aom_dsp/bitwriter_buffer.c - 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/.
  */

 #include "aom_dsp/bitwriter_buffer.h"

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

 #include "config/aom_config.h"

 #include "aom_dsp/recenter.h"
 #include "aom_ports/bitops.h"

 int aom_wb_is_byte_aligned(const struct aom_write_bit_buffer *wb) {
   return (wb->bit_offset % CHAR_BIT == 0);
 }

 uint32_t aom_wb_bytes_written(const struct aom_write_bit_buffer *wb) {
   return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
 }

 void aom_wb_write_bit(struct aom_write_bit_buffer *wb, int bit) {
   const int off = (int)wb->bit_offset;
   const int p = off / CHAR_BIT;
   const int q = CHAR_BIT - 1 - off % CHAR_BIT;
   if (q == CHAR_BIT - 1) {
     // Zero next char and write bit
     wb->bit_buffer[p] = bit << q;
   } else {
     wb->bit_buffer[p] &= ~(1 << q);
     wb->bit_buffer[p] |= bit << q;
   }
   wb->bit_offset = off + 1;
 }

 void aom_wb_overwrite_bit(struct aom_write_bit_buffer *wb, int bit) {
   // Do not zero bytes but overwrite exisiting values
   const int off = (int)wb->bit_offset;
   const int p = off / CHAR_BIT;
   const int q = CHAR_BIT - 1 - off % CHAR_BIT;
   wb->bit_buffer[p] &= ~(1 << q);
   wb->bit_buffer[p] |= bit << q;
   wb->bit_offset = off + 1;
 }

 void aom_wb_write_literal(struct aom_write_bit_buffer *wb, int data, int bits) {
   assert(bits <= 31);
   int bit;
   for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
 }

 void aom_wb_write_unsigned_literal(struct aom_write_bit_buffer *wb,
                                    uint32_t data, int bits) {
   assert(bits <= 32);
   int bit;
   for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
 }

 void aom_wb_overwrite_literal(struct aom_write_bit_buffer *wb, int data,
                               int bits) {
   int bit;
   for (bit = bits - 1; bit >= 0; bit--)
     aom_wb_overwrite_bit(wb, (data >> bit) & 1);
 }

 void aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer *wb, int data,
                                      int bits) {
   aom_wb_write_literal(wb, data, bits + 1);
 }

 void aom_wb_write_uvlc(struct aom_write_bit_buffer *wb, uint32_t v) {
   assert(v != UINT32_MAX);
   ++v;
   const int leading_zeroes = get_msb(v);
   aom_wb_write_literal(wb, 0, leading_zeroes);
   aom_wb_write_unsigned_literal(wb, v, leading_zeroes + 1);
 }

 void aom_wb_write_svlc(struct aom_write_bit_buffer *wb, int32_t v) {
   assert(v != INT32_MIN);
   if (v <= 0) {
     const uint32_t abs_val = (uint32_t)(-v);
     aom_wb_write_uvlc(wb, 2 * abs_val);
   } else {
     const uint32_t abs_val = (uint32_t)v;
     aom_wb_write_uvlc(wb, 2 * abs_val - 1);
   }
 }

 void aom_wb_write_primitive_quniform(struct aom_write_bit_buffer *wb,
                                      uint16_t n, uint16_t v) {
   if (n <= 1) return;
   assert(v < n);
   // Split the valid range into two.
   // The encoded value is in the range [0, n), but in order to map a range
   // which may not be a power of 2 onto a binary code, we split into the
   // sub-ranges [0, m) and [m, n), where m is an intermediate point.
   // Values in the range [0, m) then use one fewer bit than values in
   // the range [m, n).
   const int l = get_msb(n) + 1;
   const int m = (1 << l) - n;
   if (v < m) {
     aom_wb_write_literal(wb, v, l - 1);
   } else {
     aom_wb_write_literal(wb, m + ((v - m) >> 1), l - 1);
     aom_wb_write_bit(wb, (v - m) & 1);
   }
 }

 void aom_wb_write_primitive_ref_quniform(struct aom_write_bit_buffer *wb,
                                          uint16_t n, uint16_t r, uint16_t v) {
   // Signal a single bit to indicate if the value is unequal to the reference r
   // If unequal signal a (n - 1)-ary quasi-uniform code where v values
   // higher than r are reduced by 1.
   const int unequal = (v != r);
   aom_wb_write_bit(wb, unequal);
   if (unequal) {
     v -= (v > r);
     aom_wb_write_primitive_quniform(wb, n - 1, v);
   }
 }

 #if CONFIG_LR_FRAMEFILTERS_IN_HEADER
 static int wb_count_primitive_quniform(uint16_t n, uint16_t v) {
   int bits = 0;
   if (n <= 1) return 0;
   assert(v < n);
   const int l = get_msb(n) + 1;
   const int m = (1 << l) - n;
   if (v < m) {
     bits += l - 1;
   } else {
     bits += l;
   }
   return bits;
 }
 #endif  // CONFIG_LR_FRAMEFILTERS_IN_HEADER

 static void wb_write_primitive_subexpfin(struct aom_write_bit_buffer *wb,
                                          uint16_t n, uint16_t k, uint16_t v) {
   int i = 0;
   int mk = 0;
   while (1) {
     int b = (i ? k + i - 1 : k);
     int a = (1 << b);
     if (n <= mk + 3 * a) {
       aom_wb_write_primitive_quniform(wb, n - mk, v - mk);
       break;
     } else {
       int t = (v >= mk + a);
       aom_wb_write_bit(wb, t);
       if (t) {
         i = i + 1;
         mk += a;
       } else {
         aom_wb_write_literal(wb, v - mk, b);
         break;
       }
     }
   }
 }

 #if CONFIG_LR_FRAMEFILTERS_IN_HEADER
 static int wb_count_primitive_subexpfin(uint16_t n, uint16_t k, uint16_t v) {
   int bits = 0;
   int i = 0;
   int mk = 0;
   while (1) {
     int b = (i ? k + i - 1 : k);
     int a = (1 << b);
     if (n <= mk + 3 * a) {
       bits += wb_count_primitive_quniform(n - mk, v - mk);
       break;
     } else {
       int t = (v >= mk + a);
       bits++;
       if (t) {
         i = i + 1;
         mk += a;
       } else {
         bits += b;
         break;
       }
     }
   }
   return bits;
 }
 #endif  // CONFIG_LR_FRAMEFILTERS_IN_HEADER

 void aom_wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
                                          uint16_t n, uint16_t k, uint16_t ref,
                                          uint16_t v) {
   assert(ref < n);
   assert(v < n);
   wb_write_primitive_subexpfin(wb, n, k, recenter_finite_nonneg(n, ref, v));
 }

 void aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
                                                 uint16_t n, uint16_t k,
                                                 int16_t ref, int16_t v) {
   assert(n > 0);
   const uint16_t offset = n - 1;
   const uint16_t scaled_n = (n << 1) - 1;
   aom_wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref + offset,
                                       v + offset);
 }

 #if CONFIG_LR_FRAMEFILTERS_IN_HEADER
 int aom_wb_count_primitive_refsubexpfin(uint16_t n, uint16_t k, int16_t ref,
                                         int16_t v) {
   assert(ref < n);
   assert(v < n);
   return wb_count_primitive_subexpfin(n, k, recenter_finite_nonneg(n, ref, v));
 }
 #endif  // CONFIG_LR_FRAMEFILTERS_IN_HEADER

 #if CONFIG_MULTILAYER_HLS
 // implementation of leb128() signaling in the specification using
 // aom_write_bit_buffer
 void aom_wb_write_uleb(struct aom_write_bit_buffer *wb, uint32_t value) {
   uint32_t enc_val = value;
   const size_t leb_size = aom_uleb_size_in_bytes(enc_val);
   for (size_t i = 0; i < leb_size; ++i) {
     uint8_t encoded_byte = enc_val & 0x7f;
     enc_val >>= 7;
     if (enc_val != 0) encoded_byte |= 0x80;  // Signal that more bytes follow.
     aom_wb_write_literal(wb, encoded_byte, 8);
   }
 }
 #endif  // CONFIG_MULTILAYER_HLS
	/*
	* 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/.
	*/

	#include "aom_dsp/bitwriter_buffer.h"

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

	#include "config/aom_config.h"

	#include "aom_dsp/recenter.h"
	#include "aom_ports/bitops.h"

	int aom_wb_is_byte_aligned(const struct aom_write_bit_buffer *wb) {
	return (wb->bit_offset % CHAR_BIT == 0);
	}

	uint32_t aom_wb_bytes_written(const struct aom_write_bit_buffer *wb) {
	return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
	}

	void aom_wb_write_bit(struct aom_write_bit_buffer *wb, int bit) {
	const int off = (int)wb->bit_offset;
	const int p = off / CHAR_BIT;
	const int q = CHAR_BIT - 1 - off % CHAR_BIT;
	if (q == CHAR_BIT - 1) {
	// Zero next char and write bit
	wb->bit_buffer[p] = bit << q;
	} else {
	wb->bit_buffer[p] &= ~(1 << q);
	wb->bit_buffer[p] \|= bit << q;
	}
	wb->bit_offset = off + 1;
	}

	void aom_wb_overwrite_bit(struct aom_write_bit_buffer *wb, int bit) {
	// Do not zero bytes but overwrite exisiting values
	const int off = (int)wb->bit_offset;
	const int p = off / CHAR_BIT;
	const int q = CHAR_BIT - 1 - off % CHAR_BIT;
	wb->bit_buffer[p] &= ~(1 << q);
	wb->bit_buffer[p] \|= bit << q;
	wb->bit_offset = off + 1;
	}

	void aom_wb_write_literal(struct aom_write_bit_buffer *wb, int data, int bits) {
	assert(bits <= 31);
	int bit;
	for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
	}

	void aom_wb_write_unsigned_literal(struct aom_write_bit_buffer *wb,
	uint32_t data, int bits) {
	assert(bits <= 32);
	int bit;
	for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
	}

	void aom_wb_overwrite_literal(struct aom_write_bit_buffer *wb, int data,
	int bits) {
	int bit;
	for (bit = bits - 1; bit >= 0; bit--)
	aom_wb_overwrite_bit(wb, (data >> bit) & 1);
	}

	void aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer *wb, int data,
	int bits) {
	aom_wb_write_literal(wb, data, bits + 1);
	}

	void aom_wb_write_uvlc(struct aom_write_bit_buffer *wb, uint32_t v) {
	assert(v != UINT32_MAX);
	++v;
	const int leading_zeroes = get_msb(v);
	aom_wb_write_literal(wb, 0, leading_zeroes);
	aom_wb_write_unsigned_literal(wb, v, leading_zeroes + 1);
	}

	void aom_wb_write_svlc(struct aom_write_bit_buffer *wb, int32_t v) {
	assert(v != INT32_MIN);
	if (v <= 0) {
	const uint32_t abs_val = (uint32_t)(-v);
	aom_wb_write_uvlc(wb, 2 * abs_val);
	} else {
	const uint32_t abs_val = (uint32_t)v;
	aom_wb_write_uvlc(wb, 2 * abs_val - 1);
	}
	}

	void aom_wb_write_primitive_quniform(struct aom_write_bit_buffer *wb,
	uint16_t n, uint16_t v) {
	if (n <= 1) return;
	assert(v < n);
	// Split the valid range into two.
	// The encoded value is in the range [0, n), but in order to map a range
	// which may not be a power of 2 onto a binary code, we split into the
	// sub-ranges [0, m) and [m, n), where m is an intermediate point.
	// Values in the range [0, m) then use one fewer bit than values in
	// the range [m, n).
	const int l = get_msb(n) + 1;
	const int m = (1 << l) - n;
	if (v < m) {
	aom_wb_write_literal(wb, v, l - 1);
	} else {
	aom_wb_write_literal(wb, m + ((v - m) >> 1), l - 1);
	aom_wb_write_bit(wb, (v - m) & 1);
	}
	}

	void aom_wb_write_primitive_ref_quniform(struct aom_write_bit_buffer *wb,
	uint16_t n, uint16_t r, uint16_t v) {
	// Signal a single bit to indicate if the value is unequal to the reference r
	// If unequal signal a (n - 1)-ary quasi-uniform code where v values
	// higher than r are reduced by 1.
	const int unequal = (v != r);
	aom_wb_write_bit(wb, unequal);
	if (unequal) {
	v -= (v > r);
	aom_wb_write_primitive_quniform(wb, n - 1, v);
	}
	}

	#if CONFIG_LR_FRAMEFILTERS_IN_HEADER
	static int wb_count_primitive_quniform(uint16_t n, uint16_t v) {
	int bits = 0;
	if (n <= 1) return 0;
	assert(v < n);
	const int l = get_msb(n) + 1;
	const int m = (1 << l) - n;
	if (v < m) {
	bits += l - 1;
	} else {
	bits += l;
	}
	return bits;
	}
	#endif // CONFIG_LR_FRAMEFILTERS_IN_HEADER

	static void wb_write_primitive_subexpfin(struct aom_write_bit_buffer *wb,
	uint16_t n, uint16_t k, uint16_t v) {
	int i = 0;
	int mk = 0;
	while (1) {
	int b = (i ? k + i - 1 : k);
	int a = (1 << b);
	if (n <= mk + 3 * a) {
	aom_wb_write_primitive_quniform(wb, n - mk, v - mk);
	break;
	} else {
	int t = (v >= mk + a);
	aom_wb_write_bit(wb, t);
	if (t) {
	i = i + 1;
	mk += a;
	} else {
	aom_wb_write_literal(wb, v - mk, b);
	break;
	}
	}
	}
	}

	#if CONFIG_LR_FRAMEFILTERS_IN_HEADER
	static int wb_count_primitive_subexpfin(uint16_t n, uint16_t k, uint16_t v) {
	int bits = 0;
	int i = 0;
	int mk = 0;
	while (1) {
	int b = (i ? k + i - 1 : k);
	int a = (1 << b);
	if (n <= mk + 3 * a) {
	bits += wb_count_primitive_quniform(n - mk, v - mk);
	break;
	} else {
	int t = (v >= mk + a);
	bits++;
	if (t) {
	i = i + 1;
	mk += a;
	} else {
	bits += b;
	break;
	}
	}
	}
	return bits;
	}
	#endif // CONFIG_LR_FRAMEFILTERS_IN_HEADER

	void aom_wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
	uint16_t n, uint16_t k, uint16_t ref,
	uint16_t v) {
	assert(ref < n);
	assert(v < n);
	wb_write_primitive_subexpfin(wb, n, k, recenter_finite_nonneg(n, ref, v));
	}

	void aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
	uint16_t n, uint16_t k,
	int16_t ref, int16_t v) {
	assert(n > 0);
	const uint16_t offset = n - 1;
	const uint16_t scaled_n = (n << 1) - 1;
	aom_wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref + offset,
	v + offset);
	}

	#if CONFIG_LR_FRAMEFILTERS_IN_HEADER
	int aom_wb_count_primitive_refsubexpfin(uint16_t n, uint16_t k, int16_t ref,
	int16_t v) {
	assert(ref < n);
	assert(v < n);
	return wb_count_primitive_subexpfin(n, k, recenter_finite_nonneg(n, ref, v));
	}
	#endif // CONFIG_LR_FRAMEFILTERS_IN_HEADER

	#if CONFIG_MULTILAYER_HLS
	// implementation of leb128() signaling in the specification using
	// aom_write_bit_buffer
	void aom_wb_write_uleb(struct aom_write_bit_buffer *wb, uint32_t value) {
	uint32_t enc_val = value;
	const size_t leb_size = aom_uleb_size_in_bytes(enc_val);
	for (size_t i = 0; i < leb_size; ++i) {
	uint8_t encoded_byte = enc_val & 0x7f;
	enc_val >>= 7;
	if (enc_val != 0) encoded_byte \|= 0x80; // Signal that more bytes follow.
	aom_wb_write_literal(wb, encoded_byte, 8);
	}
	}
	#endif // CONFIG_MULTILAYER_HLS