/*

 * 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 AVM_AV2_COMMON_COST_H_

#define AVM_AV2_COMMON_COST_H_

#include "avm_dsp/prob.h"

#include "avm/avm_integer.h"

#ifdef __cplusplus

extern "C" {

#endif

extern const uint16_t av2_prob_cost[128];

// The factor to scale from cost in bits to cost in av2_prob_cost units.

#define AV2_PROB_COST_SHIFT 9

// Cost of coding an n bit literal, using 128 (i.e. 50%) probability

// for each bit.

#define av2_cost_literal(n) ((n) * (1 << AV2_PROB_COST_SHIFT))

// Calculate the cost of a symbol with probability p15 / 2^15

static INLINE int av2_cost_symbol(avm_cdf_prob p15) {

  // p15 can be out of range [1, CDF_PROB_TOP - 1]. Clamping it, so that the

  // following cost calculation works correctly. Otherwise, if p15 =

  // CDF_PROB_TOP, shift would be -1, and "p15 << shift" would be wrong.

  p15 = (avm_cdf_prob)clamp(p15, 1, CDF_PROB_TOP - 1);

  assert(0 < p15 && p15 < CDF_PROB_TOP);

  const int shift = CDF_PROB_BITS - 1 - get_msb(p15);

  const int prob = get_prob(p15 << shift, CDF_PROB_TOP);

  assert(prob >= 128);

  return av2_prob_cost[prob - 128] + av2_cost_literal(shift);

}

void av2_cost_tokens_from_cdf(int *costs, const avm_cdf_prob *cdf,

                              const int nsym, const int *inv_map);

#ifdef __cplusplus

}  // extern "C"

#endif

#endif  // AVM_AV2_COMMON_COST_H_