/*

 * Copyright (c) 2016, Alliance for Open Media. All rights reserved.

 *

 * This source code is subject to the terms of the BSD 2 Clause License and

 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

 * was not distributed with this source code in the LICENSE file, you can

 * obtain it at www.aomedia.org/license/software. 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 www.aomedia.org/license/patent.

 */

#include <assert.h>

#include <limits.h>

#include <stdlib.h>

#include "config/aom_config.h"

#include "aom_dsp/bitwriter_buffer.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;

}

static void 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--) 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);

}

static void wb_write_primitive_quniform(struct aom_write_bit_buffer *wb,

                                        uint16_t n, uint16_t v) {

  if (n <= 1) return;

  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);

  }

}

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) {

      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;

      }

    }

  }

}

static void wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,

                                            uint16_t n, uint16_t k,

                                            uint16_t ref, uint16_t v) {

  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) {

  ref += n - 1;

  v += n - 1;

  const uint16_t scaled_n = (n << 1) - 1;

  wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref, v);

}