1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 /* 12 * arith_routinslogist.c 13 * 14 * This C file contains arithmetic encode and decode logistic 15 * 16 */ 17 18 #include "arith_routins.h" 19 20 /* Tables for piecewise linear cdf functions: y = k*x */ 21 22 /* x Points for function piecewise() in Q15 */ 23 static const int32_t kHistEdges[51] = { 24 -327680, -314573, -301466, -288359, -275252, -262144, -249037, -235930, -222823, -209716, 25 -196608, -183501, -170394, -157287, -144180, -131072, -117965, -104858, -91751, -78644, 26 -65536, -52429, -39322, -26215, -13108, 0, 13107, 26214, 39321, 52428, 27 65536, 78643, 91750, 104857, 117964, 131072, 144179, 157286, 170393, 183500, 28 196608, 209715, 222822, 235929, 249036, 262144, 275251, 288358, 301465, 314572, 29 327680 30 }; 31 32 33 /* k Points for function piecewise() in Q0 */ 34 static const uint16_t kCdfSlope[51] = { 35 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 36 5, 5, 13, 23, 47, 87, 154, 315, 700, 1088, 37 2471, 6064, 14221, 21463, 36634, 36924, 19750, 13270, 5806, 2312, 38 1095, 660, 316, 145, 86, 41, 32, 5, 5, 5, 39 5, 5, 5, 5, 5, 5, 5, 5, 5, 2, 40 0 41 }; 42 43 /* y Points for function piecewise() in Q0 */ 44 static const uint16_t kCdfLogistic[51] = { 45 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 46 20, 22, 24, 29, 38, 57, 92, 153, 279, 559, 47 994, 1983, 4408, 10097, 18682, 33336, 48105, 56005, 61313, 63636, 48 64560, 64998, 65262, 65389, 65447, 65481, 65497, 65510, 65512, 65514, 49 65516, 65518, 65520, 65522, 65524, 65526, 65528, 65530, 65532, 65534, 50 65535 51 }; 52 53 54 /**************************************************************************** 55 * WebRtcIsacfix_Piecewise(...) 56 * 57 * Piecewise linear function 58 * 59 * Input: 60 * - xinQ15 : input value x in Q15 61 * 62 * Return value : korresponding y-value in Q0 63 */ 64 65 66 static __inline uint16_t WebRtcIsacfix_Piecewise(int32_t xinQ15) { 67 int32_t ind; 68 int32_t qtmp1; 69 uint16_t qtmp2; 70 71 /* Find index for x-value */ 72 qtmp1 = WEBRTC_SPL_SAT(kHistEdges[50],xinQ15,kHistEdges[0]); 73 ind = WEBRTC_SPL_MUL(5, qtmp1 - kHistEdges[0]); 74 ind >>= 16; 75 76 /* Calculate corresponding y-value ans return*/ 77 qtmp1 = qtmp1 - kHistEdges[ind]; 78 qtmp2 = (uint16_t)WEBRTC_SPL_RSHIFT_U32( 79 WEBRTC_SPL_UMUL_32_16(qtmp1,kCdfSlope[ind]), 15); 80 return (kCdfLogistic[ind] + qtmp2); 81 } 82 83 /**************************************************************************** 84 * WebRtcIsacfix_EncLogisticMulti2(...) 85 * 86 * Arithmetic coding of spectrum. 87 * 88 * Input: 89 * - streamData : in-/output struct containing bitstream 90 * - dataQ7 : data vector in Q7 91 * - envQ8 : side info vector defining the width of the pdf 92 * in Q8 93 * - lenData : data vector length 94 * 95 * Return value : 0 if ok, 96 * <0 otherwise. 97 */ 98 int WebRtcIsacfix_EncLogisticMulti2(Bitstr_enc *streamData, 99 int16_t *dataQ7, 100 const uint16_t *envQ8, 101 const int16_t lenData) 102 { 103 uint32_t W_lower; 104 uint32_t W_upper; 105 uint16_t W_upper_LSB; 106 uint16_t W_upper_MSB; 107 uint16_t *streamPtr; 108 uint16_t *maxStreamPtr; 109 uint16_t *streamPtrCarry; 110 uint16_t negcarry; 111 uint32_t cdfLo; 112 uint32_t cdfHi; 113 int k; 114 115 /* point to beginning of stream buffer 116 * and set maximum streamPtr value */ 117 streamPtr = streamData->stream + streamData->stream_index; 118 maxStreamPtr = streamData->stream + STREAM_MAXW16_60MS - 1; 119 W_upper = streamData->W_upper; 120 121 for (k = 0; k < lenData; k++) 122 { 123 /* compute cdf_lower and cdf_upper by evaluating the 124 * WebRtcIsacfix_Piecewise linear cdf */ 125 cdfLo = WebRtcIsacfix_Piecewise(WEBRTC_SPL_MUL_16_U16(*dataQ7 - 64, *envQ8)); 126 cdfHi = WebRtcIsacfix_Piecewise(WEBRTC_SPL_MUL_16_U16(*dataQ7 + 64, *envQ8)); 127 128 /* test and clip if probability gets too small */ 129 while ((cdfLo + 1) >= cdfHi) { 130 /* clip */ 131 if (*dataQ7 > 0) { 132 *dataQ7 -= 128; 133 cdfHi = cdfLo; 134 cdfLo = WebRtcIsacfix_Piecewise( 135 WEBRTC_SPL_MUL_16_U16(*dataQ7 - 64, *envQ8)); 136 } else { 137 *dataQ7 += 128; 138 cdfLo = cdfHi; 139 cdfHi = WebRtcIsacfix_Piecewise( 140 WEBRTC_SPL_MUL_16_U16(*dataQ7 + 64, *envQ8)); 141 } 142 } 143 144 dataQ7++; 145 /* increment only once per 4 iterations */ 146 envQ8 += (k & 1) & (k >> 1); 147 148 149 /* update interval */ 150 W_upper_LSB = (uint16_t)W_upper; 151 W_upper_MSB = (uint16_t)WEBRTC_SPL_RSHIFT_U32(W_upper, 16); 152 W_lower = WEBRTC_SPL_UMUL_32_16(cdfLo, W_upper_MSB); 153 W_lower += (cdfLo * W_upper_LSB) >> 16; 154 W_upper = WEBRTC_SPL_UMUL_32_16(cdfHi, W_upper_MSB); 155 W_upper += (cdfHi * W_upper_LSB) >> 16; 156 157 /* shift interval such that it begins at zero */ 158 W_upper -= ++W_lower; 159 160 /* add integer to bitstream */ 161 streamData->streamval += W_lower; 162 163 /* handle carry */ 164 if (streamData->streamval < W_lower) 165 { 166 /* propagate carry */ 167 streamPtrCarry = streamPtr; 168 if (streamData->full == 0) { 169 negcarry = *streamPtrCarry; 170 negcarry += 0x0100; 171 *streamPtrCarry = negcarry; 172 while (!(negcarry)) 173 { 174 negcarry = *--streamPtrCarry; 175 negcarry++; 176 *streamPtrCarry = negcarry; 177 } 178 } else { 179 while (!(++(*--streamPtrCarry))); 180 } 181 } 182 183 /* renormalize interval, store most significant byte of streamval and update streamval 184 * W_upper < 2^24 */ 185 while ( !(W_upper & 0xFF000000) ) 186 { 187 W_upper <<= 8; 188 if (streamData->full == 0) { 189 *streamPtr++ += (uint16_t) WEBRTC_SPL_RSHIFT_U32( 190 streamData->streamval, 24); 191 streamData->full = 1; 192 } else { 193 *streamPtr = (uint16_t)((streamData->streamval >> 24) << 8); 194 streamData->full = 0; 195 } 196 197 if( streamPtr > maxStreamPtr ) 198 return -ISAC_DISALLOWED_BITSTREAM_LENGTH; 199 200 streamData->streamval <<= 8; 201 } 202 } 203 204 /* calculate new stream_index */ 205 streamData->stream_index = streamPtr - streamData->stream; 206 streamData->W_upper = W_upper; 207 208 return 0; 209 } 210 211 212 /**************************************************************************** 213 * WebRtcIsacfix_DecLogisticMulti2(...) 214 * 215 * Arithmetic decoding of spectrum. 216 * 217 * Input: 218 * - streamData : in-/output struct containing bitstream 219 * - envQ8 : side info vector defining the width of the pdf 220 * in Q8 221 * - lenData : data vector length 222 * 223 * Input/Output: 224 * - dataQ7 : input: dither vector, output: data vector 225 * 226 * Return value : number of bytes in the stream so far 227 * -1 if error detected 228 */ 229 int WebRtcIsacfix_DecLogisticMulti2(int16_t *dataQ7, 230 Bitstr_dec *streamData, 231 const int32_t *envQ8, 232 const int16_t lenData) 233 { 234 uint32_t W_lower; 235 uint32_t W_upper; 236 uint32_t W_tmp; 237 uint16_t W_upper_LSB; 238 uint16_t W_upper_MSB; 239 uint32_t streamVal; 240 uint16_t cdfTmp; 241 int32_t res; 242 int32_t inSqrt; 243 int32_t newRes; 244 const uint16_t *streamPtr; 245 int16_t candQ7; 246 int16_t envCount; 247 uint16_t tmpARSpecQ8 = 0; 248 int k, i; 249 int offset = 0; 250 251 /* point to beginning of stream buffer */ 252 streamPtr = streamData->stream + streamData->stream_index; 253 W_upper = streamData->W_upper; 254 255 /* Check if it is first time decoder is called for this stream */ 256 if (streamData->stream_index == 0) 257 { 258 /* read first word from bytestream */ 259 streamVal = (uint32_t)(*streamPtr++) << 16; 260 streamVal |= *streamPtr++; 261 262 } else { 263 streamVal = streamData->streamval; 264 } 265 266 267 res = 1 << (WebRtcSpl_GetSizeInBits(envQ8[0]) >> 1); 268 envCount = 0; 269 270 /* code assumes lenData%4 == 0 */ 271 for (k = 0; k < lenData; k += 4) 272 { 273 int k4; 274 275 /* convert to magnitude spectrum, by doing square-roots (modified from SPLIB) */ 276 inSqrt = envQ8[envCount]; 277 i = 10; 278 279 /* For safty reasons */ 280 if (inSqrt < 0) 281 inSqrt=-inSqrt; 282 283 newRes = (inSqrt / res + res) >> 1; 284 do 285 { 286 res = newRes; 287 newRes = (inSqrt / res + res) >> 1; 288 } while (newRes != res && i-- > 0); 289 290 tmpARSpecQ8 = (uint16_t)newRes; 291 292 for(k4 = 0; k4 < 4; k4++) 293 { 294 /* find the integer *data for which streamVal lies in [W_lower+1, W_upper] */ 295 W_upper_LSB = (uint16_t) (W_upper & 0x0000FFFF); 296 W_upper_MSB = (uint16_t) WEBRTC_SPL_RSHIFT_U32(W_upper, 16); 297 298 /* find first candidate by inverting the logistic cdf 299 * Input dither value collected from io-stream */ 300 candQ7 = - *dataQ7 + 64; 301 cdfTmp = WebRtcIsacfix_Piecewise(WEBRTC_SPL_MUL_16_U16(candQ7, tmpARSpecQ8)); 302 303 W_tmp = (uint32_t)cdfTmp * W_upper_MSB; 304 W_tmp += ((uint32_t)cdfTmp * (uint32_t)W_upper_LSB) >> 16; 305 306 if (streamVal > W_tmp) 307 { 308 W_lower = W_tmp; 309 candQ7 += 128; 310 cdfTmp = WebRtcIsacfix_Piecewise(WEBRTC_SPL_MUL_16_U16(candQ7, tmpARSpecQ8)); 311 312 W_tmp = (uint32_t)cdfTmp * W_upper_MSB; 313 W_tmp += ((uint32_t)cdfTmp * (uint32_t)W_upper_LSB) >> 16; 314 315 while (streamVal > W_tmp) 316 { 317 W_lower = W_tmp; 318 candQ7 += 128; 319 cdfTmp = WebRtcIsacfix_Piecewise( 320 WEBRTC_SPL_MUL_16_U16(candQ7, tmpARSpecQ8)); 321 322 W_tmp = (uint32_t)cdfTmp * W_upper_MSB; 323 W_tmp += ((uint32_t)cdfTmp * (uint32_t)W_upper_LSB) >> 16; 324 325 /* error check */ 326 if (W_lower == W_tmp) { 327 return -1; 328 } 329 } 330 W_upper = W_tmp; 331 332 /* Output value put in dataQ7: another sample decoded */ 333 *dataQ7 = candQ7 - 64; 334 } 335 else 336 { 337 W_upper = W_tmp; 338 candQ7 -= 128; 339 cdfTmp = WebRtcIsacfix_Piecewise(WEBRTC_SPL_MUL_16_U16(candQ7, tmpARSpecQ8)); 340 341 W_tmp = (uint32_t)cdfTmp * W_upper_MSB; 342 W_tmp += ((uint32_t)cdfTmp * (uint32_t)W_upper_LSB) >> 16; 343 344 while ( !(streamVal > W_tmp) ) 345 { 346 W_upper = W_tmp; 347 candQ7 -= 128; 348 cdfTmp = WebRtcIsacfix_Piecewise( 349 WEBRTC_SPL_MUL_16_U16(candQ7, tmpARSpecQ8)); 350 351 W_tmp = (uint32_t)cdfTmp * W_upper_MSB; 352 W_tmp += ((uint32_t)cdfTmp * (uint32_t)W_upper_LSB) >> 16; 353 354 /* error check */ 355 if (W_upper == W_tmp){ 356 return -1; 357 } 358 } 359 W_lower = W_tmp; 360 361 /* Output value put in dataQ7: another sample decoded */ 362 *dataQ7 = candQ7 + 64; 363 } 364 365 dataQ7++; 366 367 /* shift interval to start at zero */ 368 W_upper -= ++W_lower; 369 370 /* add integer to bitstream */ 371 streamVal -= W_lower; 372 373 /* renormalize interval and update streamVal 374 * W_upper < 2^24 */ 375 while ( !(W_upper & 0xFF000000) ) 376 { 377 if (streamPtr < streamData->stream + streamData->stream_size) { 378 /* read next byte from stream */ 379 if (streamData->full == 0) { 380 streamVal = (streamVal << 8) | (*streamPtr++ & 0x00FF); 381 streamData->full = 1; 382 } else { 383 streamVal = (streamVal << 8) | (*streamPtr >> 8); 384 streamData->full = 0; 385 } 386 } else { 387 /* Intending to read outside the stream. This can happen for the last 388 * two or three bytes. It is how the algorithm is implemented. Do 389 * not read from the bit stream and insert zeros instead. */ 390 streamVal <<= 8; 391 if (streamData->full == 0) { 392 offset++; // We would have incremented the pointer in this case. 393 streamData->full = 1; 394 } else { 395 streamData->full = 0; 396 } 397 } 398 W_upper <<= 8; 399 } 400 } 401 envCount++; 402 } 403 404 streamData->stream_index = streamPtr + offset - streamData->stream; 405 streamData->W_upper = W_upper; 406 streamData->streamval = streamVal; 407 408 /* find number of bytes in original stream (determined by current interval width) */ 409 if ( W_upper > 0x01FFFFFF ) 410 return (streamData->stream_index*2 - 3 + !streamData->full); 411 else 412 return (streamData->stream_index*2 - 2 + !streamData->full); 413 } 414
