aom_dsp/bitreader.h - avm - Git at Google

 /*
  * Copyright (c) 2021, Alliance for Open Media. All rights reserved
  *
  * This source code is subject to the terms of the BSD 3-Clause Clear License
  * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear
  * License was not distributed with this source code in the LICENSE file, you
  * can obtain it at aomedia.org/license/software-license/bsd-3-c-c/.  If the
  * Alliance for Open Media Patent License 1.0 was not distributed with this
  * source code in the PATENTS file, you can obtain it at
  * aomedia.org/license/patent-license/.
  */

 #ifndef AOM_AOM_DSP_BITREADER_H_
 #define AOM_AOM_DSP_BITREADER_H_

 #include <assert.h>
 #include <limits.h>

 #include "config/aom_config.h"

 #include "aom/aomdx.h"
 #include "aom/aom_integer.h"
 #include "aom_dsp/entdec.h"
 #include "aom_dsp/prob.h"
 #include "aom_dsp/recenter.h"
 #include "av1/common/odintrin.h"

 #if CONFIG_BITSTREAM_DEBUG
 #include "aom_util/debug_util.h"
 #endif  // CONFIG_BITSTREAM_DEBUG

 #if CONFIG_ACCOUNTING
 #include "av1/decoder/accounting.h"
 #define ACCT_STR_NAME acct_str
 #define ACCT_STR_PARAM , const char *ACCT_STR_NAME
 #define ACCT_STR_ARG(s) , s
 #else
 #define ACCT_STR_PARAM
 #define ACCT_STR_ARG(s)
 #endif

 #define aom_read(r, prob, ACCT_STR_NAME) \
   aom_read_(r, prob ACCT_STR_ARG(ACCT_STR_NAME))
 #define aom_read_bit(r, ACCT_STR_NAME) \
   aom_read_bit_(r ACCT_STR_ARG(ACCT_STR_NAME))
 #define aom_read_tree(r, tree, probs, ACCT_STR_NAME) \
   aom_read_tree_(r, tree, probs ACCT_STR_ARG(ACCT_STR_NAME))
 #define aom_read_literal(r, bits, ACCT_STR_NAME) \
   aom_read_literal_(r, bits ACCT_STR_ARG(ACCT_STR_NAME))
 #define aom_read_cdf(r, cdf, nsymbs, ACCT_STR_NAME) \
   aom_read_cdf_(r, cdf, nsymbs ACCT_STR_ARG(ACCT_STR_NAME))
 #define aom_read_symbol(r, cdf, nsymbs, ACCT_STR_NAME) \
   aom_read_symbol_(r, cdf, nsymbs ACCT_STR_ARG(ACCT_STR_NAME))
 #if CONFIG_WIENER_NONSEP
 #define aom_read_4part(r, cdf, nsymb_bits, ACCT_STR_NAME) \
   aom_read_4part_(r, cdf, nsymb_bits ACCT_STR_ARG(ACCT_STR_NAME))
 #define aom_read_4part_wref(r, ref_symb, cdf, nsymb_bits, ACCT_STR_NAME) \
   aom_read_4part_wref_(r, ref_symb, cdf, nsymb_bits ACCT_STR_ARG(ACCT_STR_NAME))
 #endif  // CONFIG_WIENER_NONSEP

 #ifdef __cplusplus
 extern "C" {
 #endif

 struct aom_reader {
   const uint8_t *buffer;
   const uint8_t *buffer_end;
   od_ec_dec ec;
 #if CONFIG_ACCOUNTING
   Accounting *accounting;
 #endif
   uint8_t allow_update_cdf;
 };

 typedef struct aom_reader aom_reader;

 int aom_reader_init(aom_reader *r, const uint8_t *buffer, size_t size);

 const uint8_t *aom_reader_find_begin(aom_reader *r);

 const uint8_t *aom_reader_find_end(aom_reader *r);

 // Returns true if the bit reader has tried to decode more data from the buffer
 // than was actually provided.
 int aom_reader_has_overflowed(const aom_reader *r);

 // Returns the position in the bit reader in bits.
 uint32_t aom_reader_tell(const aom_reader *r);

 // Returns the position in the bit reader in 1/8th bits.
 uint32_t aom_reader_tell_frac(const aom_reader *r);

 #if CONFIG_ACCOUNTING
 static INLINE void aom_process_accounting(const aom_reader *r ACCT_STR_PARAM) {
   if (r->accounting != NULL) {
     uint32_t tell_frac;
     tell_frac = aom_reader_tell_frac(r);
     aom_accounting_record(r->accounting, ACCT_STR_NAME,
                           tell_frac - r->accounting->last_tell_frac);
     r->accounting->last_tell_frac = tell_frac;
   }
 }

 #if CONFIG_THROUGHPUT_ANALYSIS
 static INLINE void aom_update_symb_counts(const aom_reader *r, int is_binary,
                                           int is_context_coded) {
 #else
 static INLINE void aom_update_symb_counts(const aom_reader *r, int is_binary) {
 #endif  // CONFIG_THROUGHPUT_ANALYSIS
   if (r->accounting != NULL) {
     r->accounting->syms.num_multi_syms += !is_binary;
     r->accounting->syms.num_binary_syms += !!is_binary;
 #if CONFIG_THROUGHPUT_ANALYSIS
     if (is_context_coded) {
       r->accounting->syms.num_ctx_coded += 1;
     } else {
       r->accounting->syms.num_bypass_coded += 1;
     }
 #endif  // CONFIG_THROUGHPUT_ANALYSIS
   }
 }
 #endif

 static INLINE int aom_read_(aom_reader *r, int prob ACCT_STR_PARAM) {
   int p = (0x7FFFFF - (prob << 15) + prob) >> 8;
   int bit = od_ec_decode_bool_q15(&r->ec, p);

 #if CONFIG_BITSTREAM_DEBUG
   {
     int i;
     int ref_bit, ref_nsymbs;
     aom_cdf_prob ref_cdf[16];
     const int queue_r = bitstream_queue_get_read();
     const int frame_idx = aom_bitstream_queue_get_frame_read();
     bitstream_queue_pop(&ref_bit, ref_cdf, &ref_nsymbs);
     if (ref_nsymbs != 2) {
       fprintf(stderr,
               "\n *** [bit] nsymbs error, frame_idx_r %d nsymbs %d ref_nsymbs "
               "%d queue_r %d\n",
               frame_idx, 2, ref_nsymbs, queue_r);
       assert(0);
     }
     if ((ref_nsymbs != 2) || (ref_cdf[0] != (aom_cdf_prob)p) ||
         (ref_cdf[1] != 32767)) {
       fprintf(stderr,
               "\n *** [bit] cdf error, frame_idx_r %d cdf {%d, %d} ref_cdf {%d",
               frame_idx, p, 32767, ref_cdf[0]);
       for (i = 1; i < ref_nsymbs; ++i) fprintf(stderr, ", %d", ref_cdf[i]);
       fprintf(stderr, "} queue_r %d\n", queue_r);
       assert(0);
     }
     if (bit != ref_bit) {
       fprintf(stderr,
               "\n *** [bit] symb error, frame_idx_r %d symb %d ref_symb %d "
               "queue_r %d\n",
               frame_idx, bit, ref_bit, queue_r);
       assert(0);
     }
   }
 #endif

 #if CONFIG_ACCOUNTING
   if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
 #if CONFIG_THROUGHPUT_ANALYSIS
   aom_update_symb_counts(r, 1, 0);
 #else
   aom_update_symb_counts(r, 1);
 #endif  // CONFIG_THROUGHPUT_ANALYSIS
 #endif
   return bit;
 }

 static INLINE int aom_read_bit_(aom_reader *r ACCT_STR_PARAM) {
   int ret;
   ret = aom_read(r, 128, NULL);  // aom_prob_half
 #if CONFIG_ACCOUNTING
   if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
 #endif
   return ret;
 }

 static INLINE int aom_read_literal_(aom_reader *r, int bits ACCT_STR_PARAM) {
   int literal = 0, bit;

   for (bit = bits - 1; bit >= 0; bit--) literal |= aom_read_bit(r, NULL) << bit;
 #if CONFIG_ACCOUNTING
   if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
 #endif
   return literal;
 }

 static INLINE int aom_read_cdf_(aom_reader *r, const aom_cdf_prob *cdf,
                                 int nsymbs ACCT_STR_PARAM) {
   int symb;
   assert(cdf != NULL);
   symb = od_ec_decode_cdf_q15(&r->ec, cdf, nsymbs);

 #if CONFIG_BITSTREAM_DEBUG
   {
     int i;
     int cdf_error = 0;
     int ref_symb, ref_nsymbs;
     aom_cdf_prob ref_cdf[16];
     const int queue_r = bitstream_queue_get_read();
     const int frame_idx = aom_bitstream_queue_get_frame_read();
     bitstream_queue_pop(&ref_symb, ref_cdf, &ref_nsymbs);
     if (nsymbs != ref_nsymbs) {
       fprintf(stderr,
               "\n *** nsymbs error, frame_idx_r %d nsymbs %d ref_nsymbs %d "
               "queue_r %d\n",
               frame_idx, nsymbs, ref_nsymbs, queue_r);
       cdf_error = 0;
       assert(0);
     } else {
       for (i = 0; i < nsymbs; ++i)
         if (cdf[i] != ref_cdf[i]) cdf_error = 1;
     }
     if (cdf_error) {
       fprintf(stderr, "\n *** cdf error, frame_idx_r %d cdf {%d", frame_idx,
               cdf[0]);
       for (i = 1; i < nsymbs; ++i) fprintf(stderr, ", %d", cdf[i]);
       fprintf(stderr, "} ref_cdf {%d", ref_cdf[0]);
       for (i = 1; i < ref_nsymbs; ++i) fprintf(stderr, ", %d", ref_cdf[i]);
       fprintf(stderr, "} queue_r %d\n", queue_r);
       assert(0);
     }
     if (symb != ref_symb) {
       fprintf(
           stderr,
           "\n *** symb error, frame_idx_r %d symb %d ref_symb %d queue_r %d\n",
           frame_idx, symb, ref_symb, queue_r);
       assert(0);
     }
   }
 #endif

 #if CONFIG_ACCOUNTING
   if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
 #if CONFIG_THROUGHPUT_ANALYSIS
   aom_update_symb_counts(r, (nsymbs == 2), 1);
 #else
   aom_update_symb_counts(r, (nsymbs == 2));
 #endif  // CONFIG_THROUGHPUT_ANALYSIS
 #endif
   return symb;
 }

 static INLINE int aom_read_symbol_(aom_reader *r, aom_cdf_prob *cdf,
                                    int nsymbs ACCT_STR_PARAM) {
   int ret;
   ret = aom_read_cdf(r, cdf, nsymbs, ACCT_STR_NAME);
   if (r->allow_update_cdf) update_cdf(cdf, ret, nsymbs);
   return ret;
 }

 #if CONFIG_WIENER_NONSEP
 // Implements a code where a symbol with an alphabet size a power of 2 with
 // nsymb_bits bits (with nsymb_bits >= 3), is coded by decomposing the symbol
 // into 4 parts convering 1/8, 1/8, 1/4, 1/2 of the total number of symbols.
 // The part is arithmetically coded using the provided cdf of size 4. The
 // offset within each part is coded using fixed length binary codes with
 // (nsymb_bits - 3), (nsymb_bits - 3), (nsymb_bits - 2) or (nsymb_bits - 1)
 // bits, depending on the part.
 static INLINE int aom_read_4part_(aom_reader *r, aom_cdf_prob *cdf,
                                   int nsymb_bits ACCT_STR_PARAM) {
   assert(nsymb_bits >= 3);
   int part_bits[4] = { (nsymb_bits - 3), (nsymb_bits - 3), (nsymb_bits - 2),
                        (nsymb_bits - 1) };
   int part_offs[4] = { 0, 1 << (nsymb_bits - 3), 1 << (nsymb_bits - 2),
                        1 << (nsymb_bits - 1) };
   const int part = aom_read_symbol(r, cdf, 4, ACCT_STR_NAME);
   return aom_read_literal(r, part_bits[part], ACCT_STR_NAME) + part_offs[part];
 }

 // Implements a nsymb_bits bit 4-part code that codes a symbol symb given a
 // reference ref_symb after recentering symb around ref_symb.
 static INLINE int aom_read_4part_wref_(aom_reader *r, int ref_symb,
                                        aom_cdf_prob *cdf,
                                        int nsymb_bits ACCT_STR_PARAM) {
   const int symb = aom_read_4part(r, cdf, nsymb_bits, ACCT_STR_PARAM);
   return inv_recenter_finite_nonneg(1 << nsymb_bits, ref_symb, symb);
 }
 #endif  // CONFIG_WIENER_NONSEP
         //
 #ifdef __cplusplus
 }  // extern "C"
 #endif

 #endif  // AOM_AOM_DSP_BITREADER_H_
	/*
	* Copyright (c) 2021, Alliance for Open Media. All rights reserved
	*
	* This source code is subject to the terms of the BSD 3-Clause Clear License
	* and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear
	* License was not distributed with this source code in the LICENSE file, you
	* can obtain it at aomedia.org/license/software-license/bsd-3-c-c/. If the
	* Alliance for Open Media Patent License 1.0 was not distributed with this
	* source code in the PATENTS file, you can obtain it at
	* aomedia.org/license/patent-license/.
	*/

	#ifndef AOM_AOM_DSP_BITREADER_H_
	#define AOM_AOM_DSP_BITREADER_H_

	#include <assert.h>
	#include <limits.h>

	#include "config/aom_config.h"

	#include "aom/aomdx.h"
	#include "aom/aom_integer.h"
	#include "aom_dsp/entdec.h"
	#include "aom_dsp/prob.h"
	#include "aom_dsp/recenter.h"
	#include "av1/common/odintrin.h"

	#if CONFIG_BITSTREAM_DEBUG
	#include "aom_util/debug_util.h"
	#endif // CONFIG_BITSTREAM_DEBUG

	#if CONFIG_ACCOUNTING
	#include "av1/decoder/accounting.h"
	#define ACCT_STR_NAME acct_str
	#define ACCT_STR_PARAM , const char *ACCT_STR_NAME
	#define ACCT_STR_ARG(s) , s
	#else
	#define ACCT_STR_PARAM
	#define ACCT_STR_ARG(s)
	#endif

	#define aom_read(r, prob, ACCT_STR_NAME) \
	aom_read_(r, prob ACCT_STR_ARG(ACCT_STR_NAME))
	#define aom_read_bit(r, ACCT_STR_NAME) \
	aom_read_bit_(r ACCT_STR_ARG(ACCT_STR_NAME))
	#define aom_read_tree(r, tree, probs, ACCT_STR_NAME) \
	aom_read_tree_(r, tree, probs ACCT_STR_ARG(ACCT_STR_NAME))
	#define aom_read_literal(r, bits, ACCT_STR_NAME) \
	aom_read_literal_(r, bits ACCT_STR_ARG(ACCT_STR_NAME))
	#define aom_read_cdf(r, cdf, nsymbs, ACCT_STR_NAME) \
	aom_read_cdf_(r, cdf, nsymbs ACCT_STR_ARG(ACCT_STR_NAME))
	#define aom_read_symbol(r, cdf, nsymbs, ACCT_STR_NAME) \
	aom_read_symbol_(r, cdf, nsymbs ACCT_STR_ARG(ACCT_STR_NAME))
	#if CONFIG_WIENER_NONSEP
	#define aom_read_4part(r, cdf, nsymb_bits, ACCT_STR_NAME) \
	aom_read_4part_(r, cdf, nsymb_bits ACCT_STR_ARG(ACCT_STR_NAME))
	#define aom_read_4part_wref(r, ref_symb, cdf, nsymb_bits, ACCT_STR_NAME) \
	aom_read_4part_wref_(r, ref_symb, cdf, nsymb_bits ACCT_STR_ARG(ACCT_STR_NAME))
	#endif // CONFIG_WIENER_NONSEP

	#ifdef __cplusplus
	extern "C" {
	#endif

	struct aom_reader {
	const uint8_t *buffer;
	const uint8_t *buffer_end;
	od_ec_dec ec;
	#if CONFIG_ACCOUNTING
	Accounting *accounting;
	#endif
	uint8_t allow_update_cdf;
	};

	typedef struct aom_reader aom_reader;

	int aom_reader_init(aom_reader r, const uint8_t buffer, size_t size);

	const uint8_t aom_reader_find_begin(aom_reader r);

	const uint8_t aom_reader_find_end(aom_reader r);

	// Returns true if the bit reader has tried to decode more data from the buffer
	// than was actually provided.
	int aom_reader_has_overflowed(const aom_reader *r);

	// Returns the position in the bit reader in bits.
	uint32_t aom_reader_tell(const aom_reader *r);

	// Returns the position in the bit reader in 1/8th bits.
	uint32_t aom_reader_tell_frac(const aom_reader *r);

	#if CONFIG_ACCOUNTING
	static INLINE void aom_process_accounting(const aom_reader *r ACCT_STR_PARAM) {
	if (r->accounting != NULL) {
	uint32_t tell_frac;
	tell_frac = aom_reader_tell_frac(r);
	aom_accounting_record(r->accounting, ACCT_STR_NAME,
	tell_frac - r->accounting->last_tell_frac);
	r->accounting->last_tell_frac = tell_frac;
	}
	}

	#if CONFIG_THROUGHPUT_ANALYSIS
	static INLINE void aom_update_symb_counts(const aom_reader *r, int is_binary,
	int is_context_coded) {
	#else
	static INLINE void aom_update_symb_counts(const aom_reader *r, int is_binary) {
	#endif // CONFIG_THROUGHPUT_ANALYSIS
	if (r->accounting != NULL) {
	r->accounting->syms.num_multi_syms += !is_binary;
	r->accounting->syms.num_binary_syms += !!is_binary;
	#if CONFIG_THROUGHPUT_ANALYSIS
	if (is_context_coded) {
	r->accounting->syms.num_ctx_coded += 1;
	} else {
	r->accounting->syms.num_bypass_coded += 1;
	}
	#endif // CONFIG_THROUGHPUT_ANALYSIS
	}
	}
	#endif

	static INLINE int aom_read_(aom_reader *r, int prob ACCT_STR_PARAM) {
	int p = (0x7FFFFF - (prob << 15) + prob) >> 8;
	int bit = od_ec_decode_bool_q15(&r->ec, p);

	#if CONFIG_BITSTREAM_DEBUG
	{
	int i;
	int ref_bit, ref_nsymbs;
	aom_cdf_prob ref_cdf[16];
	const int queue_r = bitstream_queue_get_read();
	const int frame_idx = aom_bitstream_queue_get_frame_read();
	bitstream_queue_pop(&ref_bit, ref_cdf, &ref_nsymbs);
	if (ref_nsymbs != 2) {
	fprintf(stderr,
	"\n *** [bit] nsymbs error, frame_idx_r %d nsymbs %d ref_nsymbs "
	"%d queue_r %d\n",
	frame_idx, 2, ref_nsymbs, queue_r);
	assert(0);
	}
	if ((ref_nsymbs != 2) \|\| (ref_cdf[0] != (aom_cdf_prob)p) \|\|
	(ref_cdf[1] != 32767)) {
	fprintf(stderr,
	"\n *** [bit] cdf error, frame_idx_r %d cdf {%d, %d} ref_cdf {%d",
	frame_idx, p, 32767, ref_cdf[0]);
	for (i = 1; i < ref_nsymbs; ++i) fprintf(stderr, ", %d", ref_cdf[i]);
	fprintf(stderr, "} queue_r %d\n", queue_r);
	assert(0);
	}
	if (bit != ref_bit) {
	fprintf(stderr,
	"\n *** [bit] symb error, frame_idx_r %d symb %d ref_symb %d "
	"queue_r %d\n",
	frame_idx, bit, ref_bit, queue_r);
	assert(0);
	}
	}
	#endif

	#if CONFIG_ACCOUNTING
	if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
	#if CONFIG_THROUGHPUT_ANALYSIS
	aom_update_symb_counts(r, 1, 0);
	#else
	aom_update_symb_counts(r, 1);
	#endif // CONFIG_THROUGHPUT_ANALYSIS
	#endif
	return bit;
	}

	static INLINE int aom_read_bit_(aom_reader *r ACCT_STR_PARAM) {
	int ret;
	ret = aom_read(r, 128, NULL); // aom_prob_half
	#if CONFIG_ACCOUNTING
	if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
	#endif
	return ret;
	}

	static INLINE int aom_read_literal_(aom_reader *r, int bits ACCT_STR_PARAM) {
	int literal = 0, bit;

	for (bit = bits - 1; bit >= 0; bit--) literal \|= aom_read_bit(r, NULL) << bit;
	#if CONFIG_ACCOUNTING
	if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
	#endif
	return literal;
	}

	static INLINE int aom_read_cdf_(aom_reader r, const aom_cdf_prob cdf,
	int nsymbs ACCT_STR_PARAM) {
	int symb;
	assert(cdf != NULL);
	symb = od_ec_decode_cdf_q15(&r->ec, cdf, nsymbs);

	#if CONFIG_BITSTREAM_DEBUG
	{
	int i;
	int cdf_error = 0;
	int ref_symb, ref_nsymbs;
	aom_cdf_prob ref_cdf[16];
	const int queue_r = bitstream_queue_get_read();
	const int frame_idx = aom_bitstream_queue_get_frame_read();
	bitstream_queue_pop(&ref_symb, ref_cdf, &ref_nsymbs);
	if (nsymbs != ref_nsymbs) {
	fprintf(stderr,
	"\n *** nsymbs error, frame_idx_r %d nsymbs %d ref_nsymbs %d "
	"queue_r %d\n",
	frame_idx, nsymbs, ref_nsymbs, queue_r);
	cdf_error = 0;
	assert(0);
	} else {
	for (i = 0; i < nsymbs; ++i)
	if (cdf[i] != ref_cdf[i]) cdf_error = 1;
	}
	if (cdf_error) {
	fprintf(stderr, "\n *** cdf error, frame_idx_r %d cdf {%d", frame_idx,
	cdf[0]);
	for (i = 1; i < nsymbs; ++i) fprintf(stderr, ", %d", cdf[i]);
	fprintf(stderr, "} ref_cdf {%d", ref_cdf[0]);
	for (i = 1; i < ref_nsymbs; ++i) fprintf(stderr, ", %d", ref_cdf[i]);
	fprintf(stderr, "} queue_r %d\n", queue_r);
	assert(0);
	}
	if (symb != ref_symb) {
	fprintf(
	stderr,
	"\n *** symb error, frame_idx_r %d symb %d ref_symb %d queue_r %d\n",
	frame_idx, symb, ref_symb, queue_r);
	assert(0);
	}
	}
	#endif

	#if CONFIG_ACCOUNTING
	if (ACCT_STR_NAME) aom_process_accounting(r, ACCT_STR_NAME);
	#if CONFIG_THROUGHPUT_ANALYSIS
	aom_update_symb_counts(r, (nsymbs == 2), 1);
	#else
	aom_update_symb_counts(r, (nsymbs == 2));
	#endif // CONFIG_THROUGHPUT_ANALYSIS
	#endif
	return symb;
	}

	static INLINE int aom_read_symbol_(aom_reader r, aom_cdf_prob cdf,
	int nsymbs ACCT_STR_PARAM) {
	int ret;
	ret = aom_read_cdf(r, cdf, nsymbs, ACCT_STR_NAME);
	if (r->allow_update_cdf) update_cdf(cdf, ret, nsymbs);
	return ret;
	}

	#if CONFIG_WIENER_NONSEP
	// Implements a code where a symbol with an alphabet size a power of 2 with
	// nsymb_bits bits (with nsymb_bits >= 3), is coded by decomposing the symbol
	// into 4 parts convering 1/8, 1/8, 1/4, 1/2 of the total number of symbols.
	// The part is arithmetically coded using the provided cdf of size 4. The
	// offset within each part is coded using fixed length binary codes with
	// (nsymb_bits - 3), (nsymb_bits - 3), (nsymb_bits - 2) or (nsymb_bits - 1)
	// bits, depending on the part.
	static INLINE int aom_read_4part_(aom_reader r, aom_cdf_prob cdf,
	int nsymb_bits ACCT_STR_PARAM) {
	assert(nsymb_bits >= 3);
	int part_bits[4] = { (nsymb_bits - 3), (nsymb_bits - 3), (nsymb_bits - 2),
	(nsymb_bits - 1) };
	int part_offs[4] = { 0, 1 << (nsymb_bits - 3), 1 << (nsymb_bits - 2),
	1 << (nsymb_bits - 1) };
	const int part = aom_read_symbol(r, cdf, 4, ACCT_STR_NAME);
	return aom_read_literal(r, part_bits[part], ACCT_STR_NAME) + part_offs[part];
	}

	// Implements a nsymb_bits bit 4-part code that codes a symbol symb given a
	// reference ref_symb after recentering symb around ref_symb.
	static INLINE int aom_read_4part_wref_(aom_reader *r, int ref_symb,
	aom_cdf_prob *cdf,
	int nsymb_bits ACCT_STR_PARAM) {
	const int symb = aom_read_4part(r, cdf, nsymb_bits, ACCT_STR_PARAM);
	return inv_recenter_finite_nonneg(1 << nsymb_bits, ref_symb, symb);
	}
	#endif // CONFIG_WIENER_NONSEP
	//
	#ifdef __cplusplus
	} // extern "C"
	#endif

	#endif // AOM_AOM_DSP_BITREADER_H_