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  * Initialise fixed point implementation.
  58  * Nothing to do for fixed point.
  59  *
  60  * @param q                     pointer to the COOKContext
  61  */
  62 static inline int init_cook_math(COOKContext *q)
  63 {
  64     return 0;
  65 }
  66
  67 /**
  68  * Free resources used by floating point implementation.
  69  * Nothing to do for fixed point.
  70  *
  71  * @param q                     pointer to the COOKContext
  72  */
  73 static inline void free_cook_math(COOKContext *q)
  74 {
  75     return;
  76 }
  77
  78
  79 /**
  80  * Fixed point multiply by power of two.
  81  *
  82  * @param x                     fix point value
  83  * @param i                     integer power-of-two, -31..+31
  84  */
  85 static inline FIXP fixp_pow2(FIXP x, int i)
  86 {
  87   if (i < 0)
  88     return (x >> -i) + ((x >> (-i-1)) & 1);
  89   else
  90     return x << i;              /* no check for overflow */
  91 }
  92
  93 /**
  94  * Fixed point multiply by fraction.
  95  *
  96  * @param a                     fix point value
  97  * @param b                     fix point fraction, 0 <= b < 1
  98  */
  99 static inline FIXP fixp_mult_su(FIXP a, FIXPU b)
 100 {
 101     int32_t hb = (a >> 16) * b;
 102     uint32_t lb = (a & 0xffff) * b;
 103
 104     return hb + (lb >> 16) + ((lb & 0x8000) >> 15);
 105 }
 106
 107 /* math functions taken from libavutil/common.h */
 108
 109 static inline int av_log2(unsigned int v)
 110 {
 111     int n = 0;
 112     if (v & 0xffff0000) {
 113         v >>= 16;
 114         n += 16;
 115     }
 116     if (v & 0xff00) {
 117         v >>= 8;
 118         n += 8;
 119     }
 120     n += ff_log2_tab[v];
 121
 122     return n;
 123 }
 124
 125 /**
 126  * Clips a signed integer value into the amin-amax range.
 127  * @param a value to clip
 128  * @param amin minimum value of the clip range
 129  * @param amax maximum value of the clip range
 130  * @return clipped value
 131  */
 132 static inline int av_clip(int a, int amin, int amax)
 133 {
 134     if      (a < amin) return amin;
 135     else if (a > amax) return amax;
 136     else               return a;
 137 }
 138
 139 /**
 140  * The real requantization of the mltcoefs
 141  *
 142  * @param q                     pointer to the COOKContext
 143  * @param index                 index
 144  * @param quant_index           quantisation index for this band
 145  * @param subband_coef_index    array of indexes to quant_centroid_tab
 146  * @param subband_coef_sign     use random noise instead of predetermined value
 147  * @param mlt_ptr               pointer to the mlt coefficients
 148  */
 149 static void scalar_dequant_math(COOKContext *q, int index,
 150                                 int quant_index, int* subband_coef_index,
 151                                 int* subband_coef_sign, REAL_T *mlt_p)
 152 {
 153     /* Num. half bits to right shift */
 154     const int s = 33 - quant_index + av_log2(q->samples_per_channel);
 155     const FIXP *table = quant_tables[s & 1][index];
 156     FIXP f;
 157     int i;
 158
 159     for(i=0 ; i<SUBBAND_SIZE ; i++) {
 160         f = table[subband_coef_index[i]];
 161         /* noise coding if subband_coef_index[i] == 0 */
 162         if (((subband_coef_index[i] == 0) && cook_random(q)) ||
 163             ((subband_coef_index[i] != 0) && subband_coef_sign[i]))
 164             f = -f;
 165
 166         mlt_p[i] = (s >= 64) ? 0 : fixp_pow2(f, -(s/2));
 167     }
 168 }
 169
 170
 171 /**
 172  * The modulated lapped transform, this takes transform coefficients
 173  * and transforms them into timedomain samples.
 174  * A window step is also included.
 175  *
 176  * @param q                 pointer to the COOKContext
 177  * @param inbuffer          pointer to the mltcoefficients
 178  * @param outbuffer         pointer to the timedomain buffer
 179  * @param mlt_tmp           pointer to temporary storage space
 180  */
 181 #include "cook_fixp_mdct.h"
 182
 183 static inline void imlt_math(COOKContext *q, FIXP *in)
 184 {
 185     const int n = q->samples_per_channel;
 186     const int step = 4 << (10 - av_log2(n));
 187     int i = 0, j = step>>1;
 188
 189     cook_mdct_backward(2 * n, in, q->mono_mdct_output);
 190
 191     do {
 192         FIXP tmp = q->mono_mdct_output[i];
 193
 194         q->mono_mdct_output[i] =
 195           fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j]);
 196         q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j+1]);
 197         j += step;
 198     } while (++i < n/2);
 199     do {
 200         FIXP tmp = q->mono_mdct_output[i];
 201
 202         j -= step;
 203         q->mono_mdct_output[i] =
 204           fixp_mult_su(-q->mono_mdct_output[n + i], sincos_lookup[j+1]);
 205         q->mono_mdct_output[n + i] = fixp_mult_su(tmp, sincos_lookup[j]);
 206     } while (++i < n);
 207 }
 208
 209
 210 /**
 211  * Perform buffer overlapping.
 212  *
 213  * @param q                 pointer to the COOKContext
 214  * @param gain              gain correction to apply first to output buffer
 215  * @param buffer            data to overlap
 216  */
 217 static inline void overlap_math(COOKContext *q, int gain, FIXP buffer[])
 218 {
 219     int i;
 220     for(i=0 ; i<q->samples_per_channel ; i++) {
 221         q->mono_mdct_output[i] =
 222           fixp_pow2(q->mono_mdct_output[i], gain) + buffer[i];
 223     }
 224 }
 225
 226
 227 /**
 228  * the actual requantization of the timedomain samples
 229  *
 230  * @param q                 pointer to the COOKContext
 231  * @param buffer            pointer to the timedomain buffer
 232  * @param gain_index        index for the block multiplier
 233  * @param gain_index_next   index for the next block multiplier
 234  */
 235 static inline void
 236 interpolate_math(COOKContext *q, FIXP* buffer,
 237                  int gain_index, int gain_index_next)
 238 {
 239     int i;
 240     int gain_size_factor = q->samples_per_channel / 8;
 241
 242     if(gain_index == gain_index_next){              //static gain
 243         for(i = 0; i < gain_size_factor; i++) {
 244             buffer[i] = fixp_pow2(buffer[i], gain_index);
 245         }
 246     } else {                                        //smooth gain
 247         int step = (gain_index_next - gain_index)
 248                    << (7 - av_log2(gain_size_factor));
 249         int x = 0;
 250
 251         for(i = 0; i < gain_size_factor; i++) {
 252             buffer[i] = fixp_mult_su(buffer[i], pow128_tab[x]);
 253             buffer[i] = fixp_pow2(buffer[i], gain_index+1);
 254
 255             x += step;
 256             gain_index += (x + 128) / 128 - 1;
 257             x = (x + 128) % 128;
 258         }
 259     }
 260 }
 261
 262
 263 /**
 264  * Decoupling calculation for joint stereo coefficients.
 265  *
 266  * @param x                 mono coefficient
 267  * @param table             number of decoupling table
 268  * @param i                 table index
 269  */
 270 static inline FIXP cplscale_math(FIXP x, int table, int i)
 271 {
 272   return fixp_mult_su(x, cplscales[table-2][i]);
 273 }
 274
 275
 276 /**
 277  * Final converion from floating point values to
 278  * signed, 16 bit sound samples. Round and clip.
 279  *
 280  * @param q                 pointer to the COOKContext
 281  * @param out               pointer to the output buffer
 282  * @param chan              0: left or single channel, 1: right channel
 283  */
 284 static inline void output_math(COOKContext *q, int16_t *out, int chan)
 285 {
 286     int j;
 287
 288     for (j = 0; j < q->samples_per_channel; j++) {
 289         out[chan + q->nb_channels * j] =
 290           av_clip(fixp_pow2(q->mono_mdct_output[j], -11), -32768, 32767);
 291     }
 292 }