tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_fir_interpolate_q15.c

   1 /*-----------------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_fir_interpolate_q15.c
   9 *
  10 * Description:  Q15 FIR interpolation.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * ---------------------------------------------------------------------------*/
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupFilters
  45  */
  46
  47 /**
  48  * @addtogroup FIR_Interpolate
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Processing function for the Q15 FIR interpolator.
  54  * @param[in] *S        points to an instance of the Q15 FIR interpolator structure.
  55  * @param[in] *pSrc     points to the block of input data.
  56  * @param[out] *pDst    points to the block of output data.
  57  * @param[in] blockSize number of input samples to process per call.
  58  * @return none.
  59  *
  60  * <b>Scaling and Overflow Behavior:</b>
  61  * \par
  62  * The function is implemented using a 64-bit internal accumulator.
  63  * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
  64  * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
  65  * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
  66  * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
  67  * Lastly, the accumulator is saturated to yield a result in 1.15 format.
  68  */
  69
  70 #ifndef ARM_MATH_CM0_FAMILY
  71
  72   /* Run the below code for Cortex-M4 and Cortex-M3 */
  73
  74 void arm_fir_interpolate_q15(
  75   const arm_fir_interpolate_instance_q15 * S,
  76   q15_t * pSrc,
  77   q15_t * pDst,
  78   uint32_t blockSize)
  79 {
  80   q15_t *pState = S->pState;                     /* State pointer                                            */
  81   q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
  82   q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
  83   q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
  84   q63_t sum0;                                    /* Accumulators                                             */
  85   q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
  86   uint32_t i, blkCnt, j, tapCnt;                 /* Loop counters                                            */
  87   uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */
  88   uint32_t blkCntN2;
  89   q63_t acc0, acc1;
  90   q15_t x1;
  91
  92   /* S->pState buffer contains previous frame (phaseLen - 1) samples */
  93   /* pStateCurnt points to the location where the new input data should be written */
  94   pStateCurnt = S->pState + ((q31_t) phaseLen - 1);
  95
  96   /* Initialise  blkCnt */
  97   blkCnt = blockSize / 2;
  98   blkCntN2 = blockSize - (2 * blkCnt);
  99
 100   /* Samples loop unrolled by 2 */
 101   while(blkCnt > 0u)
 102   {
 103     /* Copy new input sample into the state buffer */
 104     *pStateCurnt++ = *pSrc++;
 105     *pStateCurnt++ = *pSrc++;
 106
 107     /* Address modifier index of coefficient buffer */
 108     j = 1u;
 109
 110     /* Loop over the Interpolation factor. */
 111     i = (S->L);
 112
 113     while(i > 0u)
 114     {
 115       /* Set accumulator to zero */
 116       acc0 = 0;
 117       acc1 = 0;
 118
 119       /* Initialize state pointer */
 120       ptr1 = pState;
 121
 122       /* Initialize coefficient pointer */
 123       ptr2 = pCoeffs + (S->L - j);
 124
 125       /* Loop over the polyPhase length. Unroll by a factor of 4.
 126        ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
 127       tapCnt = phaseLen >> 2u;
 128
 129       x0 = *(ptr1++);
 130
 131       while(tapCnt > 0u)
 132       {
 133
 134         /* Read the input sample */
 135         x1 = *(ptr1++);
 136
 137         /* Read the coefficient */
 138         c0 = *(ptr2);
 139
 140         /* Perform the multiply-accumulate */
 141         acc0 += (q63_t) x0 *c0;
 142         acc1 += (q63_t) x1 *c0;
 143
 144
 145         /* Read the coefficient */
 146         c0 = *(ptr2 + S->L);
 147
 148         /* Read the input sample */
 149         x0 = *(ptr1++);
 150
 151         /* Perform the multiply-accumulate */
 152         acc0 += (q63_t) x1 *c0;
 153         acc1 += (q63_t) x0 *c0;
 154
 155
 156         /* Read the coefficient */
 157         c0 = *(ptr2 + S->L * 2);
 158
 159         /* Read the input sample */
 160         x1 = *(ptr1++);
 161
 162         /* Perform the multiply-accumulate */
 163         acc0 += (q63_t) x0 *c0;
 164         acc1 += (q63_t) x1 *c0;
 165
 166         /* Read the coefficient */
 167         c0 = *(ptr2 + S->L * 3);
 168
 169         /* Read the input sample */
 170         x0 = *(ptr1++);
 171
 172         /* Perform the multiply-accumulate */
 173         acc0 += (q63_t) x1 *c0;
 174         acc1 += (q63_t) x0 *c0;
 175
 176
 177         /* Upsampling is done by stuffing L-1 zeros between each sample.
 178          * So instead of multiplying zeros with coefficients,
 179          * Increment the coefficient pointer by interpolation factor times. */
 180         ptr2 += 4 * S->L;
 181
 182         /* Decrement the loop counter */
 183         tapCnt--;
 184       }
 185
 186       /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
 187       tapCnt = phaseLen % 0x4u;
 188
 189       while(tapCnt > 0u)
 190       {
 191
 192         /* Read the input sample */
 193         x1 = *(ptr1++);
 194
 195         /* Read the coefficient */
 196         c0 = *(ptr2);
 197
 198         /* Perform the multiply-accumulate */
 199         acc0 += (q63_t) x0 *c0;
 200         acc1 += (q63_t) x1 *c0;
 201
 202         /* Increment the coefficient pointer by interpolation factor times. */
 203         ptr2 += S->L;
 204
 205         /* update states for next sample processing */
 206         x0 = x1;
 207
 208         /* Decrement the loop counter */
 209         tapCnt--;
 210       }
 211
 212       /* The result is in the accumulator, store in the destination buffer. */
 213       *pDst = (q15_t) (__SSAT((acc0 >> 15), 16));
 214       *(pDst + S->L) = (q15_t) (__SSAT((acc1 >> 15), 16));
 215
 216       pDst++;
 217
 218       /* Increment the address modifier index of coefficient buffer */
 219       j++;
 220
 221       /* Decrement the loop counter */
 222       i--;
 223     }
 224
 225     /* Advance the state pointer by 1
 226      * to process the next group of interpolation factor number samples */
 227     pState = pState + 2;
 228
 229     pDst += S->L;
 230
 231     /* Decrement the loop counter */
 232     blkCnt--;
 233   }
 234
 235   /* If the blockSize is not a multiple of 2, compute any remaining output samples here.
 236    ** No loop unrolling is used. */
 237   blkCnt = blkCntN2;
 238
 239   /* Loop over the blockSize. */
 240   while(blkCnt > 0u)
 241   {
 242     /* Copy new input sample into the state buffer */
 243     *pStateCurnt++ = *pSrc++;
 244
 245     /* Address modifier index of coefficient buffer */
 246     j = 1u;
 247
 248     /* Loop over the Interpolation factor. */
 249     i = S->L;
 250     while(i > 0u)
 251     {
 252       /* Set accumulator to zero */
 253       sum0 = 0;
 254
 255       /* Initialize state pointer */
 256       ptr1 = pState;
 257
 258       /* Initialize coefficient pointer */
 259       ptr2 = pCoeffs + (S->L - j);
 260
 261       /* Loop over the polyPhase length. Unroll by a factor of 4.
 262        ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
 263       tapCnt = phaseLen >> 2;
 264       while(tapCnt > 0u)
 265       {
 266
 267         /* Read the coefficient */
 268         c0 = *(ptr2);
 269
 270         /* Upsampling is done by stuffing L-1 zeros between each sample.
 271          * So instead of multiplying zeros with coefficients,
 272          * Increment the coefficient pointer by interpolation factor times. */
 273         ptr2 += S->L;
 274
 275         /* Read the input sample */
 276         x0 = *(ptr1++);
 277
 278         /* Perform the multiply-accumulate */
 279         sum0 += (q63_t) x0 *c0;
 280
 281         /* Read the coefficient */
 282         c0 = *(ptr2);
 283
 284         /* Increment the coefficient pointer by interpolation factor times. */
 285         ptr2 += S->L;
 286
 287         /* Read the input sample */
 288         x0 = *(ptr1++);
 289
 290         /* Perform the multiply-accumulate */
 291         sum0 += (q63_t) x0 *c0;
 292
 293         /* Read the coefficient */
 294         c0 = *(ptr2);
 295
 296         /* Increment the coefficient pointer by interpolation factor times. */
 297         ptr2 += S->L;
 298
 299         /* Read the input sample */
 300         x0 = *(ptr1++);
 301
 302         /* Perform the multiply-accumulate */
 303         sum0 += (q63_t) x0 *c0;
 304
 305         /* Read the coefficient */
 306         c0 = *(ptr2);
 307
 308         /* Increment the coefficient pointer by interpolation factor times. */
 309         ptr2 += S->L;
 310
 311         /* Read the input sample */
 312         x0 = *(ptr1++);
 313
 314         /* Perform the multiply-accumulate */
 315         sum0 += (q63_t) x0 *c0;
 316
 317         /* Decrement the loop counter */
 318         tapCnt--;
 319       }
 320
 321       /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
 322       tapCnt = phaseLen & 0x3u;
 323
 324       while(tapCnt > 0u)
 325       {
 326         /* Read the coefficient */
 327         c0 = *(ptr2);
 328
 329         /* Increment the coefficient pointer by interpolation factor times. */
 330         ptr2 += S->L;
 331
 332         /* Read the input sample */
 333         x0 = *(ptr1++);
 334
 335         /* Perform the multiply-accumulate */
 336         sum0 += (q63_t) x0 *c0;
 337
 338         /* Decrement the loop counter */
 339         tapCnt--;
 340       }
 341
 342       /* The result is in the accumulator, store in the destination buffer. */
 343       *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16));
 344
 345       j++;
 346
 347       /* Decrement the loop counter */
 348       i--;
 349     }
 350
 351     /* Advance the state pointer by 1
 352      * to process the next group of interpolation factor number samples */
 353     pState = pState + 1;
 354
 355     /* Decrement the loop counter */
 356     blkCnt--;
 357   }
 358
 359
 360   /* Processing is complete.
 361    ** Now copy the last phaseLen - 1 samples to the satrt of the state buffer.
 362    ** This prepares the state buffer for the next function call. */
 363
 364   /* Points to the start of the state buffer */
 365   pStateCurnt = S->pState;
 366
 367   i = ((uint32_t) phaseLen - 1u) >> 2u;
 368
 369   /* copy data */
 370   while(i > 0u)
 371   {
 372 #ifndef UNALIGNED_SUPPORT_DISABLE
 373
 374     *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
 375     *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
 376
 377 #else
 378
 379     *pStateCurnt++ = *pState++;
 380         *pStateCurnt++ = *pState++;
 381         *pStateCurnt++ = *pState++;
 382         *pStateCurnt++ = *pState++;
 383
 384 #endif  /*      #ifndef UNALIGNED_SUPPORT_DISABLE       */
 385
 386         /* Decrement the loop counter */
 387     i--;
 388   }
 389
 390   i = ((uint32_t) phaseLen - 1u) % 0x04u;
 391
 392   while(i > 0u)
 393   {
 394     *pStateCurnt++ = *pState++;
 395
 396     /* Decrement the loop counter */
 397     i--;
 398   }
 399 }
 400
 401 #else
 402
 403   /* Run the below code for Cortex-M0 */
 404
 405 void arm_fir_interpolate_q15(
 406   const arm_fir_interpolate_instance_q15 * S,
 407   q15_t * pSrc,
 408   q15_t * pDst,
 409   uint32_t blockSize)
 410 {
 411   q15_t *pState = S->pState;                     /* State pointer                                            */
 412   q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
 413   q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
 414   q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
 415   q63_t sum;                                     /* Accumulator */
 416   q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
 417   uint32_t i, blkCnt, tapCnt;                    /* Loop counters                                            */
 418   uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */
 419
 420
 421   /* S->pState buffer contains previous frame (phaseLen - 1) samples */
 422   /* pStateCurnt points to the location where the new input data should be written */
 423   pStateCurnt = S->pState + (phaseLen - 1u);
 424
 425   /* Total number of intput samples */
 426   blkCnt = blockSize;
 427
 428   /* Loop over the blockSize. */
 429   while(blkCnt > 0u)
 430   {
 431     /* Copy new input sample into the state buffer */
 432     *pStateCurnt++ = *pSrc++;
 433
 434     /* Loop over the Interpolation factor. */
 435     i = S->L;
 436
 437     while(i > 0u)
 438     {
 439       /* Set accumulator to zero */
 440       sum = 0;
 441
 442       /* Initialize state pointer */
 443       ptr1 = pState;
 444
 445       /* Initialize coefficient pointer */
 446       ptr2 = pCoeffs + (i - 1u);
 447
 448       /* Loop over the polyPhase length */
 449       tapCnt = (uint32_t) phaseLen;
 450
 451       while(tapCnt > 0u)
 452       {
 453         /* Read the coefficient */
 454         c0 = *ptr2;
 455
 456         /* Increment the coefficient pointer by interpolation factor times. */
 457         ptr2 += S->L;
 458
 459         /* Read the input sample */
 460         x0 = *ptr1++;
 461
 462         /* Perform the multiply-accumulate */
 463         sum += ((q31_t) x0 * c0);
 464
 465         /* Decrement the loop counter */
 466         tapCnt--;
 467       }
 468
 469       /* Store the result after converting to 1.15 format in the destination buffer */
 470       *pDst++ = (q15_t) (__SSAT((sum >> 15), 16));
 471
 472       /* Decrement the loop counter */
 473       i--;
 474     }
 475
 476     /* Advance the state pointer by 1
 477      * to process the next group of interpolation factor number samples */
 478     pState = pState + 1;
 479
 480     /* Decrement the loop counter */
 481     blkCnt--;
 482   }
 483
 484   /* Processing is complete.
 485    ** Now copy the last phaseLen - 1 samples to the start of the state buffer.
 486    ** This prepares the state buffer for the next function call. */
 487
 488   /* Points to the start of the state buffer */
 489   pStateCurnt = S->pState;
 490
 491   i = (uint32_t) phaseLen - 1u;
 492
 493   while(i > 0u)
 494   {
 495     *pStateCurnt++ = *pState++;
 496
 497     /* Decrement the loop counter */
 498     i--;
 499   }
 500
 501 }
 502
 503 #endif /*   #ifndef ARM_MATH_CM0_FAMILY */
 504
 505
 506  /**
 507   * @} end of FIR_Interpolate group
 508   */