Harish Mahendrakar | 0d8951c | 2014-05-16 10:31:13 -0700 | [diff] [blame] | 1 | /****************************************************************************** |
| 2 | * |
| 3 | * Copyright (C) 2012 Ittiam Systems Pvt Ltd, Bangalore |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at: |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | ******************************************************************************/ |
| 18 | /** |
| 19 | ****************************************************************************** |
| 20 | * @file ihevcd_cabac.c |
| 21 | * |
| 22 | * @brief |
| 23 | * This file contains function definitions related to CABAC parsing |
| 24 | * |
| 25 | * @author |
| 26 | * Ittiam |
| 27 | * |
| 28 | * |
| 29 | * List of Functions |
| 30 | * |
| 31 | * ihevcd_cabac_init() |
| 32 | * ihevcd_cabac_decode_bin() |
| 33 | * ihevcd_cabac_decode_bypass_bin() |
| 34 | * ihevcd_cabac_decode_bypass_bins_tunary() |
| 35 | * ihevcd_cabac_decode_terminate() |
| 36 | * ihevcd_cabac_decode_bin_tunary() |
| 37 | * ihevcd_cabac_decode_bypass_bins() |
| 38 | * ihevcd_cabac_decode_bypass_bins_egk() |
| 39 | * ihevcd_cabac_decode_trunc_rice() |
| 40 | * ihevcd_cabac_flush() |
| 41 | * |
| 42 | ****************************************************************************** |
| 43 | */ |
| 44 | |
| 45 | /*****************************************************************************/ |
| 46 | /* File Includes */ |
| 47 | /*****************************************************************************/ |
| 48 | #include <stdio.h> |
| 49 | #include <stddef.h> |
| 50 | #include <assert.h> |
| 51 | #include <stdlib.h> |
| 52 | #include <string.h> |
| 53 | |
| 54 | #include "ihevc_typedefs.h" |
| 55 | #include "iv.h" |
| 56 | #include "ivd.h" |
| 57 | #include "ihevcd_cxa.h" |
| 58 | |
| 59 | |
| 60 | #include "ihevc_debug.h" |
| 61 | #include "ihevc_macros.h" |
| 62 | #include "ihevc_platform_macros.h" |
| 63 | #include "ihevc_cabac_tables.h" |
| 64 | #include "ihevc_defs.h" |
| 65 | #include "ihevc_structs.h" |
| 66 | #include "ihevc_cabac_tables.h" |
| 67 | |
| 68 | |
| 69 | #include "ihevcd_defs.h" |
| 70 | #include "ihevcd_function_selector.h" |
| 71 | #include "ihevcd_structs.h" |
| 72 | #include "ihevcd_error.h" |
| 73 | #include "ihevcd_bitstream.h" |
| 74 | #include "ihevcd_cabac.h" |
| 75 | #include "ihevcd_trace.h" |
| 76 | |
| 77 | #ifdef TRACE |
| 78 | extern trace_t g_trace; |
| 79 | #endif |
| 80 | #if DEBUG_CABAC_RANGE_OFST |
| 81 | #if FULLRANGE |
| 82 | #define DEBUG_RANGE_OFST(str, m_range, m_ofst ) \ |
| 83 | {\ |
| 84 | UWORD32 m_clz, m_range_shift, m_ofst_shift; \ |
| 85 | m_clz = CLZ(m_range); \ |
| 86 | m_clz -= (32 - RANGE_NUMBITS); \ |
| 87 | m_range_shift = m_range << m_clz; \ |
| 88 | m_range_shift = m_range_shift >> RANGE_SHIFT; \ |
| 89 | m_ofst_shift = m_ofst << m_clz; \ |
| 90 | m_ofst_shift = m_ofst_shift >> RANGE_SHIFT; \ |
| 91 | fprintf( g_trace.fp, "%-40s R: %3d O: %3d\n", str, m_range_shift, m_ofst_shift); \ |
| 92 | } |
| 93 | |
| 94 | #else |
| 95 | #define DEBUG_RANGE_OFST(str, m_range, m_ofst) \ |
| 96 | fprintf( g_trace.fp, "%-40s R: %3d O: %3d\n", str, m_range, m_ofst); |
| 97 | #endif |
| 98 | #else |
| 99 | #define DEBUG_RANGE_OFST(str, m_range, m_ofst ) |
| 100 | #endif |
| 101 | /*****************************************************************************/ |
| 102 | /* Function Definitions */ |
| 103 | /*****************************************************************************/ |
| 104 | |
| 105 | /** |
| 106 | ****************************************************************************** |
| 107 | * |
| 108 | * @brief Initializes the decoder cabac engine |
| 109 | * |
| 110 | * @par Description |
| 111 | * This routine needs to be called at start of slice/frame decode |
| 112 | * |
| 113 | * @param[in,out] ps_cabac_ctxt |
| 114 | * pointer to cabac context (handle) |
| 115 | * |
| 116 | * @param[in] ps_bitstrm |
| 117 | * pointer to bitstream context (handle) |
| 118 | * |
| 119 | * @param[in] qp |
| 120 | * current slice Qp |
| 121 | * |
| 122 | * @param[in] cabac_init_idc |
| 123 | * current slice init idc (range [0 - 2]) |
| 124 | * |
| 125 | * @param[in] pu1_init_ctxt |
| 126 | * Init cabac context to be used (range [0 - 2]) |
| 127 | * |
| 128 | * @return success or failure error code |
| 129 | * |
| 130 | ****************************************************************************** |
| 131 | */ |
| 132 | IHEVCD_ERROR_T ihevcd_cabac_init(cab_ctxt_t *ps_cabac, |
| 133 | bitstrm_t *ps_bitstrm, |
| 134 | WORD32 qp, |
| 135 | WORD32 cabac_init_idc, |
| 136 | const UWORD8 *pu1_init_ctxt) |
| 137 | { |
| 138 | /* Sanity checks */ |
| 139 | ASSERT(ps_cabac != NULL); |
| 140 | ASSERT(ps_bitstrm != NULL); |
| 141 | ASSERT((qp >= 0) && (qp < 52)); |
| 142 | ASSERT((cabac_init_idc >= 0) && (cabac_init_idc < 3)); |
| 143 | UNUSED(qp); |
| 144 | UNUSED(cabac_init_idc); |
| 145 | /* CABAC engine uses 32 bit range instead of 9 bits as specified by |
| 146 | * the spec. This is done to reduce number of renormalizations |
| 147 | */ |
| 148 | /* cabac engine initialization */ |
| 149 | #if FULLRANGE |
| 150 | ps_cabac->u4_range = (UWORD32)510 << RANGE_SHIFT; |
| 151 | BITS_GET(ps_cabac->u4_ofst, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 152 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, (9 + RANGE_SHIFT)); |
| 153 | |
| 154 | #else |
| 155 | ps_cabac->u4_range = (UWORD32)510; |
| 156 | BITS_GET(ps_cabac->u4_ofst, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 157 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, 9); |
| 158 | |
| 159 | #endif |
| 160 | |
| 161 | /* cabac context initialization based on init idc and slice qp */ |
| 162 | memcpy(ps_cabac->au1_ctxt_models, |
| 163 | pu1_init_ctxt, |
| 164 | IHEVC_CAB_CTXT_END); |
| 165 | DEBUG_RANGE_OFST("init", ps_cabac->u4_range, ps_cabac->u4_ofst); |
| 166 | return ((IHEVCD_ERROR_T)IHEVCD_SUCCESS); |
| 167 | } |
| 168 | |
| 169 | IHEVCD_ERROR_T ihevcd_cabac_reset(cab_ctxt_t *ps_cabac, |
| 170 | bitstrm_t *ps_bitstrm) |
| 171 | { |
| 172 | /* Sanity checks */ |
| 173 | ASSERT(ps_cabac != NULL); |
| 174 | ASSERT(ps_bitstrm != NULL); |
| 175 | |
| 176 | /* CABAC engine uses 32 bit range instead of 9 bits as specified by |
| 177 | * the spec. This is done to reduce number of renormalizations |
| 178 | */ |
| 179 | /* cabac engine initialization */ |
| 180 | #if FULLRANGE |
| 181 | ps_cabac->u4_range = (UWORD32)510 << RANGE_SHIFT; |
| 182 | BITS_GET(ps_cabac->u4_ofst, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 183 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, (9 + RANGE_SHIFT)); |
| 184 | |
| 185 | #else |
| 186 | ps_cabac->u4_range = (UWORD32)510; |
| 187 | BITS_GET(ps_cabac->u4_ofst, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 188 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, 9); |
| 189 | |
| 190 | #endif |
| 191 | |
| 192 | return ((IHEVCD_ERROR_T)IHEVCD_SUCCESS); |
| 193 | } |
| 194 | |
| 195 | /** |
| 196 | ****************************************************************************** |
| 197 | * |
| 198 | * @brief Decodes a bin based on probablilty and mps packed context model |
| 199 | * |
| 200 | * @par Description |
| 201 | * Decodes a bin as per Section : 9.3.3.2.1 and calls renormalization if required |
| 202 | * as per section 9.3.3.2.2 |
| 203 | * 1. Apart from decoding bin, context model is updated as per state transition |
| 204 | * 2. Range and Low renormalization is done based on bin and original state |
| 205 | * 3. After renorm bistream is updated (if required) |
| 206 | * |
| 207 | * @param[in,out] ps_cabac |
| 208 | * pointer to cabac context (handle) |
| 209 | * |
| 210 | * @param[in] ctxt_index |
| 211 | * index of cabac context model containing pState[bits6-1] | MPS[bit0] |
| 212 | * |
| 213 | * @param[in] ps_bitstrm |
| 214 | * Bitstream context |
| 215 | * |
| 216 | * @return bin(boolean) to be decoded |
| 217 | * |
| 218 | ****************************************************************************** |
| 219 | */ |
| 220 | UWORD32 ihevcd_cabac_decode_bin(cab_ctxt_t *ps_cabac, |
| 221 | bitstrm_t *ps_bitstrm, |
| 222 | WORD32 ctxt_index |
| 223 | |
| 224 | ) |
| 225 | { |
| 226 | UWORD32 u4_range = ps_cabac->u4_range; |
| 227 | UWORD32 u4_ofst = ps_cabac->u4_ofst; |
| 228 | UWORD32 u4_rlps; |
| 229 | UWORD32 u4_bin; |
| 230 | UWORD8 *pu1_ctxt_model = &ps_cabac->au1_ctxt_models[ctxt_index]; |
| 231 | WORD32 state_mps = *pu1_ctxt_model; |
| 232 | #if FULLRANGE |
| 233 | WORD32 clz; |
| 234 | #endif |
| 235 | UWORD32 u4_qnt_range; |
| 236 | |
| 237 | /* Sanity checks */ |
| 238 | ASSERT(u4_range >= 256); |
| 239 | ASSERT((ctxt_index >= 0) && (ctxt_index < IHEVC_CAB_CTXT_END)); |
| 240 | ASSERT(state_mps < 128); |
| 241 | #if FULLRANGE |
| 242 | clz = CLZ(u4_range); |
| 243 | clz -= (32 - RANGE_NUMBITS); |
| 244 | u4_qnt_range = u4_range << clz; |
| 245 | u4_qnt_range = (u4_qnt_range >> (RANGE_SHIFT + 6)) & 0x3; |
| 246 | #else |
| 247 | u4_qnt_range = (u4_range >> 6) & 0x3; |
| 248 | #endif |
| 249 | /* Get the lps range from LUT based on quantized range and state */ |
| 250 | u4_rlps = gau1_ihevc_cabac_rlps[state_mps >> 1][u4_qnt_range]; |
| 251 | #if FULLRANGE |
| 252 | u4_rlps = u4_rlps << (RANGE_SHIFT - clz); |
| 253 | #endif |
| 254 | u4_range -= u4_rlps; |
| 255 | |
| 256 | u4_bin = state_mps & 1; |
| 257 | |
| 258 | if(u4_ofst >= u4_range) |
| 259 | { |
| 260 | u4_bin = 1 - u4_bin; |
| 261 | u4_ofst -= u4_range; |
| 262 | u4_range = u4_rlps; |
| 263 | } |
| 264 | |
| 265 | *pu1_ctxt_model = gau1_ihevc_next_state[(state_mps << 1) | u4_bin]; |
| 266 | |
| 267 | /*****************************************************************/ |
| 268 | /* Re-normalization; calculate bits generated based on range(R) */ |
| 269 | /*****************************************************************/ |
| 270 | if(u4_range < (1 << 8)) |
| 271 | { |
| 272 | UWORD32 u4_bits; |
| 273 | WORD32 numbits; |
| 274 | numbits = CLZ(u4_range); |
| 275 | numbits -= (32 - RANGE_NUMBITS); |
| 276 | #if !FULLRANGE |
| 277 | numbits -= RANGE_SHIFT; |
| 278 | #endif |
| 279 | BITS_GET(u4_bits, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 280 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, numbits); |
| 281 | |
| 282 | u4_ofst <<= numbits; |
| 283 | u4_ofst |= u4_bits; |
| 284 | u4_range <<= numbits; |
| 285 | |
| 286 | } |
| 287 | /* Update the cabac context */ |
| 288 | ps_cabac->u4_range = u4_range; |
| 289 | ps_cabac->u4_ofst = u4_ofst; |
| 290 | DEBUG_RANGE_OFST("bin", ps_cabac->u4_range, ps_cabac->u4_ofst); |
| 291 | |
| 292 | return (u4_bin); |
| 293 | |
| 294 | |
| 295 | } |
| 296 | |
| 297 | /** |
| 298 | ****************************************************************************** |
| 299 | * |
| 300 | * @brief Decodes a bypass bin (equi-probable 0 / 1) |
| 301 | * |
| 302 | * @par Description |
| 303 | * Decodes a bypss bin as per Section : 9.3.3.2.3 |
| 304 | * |
| 305 | * @param[in,out] ps_cabac |
| 306 | * pointer to cabac context (handle) |
| 307 | * |
| 308 | * @param[in] ps_bitstrm |
| 309 | * Bitstream context |
| 310 | * |
| 311 | * @return Decoded bypass bin |
| 312 | * |
| 313 | ****************************************************************************** |
| 314 | */ |
| 315 | UWORD32 ihevcd_cabac_decode_bypass_bin(cab_ctxt_t *ps_cabac, |
| 316 | bitstrm_t *ps_bitstrm) |
| 317 | { |
| 318 | |
| 319 | UWORD32 u4_bin; |
| 320 | UWORD32 u4_range = ps_cabac->u4_range; |
| 321 | UWORD32 u4_ofst = ps_cabac->u4_ofst; |
| 322 | UWORD32 u4_bits; |
| 323 | |
| 324 | /* Sanity checks */ |
| 325 | ASSERT(u4_range >= 256); |
| 326 | |
| 327 | BIT_GET(u4_bits, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 328 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word); |
| 329 | |
| 330 | u4_ofst <<= 1; |
| 331 | u4_ofst |= u4_bits; |
| 332 | |
| 333 | u4_bin = 0; |
| 334 | if(u4_ofst >= u4_range) |
| 335 | { |
| 336 | u4_bin = 1; |
| 337 | u4_ofst -= u4_range; |
| 338 | } |
| 339 | |
| 340 | /* Update the cabac context */ |
| 341 | ps_cabac->u4_ofst = u4_ofst; |
| 342 | DEBUG_RANGE_OFST("bypass end", ps_cabac->u4_range, ps_cabac->u4_ofst); |
| 343 | return (u4_bin); |
| 344 | } |
| 345 | |
| 346 | /** |
| 347 | ****************************************************************************** |
| 348 | * |
| 349 | * @brief Decodes a terminate bin (1:terminate 0:do not terminate) |
| 350 | * |
| 351 | * @par Description |
| 352 | * Decodes a terminate bin to be called for end_of_slice_flag and pcm_flag |
| 353 | * as per Section : 9.3.3.2.4 |
| 354 | * |
| 355 | * @param[in,out] ps_cabac |
| 356 | * pointer to cabac context (handle) |
| 357 | * |
| 358 | * @param[in] ps_bitstrm |
| 359 | * Bitstream context |
| 360 | * |
| 361 | * @return Decoded Bin to indicate whether to terminate or not |
| 362 | * |
| 363 | ****************************************************************************** |
| 364 | */ |
| 365 | UWORD32 ihevcd_cabac_decode_terminate(cab_ctxt_t *ps_cabac, |
| 366 | bitstrm_t *ps_bitstrm) |
| 367 | { |
| 368 | UWORD32 u4_range = ps_cabac->u4_range; |
| 369 | UWORD32 u4_ofst = ps_cabac->u4_ofst; |
| 370 | UWORD32 u4_bin; |
| 371 | #if FULLRANGE |
| 372 | WORD32 clz; |
| 373 | #endif |
| 374 | /* Sanity checks */ |
| 375 | ASSERT(u4_range >= 256); |
| 376 | #if FULLRANGE |
| 377 | clz = CLZ(u4_range); |
| 378 | clz -= (32 - RANGE_NUMBITS); |
| 379 | u4_range -= 2 << (RANGE_SHIFT - clz); |
| 380 | #else |
| 381 | u4_range -= 2; |
| 382 | #endif |
| 383 | |
| 384 | if(u4_ofst >= u4_range) |
| 385 | { |
| 386 | u4_bin = 1; |
| 387 | |
| 388 | #if FULLRANGE |
| 389 | /* In case of FULLRANGE extra bits read earlier need to pushed back to the bitstream */ |
| 390 | { |
| 391 | WORD32 clz; |
| 392 | WORD32 numbits; |
| 393 | clz = CLZ(ps_cabac->u4_range); |
| 394 | |
| 395 | numbits = (32 - clz); |
| 396 | numbits -= 9; |
| 397 | |
| 398 | ihevcd_bits_seek(ps_bitstrm, -numbits); |
| 399 | } |
| 400 | #endif |
| 401 | |
| 402 | } |
| 403 | else |
| 404 | { |
| 405 | u4_bin = 0; |
| 406 | } |
| 407 | if(0 == u4_bin) |
| 408 | { |
| 409 | UWORD32 u4_bits; |
| 410 | WORD32 numbits; |
| 411 | numbits = CLZ(u4_range); |
| 412 | numbits -= (32 - RANGE_NUMBITS); |
| 413 | #if !FULLRANGE |
| 414 | numbits -= RANGE_SHIFT; |
| 415 | #endif |
| 416 | /* Renormalize if required */ |
| 417 | if(numbits) |
| 418 | { |
| 419 | BITS_GET(u4_bits, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 420 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, numbits); |
| 421 | |
| 422 | u4_ofst <<= numbits; |
| 423 | u4_ofst |= u4_bits; |
| 424 | u4_range <<= numbits; |
| 425 | } |
| 426 | } |
| 427 | /* bits to be inserted in the bitstream */ |
| 428 | ps_cabac->u4_range = u4_range; |
| 429 | ps_cabac->u4_ofst = u4_ofst; |
| 430 | DEBUG_RANGE_OFST("term", ps_cabac->u4_range, ps_cabac->u4_ofst); |
| 431 | |
| 432 | return (u4_bin); |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | ****************************************************************************** |
| 437 | * |
| 438 | * @brief Decodes a bypass bin (equi-probable 0 / 1) |
| 439 | * |
| 440 | * @par Description |
| 441 | * Decodes a bypss bin as per Section : 9.3.3.2.3 |
| 442 | * |
| 443 | * @param[in,out] ps_cabac |
| 444 | * pointer to cabac context (handle) |
| 445 | * |
| 446 | * @param[in] ps_bitstrm |
| 447 | * Bitstream context |
| 448 | * |
| 449 | * @param[in] numbins |
| 450 | * Number of bins to decoded |
| 451 | * |
| 452 | * @return Decoded bypass bin |
| 453 | * |
| 454 | * @remarks Tested only for numbins less than 17 |
| 455 | * |
| 456 | ****************************************************************************** |
| 457 | */ |
| 458 | |
| 459 | UWORD32 ihevcd_cabac_decode_bypass_bins(cab_ctxt_t *ps_cabac, |
| 460 | bitstrm_t *ps_bitstrm, |
| 461 | WORD32 numbins) |
| 462 | { |
| 463 | UWORD32 u4_bins; |
| 464 | |
| 465 | |
| 466 | UWORD32 u4_range = ps_cabac->u4_range; |
| 467 | UWORD32 u4_ofst = ps_cabac->u4_ofst; |
| 468 | UWORD32 u4_bits; |
| 469 | ASSERT(u4_range >= 256); |
| 470 | ASSERT(numbins > 0); |
| 471 | |
| 472 | /* Sanity checks */ |
| 473 | ASSERT(numbins < 17); |
| 474 | |
| 475 | u4_bins = 0; |
| 476 | |
| 477 | BITS_GET(u4_bits, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 478 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, numbins); |
| 479 | |
| 480 | do |
| 481 | { |
| 482 | UWORD32 u4_bit; |
| 483 | numbins--; |
| 484 | u4_bit = (u4_bits >> numbins) & 1; |
| 485 | u4_ofst <<= 1; |
| 486 | u4_ofst |= u4_bit; |
| 487 | |
| 488 | u4_bins <<= 1; |
| 489 | if(u4_ofst >= u4_range) |
| 490 | { |
| 491 | u4_bins += 1; |
| 492 | u4_ofst -= u4_range; |
| 493 | } |
| 494 | }while(numbins); |
| 495 | |
| 496 | /* Update the cabac context */ |
| 497 | ps_cabac->u4_ofst = u4_ofst; |
| 498 | DEBUG_RANGE_OFST("bypass", ps_cabac->u4_range, ps_cabac->u4_ofst); |
| 499 | return (u4_bins); |
| 500 | } |
| 501 | |
| 502 | /** |
| 503 | ****************************************************************************** |
| 504 | * |
| 505 | * @brief Decodes a truncated unary symbol associated with context model(s) |
| 506 | * |
| 507 | * @par Description |
| 508 | * Decodes symbols coded with TUnary binarization as per sec 9.3.2.2 |
| 509 | * This is used for computing symbols like qp_delta, |
| 510 | * last_sig_coeff_prefix_x, last_sig_coeff_prefix_y. |
| 511 | * |
| 512 | * The context models associated with each bin is computed as : |
| 513 | * current bin context = "base context idx" + (bin_idx >> shift) |
| 514 | * where |
| 515 | * 1. "base context idx" is the base index for the syntax element |
| 516 | * 2. "bin_idx" is the current bin index of the unary code |
| 517 | * 3. "shift" is the shift factor associated with this syntax element |
| 518 | * |
| 519 | * @param[in,out] ps_cabac |
| 520 | * pointer to cabac context (handle) |
| 521 | * |
| 522 | * @param[in] ps_bitstrm |
| 523 | * Bitstream context |
| 524 | * |
| 525 | * @param[in] c_max |
| 526 | * maximum value of sym (required for tunary binarization) |
| 527 | * |
| 528 | * @param[in] ctxt_index |
| 529 | * base context model index for this syntax element |
| 530 | * |
| 531 | * @param[in] ctxt_shift |
| 532 | * shift factor for context increments associated with this syntax element |
| 533 | * |
| 534 | * @param[in] ctxt_inc_max |
| 535 | * max value of context increment beyond which all bins will use same ctxt |
| 536 | * |
| 537 | * @return syntax element decoded |
| 538 | * |
| 539 | ****************************************************************************** |
| 540 | */ |
| 541 | UWORD32 ihevcd_cabac_decode_bins_tunary(cab_ctxt_t *ps_cabac, |
| 542 | bitstrm_t *ps_bitstrm, |
| 543 | WORD32 c_max, |
| 544 | WORD32 ctxt_index, |
| 545 | WORD32 ctxt_shift, |
| 546 | WORD32 ctxt_inc_max) |
| 547 | { |
| 548 | UWORD32 u4_sym; |
| 549 | WORD32 bin; |
| 550 | |
| 551 | /* Sanity checks */ |
| 552 | ASSERT(c_max > 0); |
| 553 | ASSERT((ctxt_index >= 0) && (ctxt_index < IHEVC_CAB_CTXT_END)); |
| 554 | ASSERT((ctxt_index + (c_max >> ctxt_shift)) < IHEVC_CAB_CTXT_END); |
| 555 | |
| 556 | u4_sym = 0; |
| 557 | do |
| 558 | { |
| 559 | WORD32 bin_index; |
Harish Mahendrakar | 707042f | 2014-06-04 10:31:48 -0700 | [diff] [blame] | 560 | bin_index = ctxt_index + MIN((u4_sym >> ctxt_shift), (UWORD32)ctxt_inc_max); |
Harish Mahendrakar | 0d8951c | 2014-05-16 10:31:13 -0700 | [diff] [blame] | 561 | IHEVCD_CABAC_DECODE_BIN(bin, ps_cabac, ps_bitstrm, bin_index); |
| 562 | u4_sym++; |
| 563 | }while(((WORD32)u4_sym < c_max) && bin); |
| 564 | |
| 565 | u4_sym = u4_sym - 1 + bin; |
| 566 | |
| 567 | return (u4_sym); |
| 568 | } |
| 569 | |
| 570 | /** |
| 571 | ****************************************************************************** |
| 572 | * |
| 573 | * @brief Decodes a syntax element as truncated unary bypass bins |
| 574 | * |
| 575 | * @par Description |
| 576 | * Decodes symbols coded with TUnary binarization as per sec 9.3.2.2 |
| 577 | * These symbols are coded as bypass bins |
| 578 | * This is used for computing symbols like merge_idx, |
| 579 | * mpm_idx etc |
| 580 | * |
| 581 | * @param[in,out]ps_cabac |
| 582 | * pointer to cabac context (handle) |
| 583 | * |
| 584 | * @param[in] ps_bitstrm |
| 585 | * Bitstream context |
| 586 | * |
| 587 | * @param[in] c_max |
| 588 | * maximum value of sym (required for tunary binarization) |
| 589 | * |
| 590 | * @return syntax element decoded |
| 591 | * |
| 592 | ****************************************************************************** |
| 593 | */ |
| 594 | UWORD32 ihevcd_cabac_decode_bypass_bins_tunary(cab_ctxt_t *ps_cabac, |
| 595 | bitstrm_t *ps_bitstrm, |
| 596 | WORD32 c_max) |
| 597 | { |
| 598 | |
| 599 | UWORD32 u4_sym; |
| 600 | WORD32 bin; |
| 601 | UWORD32 u4_ofst = ps_cabac->u4_ofst; |
| 602 | UWORD32 u4_range = ps_cabac->u4_range; |
| 603 | UWORD32 u4_bits; |
| 604 | /* Sanity checks */ |
| 605 | ASSERT(c_max > 0); |
| 606 | ASSERT(u4_range >= 256); |
| 607 | u4_sym = 0; |
| 608 | BITS_NXT(u4_bits, ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 609 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, (UWORD32)c_max); |
| 610 | u4_bits <<= (32 - c_max); |
| 611 | do |
| 612 | { |
| 613 | u4_ofst <<= 1; |
| 614 | u4_ofst |= (u4_bits >> 31); |
| 615 | u4_bits <<= 1; |
| 616 | |
| 617 | bin = 0; |
| 618 | if(u4_ofst >= u4_range) |
| 619 | { |
| 620 | bin = 1; |
| 621 | u4_ofst -= u4_range; |
| 622 | } |
| 623 | u4_sym++; |
| 624 | }while(((WORD32)u4_sym < c_max) && bin); |
| 625 | BITS_FLUSH(ps_bitstrm->pu4_buf, ps_bitstrm->u4_bit_ofst, |
| 626 | ps_bitstrm->u4_cur_word, ps_bitstrm->u4_nxt_word, u4_sym); |
| 627 | |
| 628 | u4_sym = u4_sym - 1 + bin; |
| 629 | /* Update the cabac context */ |
| 630 | ps_cabac->u4_ofst = u4_ofst; |
| 631 | |
| 632 | return (u4_sym); |
| 633 | } |
| 634 | |
| 635 | /** |
| 636 | ****************************************************************************** |
| 637 | * |
| 638 | * @brief Decodes a syntax element as kth order Exp-Golomb code (EGK) |
| 639 | * |
| 640 | * @par Description |
| 641 | * Decodes a syntax element binarized as kth order Exp-Golomb code (EGK) |
| 642 | * Elements are coded as bypass bins |
| 643 | * |
| 644 | * @param[in,out] ps_cabac |
| 645 | * pointer to cabac context (handle) |
| 646 | * |
| 647 | * @param[in] u4_sym |
| 648 | * syntax element to be coded as EGK |
| 649 | * |
| 650 | * @param[in] k |
| 651 | * order of EGk |
| 652 | * |
| 653 | * @return success or failure error code |
| 654 | * |
| 655 | ****************************************************************************** |
| 656 | */ |
| 657 | UWORD32 ihevcd_cabac_decode_bypass_bins_egk(cab_ctxt_t *ps_cabac, |
| 658 | bitstrm_t *ps_bitstrm, |
| 659 | WORD32 k) |
| 660 | { |
| 661 | |
| 662 | UWORD32 u4_sym; |
| 663 | WORD32 numones; |
| 664 | WORD32 bin; |
| 665 | |
| 666 | /* Sanity checks */ |
| 667 | ASSERT((k >= 0)); |
| 668 | |
| 669 | numones = k; |
| 670 | bin = 1; |
| 671 | u4_sym = 0; |
Harish Mahendrakar | 9a4f03d | 2017-01-13 16:41:33 +0530 | [diff] [blame] | 672 | while(bin && (numones <= 16)) |
Harish Mahendrakar | 0d8951c | 2014-05-16 10:31:13 -0700 | [diff] [blame] | 673 | { |
| 674 | IHEVCD_CABAC_DECODE_BYPASS_BIN(bin, ps_cabac, ps_bitstrm); |
| 675 | u4_sym += bin << numones++; |
| 676 | } |
| 677 | |
| 678 | numones -= 1; |
Harish Mahendrakar | 0d8951c | 2014-05-16 10:31:13 -0700 | [diff] [blame] | 679 | |
| 680 | if(numones) |
| 681 | { |
| 682 | UWORD32 u4_suffix; |
| 683 | |
| 684 | IHEVCD_CABAC_DECODE_BYPASS_BINS(u4_suffix, ps_cabac, ps_bitstrm, numones); |
| 685 | u4_sym += u4_suffix; |
| 686 | } |
| 687 | return (u4_sym); |
| 688 | } |
| 689 | |
| 690 | /** |
| 691 | ****************************************************************************** |
| 692 | * |
| 693 | * @brief Decodes a syntax element as truncated rice code (TR) |
| 694 | * |
| 695 | * @par Description |
| 696 | * Decodes a syntax element as truncated rice code (TR) |
| 697 | * Elements are coded as bypass bins |
| 698 | * This function ise used for coeff_abs_level_remaining coding when |
| 699 | * level is less than c_rice_max |
| 700 | * |
| 701 | * @param[in,out] ps_cabac |
| 702 | * pointer to cabac context (handle) |
| 703 | * |
| 704 | * @param[in] u4_sym |
| 705 | * syntax element to be coded as truncated rice code |
| 706 | * |
| 707 | * @param[in] c_rice_param |
| 708 | * shift factor for truncated unary prefix coding of (u4_sym >> c_rice_param) |
| 709 | * |
| 710 | * @param[in] c_rice_max |
| 711 | * max symbol val below which a suffix is coded as (u4_sym%(1<<c_rice_param)) |
| 712 | * This is currently (4 << c_rice_param) for coeff_abs_level_remaining |
| 713 | * |
| 714 | * @return success or failure error code |
| 715 | * |
| 716 | ****************************************************************************** |
| 717 | */ |
| 718 | UWORD32 ihevcd_cabac_decode_bypass_bins_trunc_rice(cab_ctxt_t *ps_cabac, |
| 719 | bitstrm_t *ps_bitstrm, |
| 720 | WORD32 c_rice_param, |
| 721 | WORD32 c_rice_max) |
| 722 | { |
| 723 | UWORD32 u4_sym; |
| 724 | WORD32 bin; |
| 725 | WORD32 c_max; |
| 726 | UWORD32 u4_suffix; |
| 727 | /* Sanity checks */ |
| 728 | ASSERT((c_rice_param >= 0)); |
| 729 | |
| 730 | |
| 731 | /* Decode prefix coded as TUnary */ |
| 732 | c_max = c_rice_max >> c_rice_param; |
| 733 | u4_sym = 0; |
| 734 | do |
| 735 | { |
| 736 | IHEVCD_CABAC_DECODE_BYPASS_BIN(bin, ps_cabac, ps_bitstrm); |
| 737 | u4_sym++; |
| 738 | |
| 739 | }while(((WORD32)u4_sym < c_max) && bin); |
| 740 | u4_sym = u4_sym - 1 + bin; |
| 741 | |
| 742 | /* If suffix is present, then decode c_rice_param number of bins */ |
| 743 | if(c_rice_param) |
| 744 | { |
| 745 | IHEVCD_CABAC_DECODE_BYPASS_BINS(u4_suffix, ps_cabac, ps_bitstrm, c_rice_param); |
| 746 | |
| 747 | u4_sym = (u4_sym << c_rice_param) | u4_suffix; |
| 748 | } |
| 749 | return (u4_sym); |
| 750 | } |