apps/codecs/libcook/cook_fixpoint.h

   1 /*
   2  * COOK compatible decoder, fixed point implementation.
   3  * Copyright (c) 2007 Ian Braithwaite
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  *
  21  */
  22
  23 /**
  24  * @file cook_float.h
  25  *
  26  * Cook AKA RealAudio G2 fixed point functions.
  27  *
  28  * Fixed point values are represented as 32 bit signed integers,
  29  * which can be added and subtracted directly in C (without checks for
  30  * overflow/saturation.
  31  * Two multiplication routines are provided:
  32  * 1) Multiplication by powers of two (2^-31 .. 2^31), implemented
  33  *    with C's bit shift operations.
  34  * 2) Multiplication by 16 bit fractions (0 <= x < 1), implemented
  35  *    in C using two 32 bit integer multiplications.
  36  */
  37
  38 /* The following table is taken from libavutil/mathematics.c */
  39 const uint8_t ff_log2_tab[256]={
  40         0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
  41         5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
  42         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  43         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  44         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  45         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  46         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  47         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
  48 };
  49
  50 /* cplscales was moved from cookdata_fixpoint.h since only   *
  51  * cook_fixpoint.h should see/use it.                        */
  52 static const FIXPU* cplscales[5] = {
  53     cplscale2, cplscale3, cplscale4, cplscale5, cplscale6
  54 };
  55
  56 /**
  57  * Fixed point multiply by power of two.
  58  *
  59  * @param x                     fix point value
  60  * @param i                     integer power-of-two, -31..+31
  61  */
  62 static inline FIXP fixp_pow2(FIXP x, int i)
  63 {
  64   if (i < 0)
  65     return (x >> -i) + ((x >> (-i-1)) & 1);
  66   else
  67     return x << i;              /* no check for overflow */
  68 }
  69
  70 /**
  71  * Fixed point multiply by fraction.
  72  *
  73  * @param a                     fix point value
  74  * @param b                     fix point fraction, 0 <= b < 1
  75  */
  76 static inline FIXP fixp_mult_su(FIXP a, FIXPU b)
  77 {
  78     int32_t hb = (a >> 16) * b;
  79     uint32_t lb = (a & 0xffff) * b;
  80
  81     return hb + (lb >> 16) + ((lb & 0x8000) >> 15);
  82 }
  83
  84 /* math functions taken from libavutil/common.h */
  85
  86 static inline int av_log2(unsigned int v)
  87 {
  88     int n = 0;
  89     if (v & 0xffff0000) {
  90         v >>= 16;
  91         n += 16;
  92     }
  93     if (v & 0xff00) {
  94         v >>= 8;
  95         n += 8;
  96     }
  97     n += ff_log2_tab[v];
  98
  99     return n;
 100 }
 101
 102 /**
 103  * Clips a signed integer value into the amin-amax range.
 104  * @param a value to clip
 105  * @param amin minimum value of the clip range
 106  * @param amax maximum value of the clip range
 107  * @return clipped value
 108  */
 109 static inline int av_clip(int a, int amin, int amax)
 110 {
 111     if      (a < amin) return amin;
 112     else if (a > amax) return amax;
 113     else               return a;
 114 }
 115
 116 /**
 117  * The real requantization of the mltcoefs
 118  *
 119  * @param q                     pointer to the COOKContext
 120  * @param index                 index
 121  * @param quant_index           quantisation index for this band
 122  * @param subband_coef_index    array of indexes to quant_centroid_tab
 123  * @param subband_coef_sign     use random noise instead of predetermined value
 124  * @param mlt_ptr               pointer to the mlt coefficients
 125  */
 126 static void scalar_dequant_math(COOKContext *q, int index,
 127                                 int quant_index, int* subband_coef_index,
 128                                 int* subband_coef_sign, REAL_T *mlt_p)
 129 {
 130     /* Num. half bits to right shift */
 131     const int s = 33 - quant_index + av_log2(q->samples_per_channel);
 132     const FIXP *table = quant_tables[s & 1][index];
 133     FIXP f;
 134     int i;
 135
 136     for(i=0 ; i<SUBBAND_SIZE ; i++) {
 137         f = table[subband_coef_index[i]];
 138         /* noise coding if subband_coef_index[i] == 0 */
 139         if (((subband_coef_index[i] == 0) && cook_random(q)) ||
 140             ((subband_coef_index[i] != 0) && subband_coef_sign[i]))
 141             f = -f;
 142
 143         mlt_p[i] = (s >= 64) ? 0 : fixp_pow2(f, -(s/2));
 144     }
 145 }
 146
 147 #ifdef TEST
 148 /**
 149  * The modulated lapped transform, this takes transform coefficients
 150  * and transforms them into timedomain samples.
 151  * A window step is also included.
 152  *
 153  * @param q                 pointer to the COOKContext
 154  * @param inbuffer          pointer to the mltcoefficients
 155  * @param outbuffer         pointer to the timedomain buffer
 156  * @param mlt_tmp           pointer to temporary storage space
 157  */
 158 #include "cook_fixp_mdct.h"
 159
 160 static inline void imlt_math(COOKContext *q, FIXP *in)
 161 {
 162     const int n = q->samples_per_channel;
 163     const int step = 4 << (10 - av_log2(n));
 164     int i = 0, j = step>>1;
 165
 166     cook_mdct_backward(2 * n, in, q->mono_mdct_output);
 167
 168     do {
 169         FIXP tmp = q->mono_mdct_output[i];
 170
 171         q->mono_mdct_output[i] =
 172           fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j]);
 173         q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j+1]);
 174         j += step;
 175     } while (++i < n/2);
 176     do {
 177         FIXP tmp = q->mono_mdct_output[i];
 178
 179         j -= step;
 180         q->mono_mdct_output[i] =
 181           fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j+1]);
 182         q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j]);
 183     } while (++i < n);
 184 }
 185 #else
 186 #include <codecs/lib/codeclib.h>
 187
 188 static inline void imlt_math(COOKContext *q, FIXP *in)
 189 {
 190     const int n = q->samples_per_channel;
 191     const int step = 4 << (10 - av_log2(n));
 192     int i = 0, j = step>>1;
 193
 194     mdct_backward(2 * n, in, q->mono_mdct_output);
 195
 196     do {
 197         FIXP tmp = q->mono_mdct_output[i];
 198
 199         q->mono_mdct_output[i] =
 200           fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j]);
 201         q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j+1]);
 202         j += step;
 203     } while (++i < n/2);
 204     do {
 205         FIXP tmp = q->mono_mdct_output[i];
 206
 207         j -= step;
 208         q->mono_mdct_output[i] =
 209           fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j+1]);
 210         q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j]);
 211     } while (++i < n);
 212 }
 213 #endif
 214
 215 /**
 216  * Perform buffer overlapping.
 217  *
 218  * @param q                 pointer to the COOKContext
 219  * @param gain              gain correction to apply first to output buffer
 220  * @param buffer            data to overlap
 221  */
 222 static inline void overlap_math(COOKContext *q, int gain, FIXP buffer[])
 223 {
 224     int i;
 225     for(i=0 ; i<q->samples_per_channel ; i++) {
 226         q->mono_mdct_output[i] =
 227           fixp_pow2(q->mono_mdct_output[i], gain) + buffer[i];
 228     }
 229 }
 230
 231
 232 /**
 233  * the actual requantization of the timedomain samples
 234  *
 235  * @param q                 pointer to the COOKContext
 236  * @param buffer            pointer to the timedomain buffer
 237  * @param gain_index        index for the block multiplier
 238  * @param gain_index_next   index for the next block multiplier
 239  */
 240 static inline void
 241 interpolate_math(COOKContext *q, FIXP* buffer,
 242                  int gain_index, int gain_index_next)
 243 {
 244     int i;
 245     int gain_size_factor = q->samples_per_channel / 8;
 246
 247     if(gain_index == gain_index_next){              //static gain
 248         for(i = 0; i < gain_size_factor; i++) {
 249             buffer[i] = fixp_pow2(buffer[i], gain_index);
 250         }
 251     } else {                                        //smooth gain
 252         int step = (gain_index_next - gain_index)
 253                    << (7 - av_log2(gain_size_factor));
 254         int x = 0;
 255
 256         for(i = 0; i < gain_size_factor; i++) {
 257             buffer[i] = fixp_mult_su(buffer[i], pow128_tab[x]);
 258             buffer[i] = fixp_pow2(buffer[i], gain_index+1);
 259
 260             x += step;
 261             gain_index += (x + 128) / 128 - 1;
 262             x = (x + 128) % 128;
 263         }
 264     }
 265 }
 266
 267
 268 /**
 269  * Decoupling calculation for joint stereo coefficients.
 270  *
 271  * @param x                 mono coefficient
 272  * @param table             number of decoupling table
 273  * @param i                 table index
 274  */
 275 static inline FIXP cplscale_math(FIXP x, int table, int i)
 276 {
 277   return fixp_mult_su(x, cplscales[table-2][i]);
 278 }
 279
 280
 281 /**
 282  * Final converion from floating point values to
 283  * signed, 16 bit sound samples. Round and clip.
 284  *
 285  * @param q                 pointer to the COOKContext
 286  * @param out               pointer to the output buffer
 287  * @param chan              0: left or single channel, 1: right channel
 288  */
 289 static inline void output_math(COOKContext *q, int16_t *out, int chan)
 290 {
 291     int j;
 292
 293     for (j = 0; j < q->samples_per_channel; j++) {
 294         out[chan + q->nb_channels * j] = fixp_pow2(q->mono_mdct_output[j], -11);
 295     }
 296 }