/*
  * AAC encoder utilities
  * Copyright (C) 2015 Rostislav Pehlivanov
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file
  * AAC encoder utilities
  * @author Rostislav Pehlivanov ( atomnuker gmail com )
  */
 
 #ifndef AVCODEC_AACENC_UTILS_H
 #define AVCODEC_AACENC_UTILS_H
 

 #include "libavutil/ffmath.h"

 #include "aac.h"
 #include "aacenctab.h"

 #include "aactab.h"

 
 #define ROUND_STANDARD 0.4054f
 #define ROUND_TO_ZERO 0.1054f
 #define C_QUANT 0.4054f
 
 static inline void abs_pow34_v(float *out, const float *in, const int size)
 {
     int i;
     for (i = 0; i < size; i++) {
         float a = fabsf(in[i]);
         out[i] = sqrtf(a * sqrtf(a));
     }
 }
 

 static inline float pos_pow34(float a)
 {
     return sqrtf(a * sqrtf(a));
 }
 

 /**
  * Quantize one coefficient.
  * @return absolute value of the quantized coefficient
  * @see 3GPP TS26.403 5.6.2 "Scalefactor determination"
  */
 static inline int quant(float coef, const float Q, const float rounding)
 {
     float a = coef * Q;
     return sqrtf(a * sqrtf(a)) + rounding;
 }
 
 static inline void quantize_bands(int *out, const float *in, const float *scaled,

                                   int size, int is_signed, int maxval, const float Q34,

                                   const float rounding)
 {
     int i;
     for (i = 0; i < size; i++) {

         float qc = scaled[i] * Q34;

         int tmp = (int)FFMIN(qc + rounding, (float)maxval);

         if (is_signed && in[i] < 0.0f) {

             tmp = -tmp;

         }

         out[i] = tmp;

     }
 }
 
 static inline float find_max_val(int group_len, int swb_size, const float *scaled)
 {
     float maxval = 0.0f;
     int w2, i;
     for (w2 = 0; w2 < group_len; w2++) {
         for (i = 0; i < swb_size; i++) {
             maxval = FFMAX(maxval, scaled[w2*128+i]);
         }
     }
     return maxval;
 }
 
 static inline int find_min_book(float maxval, int sf)
 {

     float Q34 = ff_aac_pow34sf_tab[POW_SF2_ZERO - sf + SCALE_ONE_POS - SCALE_DIV_512];

     int qmaxval, cb;
     qmaxval = maxval * Q34 + C_QUANT;

     if (qmaxval >= (FF_ARRAY_ELEMS(aac_maxval_cb)))
         cb = 11;
     else
         cb = aac_maxval_cb[qmaxval];

     return cb;
 }
 

 static inline float find_form_factor(int group_len, int swb_size, float thresh,
                                      const float *scaled, float nzslope) {

     const float iswb_size = 1.0f / swb_size;
     const float iswb_sizem1 = 1.0f / (swb_size - 1);
     const float ethresh = thresh;
     float form = 0.0f, weight = 0.0f;
     int w2, i;
     for (w2 = 0; w2 < group_len; w2++) {
         float e = 0.0f, e2 = 0.0f, var = 0.0f, maxval = 0.0f;
         float nzl = 0;
         for (i = 0; i < swb_size; i++) {
             float s = fabsf(scaled[w2*128+i]);
             maxval = FFMAX(maxval, s);
             e += s;
             e2 += s *= s;
             /* We really don't want a hard non-zero-line count, since
              * even below-threshold lines do add up towards band spectral power.
              * So, fall steeply towards zero, but smoothly
              */
             if (s >= ethresh) {
                 nzl += 1.0f;
             } else {

                 if (nzslope == 2.f)
                     nzl += (s / ethresh) * (s / ethresh);
                 else
                     nzl += ff_fast_powf(s / ethresh, nzslope);

             }
         }
         if (e2 > thresh) {
             float frm;
             e *= iswb_size;
 
             /** compute variance */
             for (i = 0; i < swb_size; i++) {
                 float d = fabsf(scaled[w2*128+i]) - e;
                 var += d*d;
             }
             var = sqrtf(var * iswb_sizem1);
 
             e2 *= iswb_size;
             frm = e / FFMIN(e+4*var,maxval);
             form += e2 * sqrtf(frm) / FFMAX(0.5f,nzl);
             weight += e2;
         }
     }
     if (weight > 0) {
         return form / weight;
     } else {
         return 1.0f;
     }
 }
 

 /** Return the minimum scalefactor where the quantized coef does not clip. */
 static inline uint8_t coef2minsf(float coef)
 {
     return av_clip_uint8(log2f(coef)*4 - 69 + SCALE_ONE_POS - SCALE_DIV_512);
 }
 
 /** Return the maximum scalefactor where the quantized coef is not zero. */
 static inline uint8_t coef2maxsf(float coef)
 {
     return av_clip_uint8(log2f(coef)*4 +  6 + SCALE_ONE_POS - SCALE_DIV_512);
 }
 
 /*
  * Returns the closest possible index to an array of float values, given a value.
  */
 static inline int quant_array_idx(const float val, const float *arr, const int num)
 {
     int i, index = 0;
     float quant_min_err = INFINITY;
     for (i = 0; i < num; i++) {
         float error = (val - arr[i])*(val - arr[i]);
         if (error < quant_min_err) {
             quant_min_err = error;
             index = i;
         }
     }
     return index;
 }
 

 /**
  * approximates exp10f(-3.0f*(0.5f + 0.5f * cosf(FFMIN(b,15.5f) / 15.5f)))
  */
 static av_always_inline float bval2bmax(float b)
 {
     return 0.001f + 0.0035f * (b*b*b) / (15.5f*15.5f*15.5f);
 }
 

 /*

  * Compute a nextband map to be used with SF delta constraint utilities.
  * The nextband array should contain 128 elements, and positions that don't
  * map to valid, nonzero bands of the form w*16+g (with w being the initial
  * window of the window group, only) are left indetermined.
  */
 static inline void ff_init_nextband_map(const SingleChannelElement *sce, uint8_t *nextband)
 {
     unsigned char prevband = 0;
     int w, g;
     /** Just a safe default */
     for (g = 0; g < 128; g++)
         nextband[g] = g;
 
     /** Now really navigate the nonzero band chain */
     for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
         for (g = 0; g < sce->ics.num_swb; g++) {
             if (!sce->zeroes[w*16+g] && sce->band_type[w*16+g] < RESERVED_BT)
                 prevband = nextband[prevband] = w*16+g;
         }
     }
     nextband[prevband] = prevband; /* terminate */
 }
 
 /*
  * Updates nextband to reflect a removed band (equivalent to
  * calling ff_init_nextband_map after marking a band as zero)
  */
 static inline void ff_nextband_remove(uint8_t *nextband, int prevband, int band)
 {
     nextband[prevband] = nextband[band];
 }
 
 /*
  * Checks whether the specified band could be removed without inducing
  * scalefactor delta that violates SF delta encoding constraints.
  * prev_sf has to be the scalefactor of the previous nonzero, nonspecial
  * band, in encoding order, or negative if there was no such band.
  */
 static inline int ff_sfdelta_can_remove_band(const SingleChannelElement *sce,
     const uint8_t *nextband, int prev_sf, int band)
 {
     return prev_sf >= 0
         && sce->sf_idx[nextband[band]] >= (prev_sf - SCALE_MAX_DIFF)
         && sce->sf_idx[nextband[band]] <= (prev_sf + SCALE_MAX_DIFF);
 }
 
 /*
  * Checks whether the specified band's scalefactor could be replaced
  * with another one without violating SF delta encoding constraints.
  * prev_sf has to be the scalefactor of the previous nonzero, nonsepcial
  * band, in encoding order, or negative if there was no such band.
  */
 static inline int ff_sfdelta_can_replace(const SingleChannelElement *sce,
     const uint8_t *nextband, int prev_sf, int new_sf, int band)
 {
     return new_sf >= (prev_sf - SCALE_MAX_DIFF)
         && new_sf <= (prev_sf + SCALE_MAX_DIFF)
         && sce->sf_idx[nextband[band]] >= (new_sf - SCALE_MAX_DIFF)
         && sce->sf_idx[nextband[band]] <= (new_sf + SCALE_MAX_DIFF);
 }
 

 /**
  * linear congruential pseudorandom number generator
  *
  * @param   previous_val    pointer to the current state of the generator
  *
  * @return  Returns a 32-bit pseudorandom integer
  */
 static av_always_inline int lcg_random(unsigned previous_val)
 {
     union { unsigned u; int s; } v = { previous_val * 1664525u + 1013904223 };
     return v.s;
 }
 

 #define ERROR_IF(cond, ...) \
     if (cond) { \
         av_log(avctx, AV_LOG_ERROR, __VA_ARGS__); \
         return AVERROR(EINVAL); \
     }
 
 #define WARN_IF(cond, ...) \
     if (cond) { \
         av_log(avctx, AV_LOG_WARNING, __VA_ARGS__); \
     }
 
 #endif /* AVCODEC_AACENC_UTILS_H */