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_fixpoint.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 #ifdef ROCKBOX
  39 /* get definitions of MULT31, MULT31_SHIFT15, vect_add, from codelib */
  40 #include "asm_arm.h"
  41 #include "asm_mcf5249.h"
  42 #include "codeclib_misc.h"
  43 #include "codeclib.h"
  44 #endif
  45
  46 /* cplscales was moved from cookdata_fixpoint.h since only   *
  47  * cook_fixpoint.h should see/use it.                        */
  48 static const FIXPU* cplscales[5] = {
  49     cplscale2, cplscale3, cplscale4, cplscale5, cplscale6
  50 };
  51
  52 /**
  53  * Fixed point multiply by power of two.
  54  *
  55  * @param x                     fix point value
  56  * @param i                     integer power-of-two, -31..+31
  57  */
  58 static inline FIXP fixp_pow2(FIXP x, int i)
  59 {
  60   if (i < 0)
  61     return (x >> -i);
  62   else
  63     return x << i;              /* no check for overflow */
  64 }
  65
  66 /**
  67  * Fixed point multiply by fraction.
  68  *
  69  * @param a                     fix point value
  70  * @param b                     fix point fraction, 0 <= b < 1
  71  */
  72 #ifdef ROCKBOX
  73 #define fixp_mult_su(x,y) (MULT31_SHIFT15(x,y))
  74 #else
  75 static inline FIXP fixp_mult_su(FIXP a, FIXPU b)
  76 {
  77     int32_t hb = (a >> 16) * b;
  78     uint32_t lb = (a & 0xffff) * b;
  79
  80     return hb + (lb >> 16) + ((lb & 0x8000) >> 15);
  81 }
  82 #endif
  83
  84 /* Faster version of the above using 32x32=64 bit multiply */
  85 #ifdef ROCKBOX
  86 #define fixmul31(x,y) (MULT31(x,y))
  87 #else
  88 static inline int32_t fixmul31(int32_t x, int32_t y)
  89 {
  90     int64_t temp;
  91
  92     temp = x;
  93     temp *= y;
  94
  95     temp >>= 31;        //16+31-16 = 31 bits
  96
  97     return (int32_t)temp;
  98 }
  99 #endif
 100
 101 /**
 102  * Clips a signed integer value into the amin-amax range.
 103  * @param a value to clip
 104  * @param amin minimum value of the clip range
 105  * @param amax maximum value of the clip range
 106  * @return clipped value
 107  */
 108 static inline int av_clip(int a, int amin, int amax)
 109 {
 110     if      (a < amin) return amin;
 111     else if (a > amax) return amax;
 112     else               return a;
 113 }
 114
 115 /**
 116  * The real requantization of the mltcoefs
 117  *
 118  * @param q                     pointer to the COOKContext
 119  * @param index                 index
 120  * @param quant_index           quantisation index for this band
 121  * @param subband_coef_index    array of indexes to quant_centroid_tab
 122  * @param subband_coef_sign     use random noise instead of predetermined value
 123  * @param mlt_ptr               pointer to the mlt coefficients
 124  */
 125 static void scalar_dequant_math(COOKContext *q, int index,
 126                                 int quant_index, int* subband_coef_index,
 127                                 int* subband_coef_sign, REAL_T *mlt_p)
 128 {
 129     /* Num. half bits to right shift */
 130     const int s = (33 - quant_index + av_log2(q->samples_per_channel)) >> 1;
 131     const FIXP *table = quant_tables[s & 1][index];
 132     FIXP f;
 133     int i;
 134
 135
 136     if(s >= 32)
 137         memset(mlt_p, 0, sizeof(REAL_T)*SUBBAND_SIZE);
 138     else
 139     {
 140         for(i=0 ; i<SUBBAND_SIZE ; i++) {
 141             f = (table[subband_coef_index[i]])>>s;
 142             /* noise coding if subband_coef_index[i] == 0 */
 143             if (((subband_coef_index[i] == 0) && cook_random(q)) ||
 144                 ((subband_coef_index[i] != 0) && subband_coef_sign[i]))
 145                 f = -f;
 146
 147             *mlt_p++ = f;
 148         }
 149     }
 150 }
 151
 152 /**
 153  * The modulated lapped transform, this takes transform coefficients
 154  * and transforms them into timedomain samples.
 155  * A window step is also included.
 156  *
 157  * @param q                 pointer to the COOKContext
 158  * @param inbuffer          pointer to the mltcoefficients
 159  * @param outbuffer         pointer to the timedomain buffer
 160  * @param mlt_tmp           pointer to temporary storage space
 161  */
 162 #include "../lib/mdct_lookup.h"
 163
 164 void imlt_math(COOKContext *q, FIXP *in) ICODE_ATTR;
 165 void imlt_math(COOKContext *q, FIXP *in)
 166 {
 167     const int n = q->samples_per_channel;
 168     const int step = 2 << (10 - av_log2(n));
 169     REAL_T *mdct_out = q->mono_mdct_output;
 170     REAL_T tmp;
 171     int i = 0, j = 0;
 172
 173     ff_imdct_calc(q->mdct_nbits, q->mono_mdct_output, in);
 174
 175     do {
 176         tmp = mdct_out[i];
 177         mdct_out[i  ] = fixmul31(-mdct_out[n+i], (sincos_lookup0[j  ]));
 178         mdct_out[n+i] = fixmul31(tmp           , (sincos_lookup0[j+1]));
 179
 180         j += step;
 181     } while (++i < n/2);
 182
 183     do {
 184         j -= step;
 185
 186         tmp = mdct_out[i];
 187         mdct_out[i  ] = fixmul31(-mdct_out[n+i], (sincos_lookup0[j+1]));
 188         mdct_out[n+i] = fixmul31(tmp           , (sincos_lookup0[j  ]));
 189     } while (++i < n);
 190 }
 191
 192 /**
 193  * Perform buffer overlapping.
 194  *
 195  * @param q                 pointer to the COOKContext
 196  * @param gain              gain correction to apply first to output buffer
 197  * @param buffer            data to overlap
 198  */
 199 void overlap_math(COOKContext *q, int gain, FIXP buffer[]) ICODE_ATTR;
 200 void overlap_math(COOKContext *q, int gain, FIXP buffer[])
 201 {
 202     int i;
 203 #ifdef ROCKBOX
 204     if(LIKELY(gain == 0))
 205     {
 206         vect_add(q->mono_mdct_output, buffer, q->samples_per_channel);
 207
 208     } else if (gain > 0){
 209         for(i=0 ; i<q->samples_per_channel ; i++) {
 210             q->mono_mdct_output[i] = (q->mono_mdct_output[i]<< gain) + buffer[i];        }
 211
 212     } else {
 213         for(i=0 ; i<q->samples_per_channel ; i++) {
 214             q->mono_mdct_output[i] = (q->mono_mdct_output[i]>>-gain) + buffer[i];
 215         }
 216     }
 217 #else
 218     for(i=0 ; i<q->samples_per_channel ; i++) {
 219         q->mono_mdct_output[i] =
 220           fixp_pow2(q->mono_mdct_output[i], gain) + buffer[i];
 221     }
 222 #endif
 223 }
 224
 225
 226 /**
 227  * the actual requantization of the timedomain samples
 228  *
 229  * @param q                 pointer to the COOKContext
 230  * @param buffer            pointer to the timedomain buffer
 231  * @param gain_index        index for the block multiplier
 232  * @param gain_index_next   index for the next block multiplier
 233  */
 234 static inline void
 235 interpolate_math(COOKContext *q, register FIXP* buffer,
 236                  int gain_index, int gain_index_next)
 237 {
 238     int i;
 239     int gain_size_factor = q->samples_per_channel / 8;
 240
 241     if(gain_index == gain_index_next){              //static gain
 242         for(i = 0; i < gain_size_factor; i++) {
 243             buffer[i] = fixp_pow2(buffer[i], gain_index);
 244         }
 245     } else {                                        //smooth gain
 246         int step = (gain_index_next - gain_index)
 247                    << (7 - av_log2(gain_size_factor));
 248         int x = 0;
 249         register FIXP* bufferend = buffer+gain_size_factor;
 250         while(buffer < bufferend )
 251         {
 252             *buffer = fixp_pow2(
 253                           fixp_mult_su(*buffer, pow128_tab[x]),
 254                           gain_index+1);
 255             buffer++;
 256
 257             x += step;
 258             gain_index += ( (x + 128) >> 7 ) - 1;
 259             x = ( (x + 128) & 127 );
 260         }
 261     }
 262 }
 263
 264
 265 /**
 266  * Decoupling calculation for joint stereo coefficients.
 267  *
 268  * @param x                 mono coefficient
 269  * @param table             number of decoupling table
 270  * @param i                 table index
 271  */
 272 static inline FIXP cplscale_math(FIXP x, int table, int i)
 273 {
 274   return fixp_mult_su(x, cplscales[table-2][i]);
 275 }