x9d, 0x7d, 0xfd, 0x3d, 104 0xbd, 0x4d, 0xcd, 0x0d, 0x8d, 0x6d, 0xed, 0x2d, 105 0xad, 0x51, 0xd1, 0x11, 0x91, 0x71, 0xf1, 0x31, 106 0xb1, 0x41, 0xc1, 0x01, 0x81, 0x61, 0xe1, 0x21, 107 0x59, 0xd9, 0x19, 0x99, 0x79, 0xf9, 0x39, 0xb9, 108 0x49, 0xc9, 0x09, 0x89, 0x69, 0xe9, 0x29, 0xa9, 109 0xd7, 0x17, 0x97, 0x77, 0xf7, 0x37, 0xb7, 0x47, 110 0xc7, 0x07, 0x87, 0x67, 0xe7, 0x27, 0xa7, 0xdf, 111 0x9f, 0x7f, 0xff, 0x3f, 0xbf, 0x4f, 0xcf, 0x0f, 112 0x8f, 0x6f, 0xef, 0x2f, 0x53, 0x13, 0x73, 0x33, 113 0xb3, 0x43, 0xc3, 0x03, 0x83, 0x63, 0xe3, 0x23, 114 0xa3, 0x5b, 0xdb, 0x1b, 0x9b, 0x7b, 0xfb, 0x3b, 115 0xbb, 0xbb, 0x4b, 0x4b, 0xcb, 0xcb, 0x0b, 0x0b, 116 0x8b, 0x8b, 0x6b, 0x6b, 0xeb, 0xeb, 0x2b, 0x2b, 117 0xab, 0x54, 0xd4, 0x14, 0x94, 0x74, 0xf4, 0x34, 118 0xb4, 0x44, 0xc4, 0x04, 0x84, 0x64, 0xe4, 0x24, 119 0xa4, 0x5c, 0xdc, 0x1c, 0x9c, 0x7c, 0xfc, 0x3c, 120 0xbc, 0x4c, 0xcc, 0x0c, 0x8c, 0x6c, 0xec, 0x2c, 121 0xac, 0x50, 0xd0, 0x10, 0x90, 0x70, 0xf0, 0x30, 122 0xb0, 0x40, 0xc0, 0x00, 0x80, 0x60, 0xe0, 0x20, 123 0x58, 0xd8, 0x18, 0x98, 0x78, 0xf8, 0x38, 0xb8, 124 0x48, 0xc8, 0x08, 0x88, 0x68, 0xe8, 0x28, 0xa8, 125 0xd6, 0x16, 0x96, 0x76, 0xf6, 0x36, 0xb6, 0x46, 126 0xc6, 0x06, 0x86, 0x66, 0xe6, 0x26, 0xa6, 0xde, 127 0x9e, 0x7e, 0xfe, 0x3e, 0xbe, 0x4e, 0xce, 0x0e, 128 0x8e, 0x6e, 0xee, 0x2e, 0x52, 0x12, 0x72, 0x32, 129 0xb2, 0x42, 0xc2, 0x02, 0x82, 0x62, 0xe2, 0x22, 130 0xa2, 0x5a, 0xda, 0x1a, 0x9a, 0x7a, 0xfa, 0x3a, 131 0xba, 0xba, 0x4a, 0x4a, 0xca, 0xca, 0x0a, 0x0a, 132 0x8a, 0x8a, 0x6a, 0x6a, 0xea, 0xea, 0x2a, 0x2a 133 }; 134 135 /* alaw -> 4bit compression */ 136 static u8 alaw_to_4bit[256] = { 137 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 138 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 139 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 140 0x0d, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 141 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 142 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 143 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 144 0x0d, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 145 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 146 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 147 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0d, 0x02, 148 0x0e, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 149 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 150 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 151 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 152 0x0d, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 153 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 154 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 155 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 156 0x0d, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 157 0x0e, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 158 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x01, 0x0a, 0x05, 159 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 160 0x0d, 0x02, 0x09, 0x07, 0x0f, 0x00, 0x0b, 0x04, 161 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 162 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 163 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 164 0x0d, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 165 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 166 0x0d, 0x02, 0x08, 0x07, 0x0f, 0x00, 0x0b, 0x04, 167 0x0e, 0x01, 0x0a, 0x05, 0x0f, 0x00, 0x0c, 0x03, 168 0x0d, 0x02, 0x09, 0x06, 0x0f, 0x00, 0x0b, 0x04, 169 }; 170 171 /* 4bit -> alaw decompression */ 172 static u8 _4bit_to_alaw[16] = { 173 0x5d, 0x51, 0xd9, 0xd7, 0x5f, 0x53, 0xa3, 0x4b, 174 0x2a, 0x3a, 0x22, 0x2e, 0x26, 0x56, 0x20, 0x2c, 175 }; 176 177 /* ulaw -> 4bit compression */ 178 static u8 ulaw_to_4bit[256] = { 179 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 180 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 181 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 182 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 183 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 184 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 185 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 186 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 187 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 188 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x04, 0x04, 189 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 190 0x04, 0x04, 0x04, 0x04, 0x05, 0x05, 0x05, 0x05, 191 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 192 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 193 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 194 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x08, 195 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 196 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 197 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 198 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 199 0x0f, 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 200 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 0x0e, 201 0x0e, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 202 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 203 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 204 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0b, 0x0b, 205 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 206 0x0b, 0x0b, 0x0b, 0x0b, 0x0a, 0x0a, 0x0a, 0x0a, 207 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 208 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 209 0x09, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 210 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 211 }; 212 213 /* 4bit -> ulaw decompression */ 214 static u8 _4bit_to_ulaw[16] = { 215 0x11, 0x21, 0x31, 0x40, 0x4e, 0x5c, 0x68, 0x71, 216 0xfe, 0xef, 0xe7, 0xdb, 0xcd, 0xbf, 0xaf, 0x9f, 217 }; 218 219 220 /* 221 * Compresses data to the result buffer 222 * The result size must be at least half of the input buffer. 223 * The number of samples also must be even! 224 */ 225 int 226 l1oip_law_to_4bit(u8 *data, int len, u8 *result, u32 *state) 227 { 228 int ii, i = 0, o = 0; 229 230 if (!len) 231 return 0; 232 233 /* send saved byte and first input byte */ 234 if (*state) { 235 *result++ = table_com[(((*state) << 8) & 0xff00) | (*data++)]; 236 len--; 237 o++; 238 } 239 240 ii = len >> 1; 241 242 while (i < ii) { 243 *result++ = table_com[(data[0]<<8) | (data[1])]; 244 data += 2; 245 i++; 246 o++; 247 } 248 249 /* if len has an odd number, we save byte for next call */ 250 if (len & 1) 251 *state = 0x100 + *data; 252 else 253 *state = 0; 254 255 return o; 256 } 257 258 /* Decompress data to the result buffer 259 * The result size must be the number of sample in packet. (2 * input data) 260 * The number of samples in the result are even! 261 */ 262 int 263 l1oip_4bit_to_law(u8 *data, int len, u8 *result) 264 { 265 int i = 0; 266 u16 r; 267 268 while (i < len) { 269 r = table_dec[*data++]; 270 *result++ = r >> 8; 271 *result++ = r; 272 i++; 273 } 274 275 return len << 1; 276 } 277 278 279 /* 280 * law conversion 281 */ 282 int 283 l1oip_alaw_to_ulaw(u8 *data, int len, u8 *result) 284 { 285 int i = 0; 286 287 while (i < len) { 288 *result++ = alaw_to_ulaw[*data++]; 289 i++; 290 } 291 292 return len; 293 } 294 295 int 296 l1oip_ulaw_to_alaw(u8 *data, int len, u8 *result) 297 { 298 int i = 0; 299 300 while (i < len) { 301 *result++ = ulaw_to_alaw[*data++]; 302 i++; 303 } 304 305 return len; 306 } 307 308 309 /* 310 * generate/free compression and decompression table 311 */ 312 void 313 l1oip_4bit_free(void) 314 { 315 vfree(table_dec); 316 vfree(table_com); 317 table_com = NULL; 318 table_dec = NULL; 319 } 320 321 int 322 l1oip_4bit_alloc(int ulaw) 323 { 324 int i1, i2, c, sample; 325 326 /* in case, it is called again */ 327 if (table_dec) 328 return 0; 329 330 /* alloc conversion tables */ 331 table_com = vzalloc(65536); 332 table_dec = vzalloc(512); 333 if (!table_com || !table_dec) { 334 l1oip_4bit_free(); 335 return -ENOMEM; 336 } 337 /* generate compression table */ 338 i1 = 0; 339 while (i1 < 256) { 340 if (ulaw) 341 c = ulaw_to_4bit[i1]; 342 else 343 c = alaw_to_4bit[i1]; 344 i2 = 0; 345 while (i2 < 256) { 346 table_com[(i1 << 8) | i2] |= (c << 4); 347 table_com[(i2 << 8) | i1] |= c; 348 i2++; 349 } 350 i1++; 351 } 352 353 /* generate decompression table */ 354 i1 = 0; 355 while (i1 < 16) { 356 if (ulaw) 357 sample = _4bit_to_ulaw[i1]; 358 else 359 sample = _4bit_to_alaw[i1]; 360 i2 = 0; 361 while (i2 < 16) { 362 table_dec[(i1 << 4) | i2] |= (sample << 8); 363 table_dec[(i2 << 4) | i1] |= sample; 364 i2++; 365 } 366 i1++; 367 } 368 369 return 0; 370 } 371