libFDK/src/arm/fft_rad2_arm.cpp

   1
   2 /* -----------------------------------------------------------------------------------------------------------
   3 Software License for The Fraunhofer FDK AAC Codec Library for Android
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  10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
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  73 5.    CONTACT INFORMATION
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  75 Fraunhofer Institute for Integrated Circuits IIS
  76 Attention: Audio and Multimedia Departments - FDK AAC LL
  77 Am Wolfsmantel 33
  78 91058 Erlangen, Germany
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  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /***************************  Fraunhofer IIS FDK Tools  **********************
  85
  86    Author(s):
  87    Description: dit_fft ARM assembler replacements.
  88
  89 ******************************************************************************/
  90
  91 /* NEON optimized FFT currently builds only with RVCT toolchain */
  92
  93 #ifndef FUNCTION_dit_fft
  94
  95 /* If dit_fft was not yet defined by ARM-Cortex ... */
  96
  97 #if defined(SINETABLE_16BIT)
  98
  99 #define FUNCTION_dit_fft
 100
 101 /*****************************************************************************
 102
 103    date:   28.07.2005   srl
 104
 105    Contents/description: dit-tukey-FFT-algorithm
 106
 107 ******************************************************************************/
 108
 109 #if defined(FUNCTION_dit_fft)
 110
 111
 112 void dit_fft(FIXP_DBL *x, const INT ldn, const FIXP_STP *trigdata, const INT trigDataSize)
 113 {
 114     const INT n=1<<ldn;
 115     INT i;
 116
 117     scramble(x,n);
 118     /*
 119      * 1+2 stage radix 4
 120      */
 121
 122     for (i=0;i<n*2;i+=8)
 123     {
 124       FIXP_DBL a00, a10, a20, a30;
 125       a00 = (x[i + 0] + x[i + 2])>>1;  /* Re A + Re B */
 126       a10 = (x[i + 4] + x[i + 6])>>1;  /* Re C + Re D */
 127       a20 = (x[i + 1] + x[i + 3])>>1;  /* Im A + Im B */
 128       a30 = (x[i + 5] + x[i + 7])>>1;  /* Im C + Im D */
 129
 130       x[i + 0] = a00 + a10;       /* Re A' = Re A + Re B + Re C + Re D */
 131       x[i + 4] = a00 - a10;       /* Re C' = Re A + Re B - Re C - Re D */
 132       x[i + 1] = a20 + a30;       /* Im A' = Im A + Im B + Im C + Im D */
 133       x[i + 5] = a20 - a30;       /* Im C' = Im A + Im B - Im C - Im D */
 134
 135       a00 = a00 - x[i + 2];       /* Re A - Re B */
 136       a10 = a10 - x[i + 6];       /* Re C - Re D */
 137       a20 = a20 - x[i + 3];       /* Im A - Im B */
 138       a30 = a30 - x[i + 7];       /* Im C - Im D */
 139
 140       x[i + 2] = a00 + a30;       /* Re B' = Re A - Re B + Im C - Im D */
 141       x[i + 6] = a00 - a30;       /* Re D' = Re A - Re B - Im C + Im D */
 142       x[i + 3] = a20 - a10;       /* Im B' = Im A - Im B - Re C + Re D */
 143       x[i + 7] = a20 + a10;       /* Im D' = Im A - Im B + Re C - Re D */
 144     }
 145
 146     INT mh = 1 << 1;
 147     INT ldm = ldn - 2;
 148     INT trigstep = trigDataSize;
 149
 150     do
 151     {
 152         const FIXP_STP *pTrigData = trigdata;
 153         INT j;
 154
 155         mh <<= 1;
 156         trigstep >>= 1;
 157
 158         FDK_ASSERT(trigstep > 0);
 159
 160         /* Do first iteration with c=1.0 and s=0.0 separately to avoid loosing to much precision.
 161            Beware: The impact on the overal FFT precision is rather large. */
 162         {
 163             FIXP_DBL *xt1 = x;
 164             int r = n;
 165
 166             do {
 167                 FIXP_DBL *xt2 = xt1 + (mh<<1);
 168                 /*
 169                 FIXP_DBL *xt1 = x+ ((r)<<1);
 170                 FIXP_DBL *xt2 = xt1 + (mh<<1);
 171                 */
 172                 FIXP_DBL vr,vi,ur,ui;
 173
 174                 //cplxMultDiv2(&vi, &vr, x[t2+1], x[t2], (FIXP_SGL)1.0, (FIXP_SGL)0.0);
 175                 vi = xt2[1]>>1;
 176                 vr = xt2[0]>>1;
 177
 178                 ur = xt1[0]>>1;
 179                 ui = xt1[1]>>1;
 180
 181                 xt1[0] = ur+vr;
 182                 xt1[1] = ui+vi;
 183
 184                 xt2[0] = ur-vr;
 185                 xt2[1] = ui-vi;
 186
 187                 xt1 += mh;
 188                 xt2 += mh;
 189
 190                 //cplxMultDiv2(&vr, &vi, x[t2+1], x[t2], (FIXP_SGL)1.0, (FIXP_SGL)0.0);
 191                 vr = xt2[1]>>1;
 192                 vi = xt2[0]>>1;
 193
 194                 ur = xt1[0]>>1;
 195                 ui = xt1[1]>>1;
 196
 197                 xt1[0] = ur+vr;
 198                 xt1[1] = ui-vi;
 199
 200                 xt2[0] = ur-vr;
 201                 xt2[1] = ui+vi;
 202
 203                 xt1 = xt2 + mh;
 204             } while ((r=r-(mh<<1)) != 0);
 205         }
 206         for(j=4; j<mh; j+=4)
 207         {
 208             FIXP_DBL *xt1 = x + (j>>1);
 209             FIXP_SPK cs;
 210             int r = n;
 211
 212             pTrigData += trigstep;
 213             cs = *pTrigData;
 214
 215             do
 216             {
 217                 FIXP_DBL *xt2 = xt1 + (mh<<1);
 218                 FIXP_DBL vr,vi,ur,ui;
 219
 220                 cplxMultDiv2(&vi, &vr, xt2[1], xt2[0], cs);
 221
 222                 ur = xt1[0]>>1;
 223                 ui = xt1[1]>>1;
 224
 225                 xt1[0] = ur+vr;
 226                 xt1[1] = ui+vi;
 227
 228                 xt2[0] = ur-vr;
 229                 xt2[1] = ui-vi;
 230
 231                 xt1 += mh;
 232                 xt2 += mh;
 233
 234                 cplxMultDiv2(&vr, &vi, xt2[1], xt2[0], cs);
 235
 236                 ur = xt1[0]>>1;
 237                 ui = xt1[1]>>1;
 238
 239                 xt1[0] = ur+vr;
 240                 xt1[1] = ui-vi;
 241
 242                 xt2[0] = ur-vr;
 243                 xt2[1] = ui+vi;
 244
 245                 /* Same as above but for t1,t2 with j>mh/4 and thus cs swapped */
 246                 xt1 = xt1 - (j);
 247                 xt2 = xt1 + (mh<<1);
 248
 249                 cplxMultDiv2(&vi, &vr, xt2[0], xt2[1], cs);
 250
 251                 ur = xt1[0]>>1;
 252                 ui = xt1[1]>>1;
 253
 254                 xt1[0] = ur+vr;
 255                 xt1[1] = ui-vi;
 256
 257                 xt2[0] = ur-vr;
 258                 xt2[1] = ui+vi;
 259
 260                 xt1 += mh;
 261                 xt2 += mh;
 262
 263                 cplxMultDiv2(&vr, &vi, xt2[0], xt2[1], cs);
 264
 265                 ur = xt1[0]>>1;
 266                 ui = xt1[1]>>1;
 267
 268                 xt1[0] = ur-vr;
 269                 xt1[1] = ui-vi;
 270
 271                 xt2[0] = ur+vr;
 272                 xt2[1] = ui+vi;
 273
 274                 xt1 = xt2 + (j);
 275             }  while ((r=r-(mh<<1)) != 0);
 276         }
 277         {
 278             FIXP_DBL *xt1 = x + (mh>>1);
 279             int r = n;
 280
 281             do
 282             {
 283                 FIXP_DBL *xt2 = xt1 + (mh<<1);
 284                 FIXP_DBL vr,vi,ur,ui;
 285
 286                 cplxMultDiv2(&vi, &vr, xt2[1], xt2[0], STC(0x5a82799a), STC(0x5a82799a));
 287
 288                 ur = xt1[0]>>1;
 289                 ui = xt1[1]>>1;
 290
 291                 xt1[0] = ur+vr;
 292                 xt1[1] = ui+vi;
 293
 294                 xt2[0] = ur-vr;
 295                 xt2[1] = ui-vi;
 296
 297                 xt1 += mh;
 298                 xt2 += mh;
 299
 300                 cplxMultDiv2(&vr, &vi, xt2[1], xt2[0], STC(0x5a82799a), STC(0x5a82799a));
 301
 302                 ur = xt1[0]>>1;
 303                 ui = xt1[1]>>1;
 304
 305                 xt1[0] = ur+vr;
 306                 xt1[1] = ui-vi;
 307
 308                 xt2[0] = ur-vr;
 309                 xt2[1] = ui+vi;
 310
 311                 xt1 = xt2 + mh;
 312             }  while ((r=r-(mh<<1)) != 0);
 313         }
 314     } while (--ldm != 0);
 315 }
 316
 317 #endif /* if defined(FUNCTION_dit_fft)  */
 318
 319 #endif /* if defined(SINETABLE_16BIT) */
 320
 321 #endif /* ifndef FUNCTION_dit_fft */