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# arm_conv_f32.c

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    00001 /* ----------------------------------------------------------------------------
    00002 * Copyright (C) 2010 ARM Limited. All rights reserved.
    00003 *
    00004 * $Date:        15. July 2011
    00005 * $Revision:    V1.0.10
    00006 *
    00007 * Project:      CMSIS DSP Library
    00008 * Title:        arm_conv_f32.c
    00009 *
    00010 * Description:  Convolution of floating-point sequences.
    00011 *
    00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
    00013 *
    00014 * Version 1.0.10 2011/7/15
    00015 *    Big Endian support added and Merged M0 and M3/M4 Source code.
    00016 *
    00017 * Version 1.0.3 2010/11/29
    00018 *    Re-organized the CMSIS folders and updated documentation.
    00019 *
    00020 * Version 1.0.2 2010/11/11
    00021 *    Documentation updated.
    00022 *
    00023 * Version 1.0.1 2010/10/05
    00024 *    Production release and review comments incorporated.
    00025 *
    00026 * Version 1.0.0 2010/09/20
    00027 *    Production release and review comments incorporated
    00028 *
    00029 * Version 0.0.7  2010/06/10
    00030 *    Misra-C changes done
    00031 *
    00032 * -------------------------------------------------------------------------- */
    00033
    00034 #include "arm_math.h"
    00035
    00103 void arm_conv_f32(
    00104   float32_t * pSrcA,
    00105   uint32_t srcALen,
    00106   float32_t * pSrcB,
    00107   uint32_t srcBLen,
    00108   float32_t * pDst)
    00109 {
    00110
    00111
    00112 #ifndef ARM_MATH_CM0
    00113
    00114   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00115
    00116   float32_t *pIn1;                               /* inputA pointer */
    00117   float32_t *pIn2;                               /* inputB pointer */
    00118   float32_t *pOut = pDst;                        /* output pointer */
    00119   float32_t *px;                                 /* Intermediate inputA pointer */
    00120   float32_t *py;                                 /* Intermediate inputB pointer */
    00121   float32_t *pSrc1, *pSrc2;                      /* Intermediate pointers */
    00122   float32_t sum, acc0, acc1, acc2, acc3;         /* Accumulator */
    00123   float32_t x0, x1, x2, x3, c0;                  /* Temporary variables to hold state and coefficient values */
    00124   uint32_t j, k, count, blkCnt, blockSize1, blockSize2, blockSize3;     /* loop counters */
    00125
    00126   /* The algorithm implementation is based on the lengths of the inputs. */
    00127   /* srcB is always made to slide across srcA. */
    00128   /* So srcBLen is always considered as shorter or equal to srcALen */
    00129   if(srcALen >= srcBLen)
    00130   {
    00131     /* Initialization of inputA pointer */
    00132     pIn1 = pSrcA;
    00133
    00134     /* Initialization of inputB pointer */
    00135     pIn2 = pSrcB;
    00136   }
    00137   else
    00138   {
    00139     /* Initialization of inputA pointer */
    00140     pIn1 = pSrcB;
    00141
    00142     /* Initialization of inputB pointer */
    00143     pIn2 = pSrcA;
    00144
    00145     /* srcBLen is always considered as shorter or equal to srcALen */
    00146     j = srcBLen;
    00147     srcBLen = srcALen;
    00148     srcALen = j;
    00149   }
    00150
    00151   /* conv(x,y) at n = x[n] * y[0] + x[n-1] * y[1] + x[n-2] * y[2] + ...+ x[n-N+1] * y[N -1] */
    00152   /* The function is internally
    00153    * divided into three stages according to the number of multiplications that has to be
    00154    * taken place between inputA samples and inputB samples. In the first stage of the
    00155    * algorithm, the multiplications increase by one for every iteration.
    00156    * In the second stage of the algorithm, srcBLen number of multiplications are done.
    00157    * In the third stage of the algorithm, the multiplications decrease by one
    00158    * for every iteration. */
    00159
    00160   /* The algorithm is implemented in three stages.
    00161      The loop counters of each stage is initiated here. */
    00162   blockSize1 = srcBLen - 1u;
    00163   blockSize2 = srcALen - (srcBLen - 1u);
    00164   blockSize3 = blockSize1;
    00165
    00166   /* --------------------------
    00167    * initializations of stage1
    00168    * -------------------------*/
    00169
    00170   /* sum = x[0] * y[0]
    00171    * sum = x[0] * y[1] + x[1] * y[0]
    00172    * ....
    00173    * sum = x[0] * y[srcBlen - 1] + x[1] * y[srcBlen - 2] +...+ x[srcBLen - 1] * y[0]
    00174    */
    00175
    00176   /* In this stage the MAC operations are increased by 1 for every iteration.
    00177      The count variable holds the number of MAC operations performed */
    00178   count = 1u;
    00179
    00180   /* Working pointer of inputA */
    00181   px = pIn1;
    00182
    00183   /* Working pointer of inputB */
    00184   py = pIn2;
    00185
    00186
    00187   /* ------------------------
    00188    * Stage1 process
    00189    * ----------------------*/
    00190
    00191   /* The first stage starts here */
    00192   while(blockSize1 > 0u)
    00193   {
    00194     /* Accumulator is made zero for every iteration */
    00195     sum = 0.0f;
    00196
    00197     /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00198     k = count >> 2u;
    00199
    00200     /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00201      ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00202     while(k > 0u)
    00203     {
    00204       /* x[0] * y[srcBLen - 1] */
    00205       sum += *px++ * *py--;
    00206
    00207       /* x[1] * y[srcBLen - 2] */
    00208       sum += *px++ * *py--;
    00209
    00210       /* x[2] * y[srcBLen - 3] */
    00211       sum += *px++ * *py--;
    00212
    00213       /* x[3] * y[srcBLen - 4] */
    00214       sum += *px++ * *py--;
    00215
    00216       /* Decrement the loop counter */
    00217       k--;
    00218     }
    00219
    00220     /* If the count is not a multiple of 4, compute any remaining MACs here.
    00221      ** No loop unrolling is used. */
    00222     k = count % 0x4u;
    00223
    00224     while(k > 0u)
    00225     {
    00226       /* Perform the multiply-accumulate */
    00227       sum += *px++ * *py--;
    00228
    00229       /* Decrement the loop counter */
    00230       k--;
    00231     }
    00232
    00233     /* Store the result in the accumulator in the destination buffer. */
    00234     *pOut++ = sum;
    00235
    00236     /* Update the inputA and inputB pointers for next MAC calculation */
    00237     py = pIn2 + count;
    00238     px = pIn1;
    00239
    00240     /* Increment the MAC count */
    00241     count++;
    00242
    00243     /* Decrement the loop counter */
    00244     blockSize1--;
    00245   }
    00246
    00247   /* --------------------------
    00248    * Initializations of stage2
    00249    * ------------------------*/
    00250
    00251   /* sum = x[0] * y[srcBLen-1] + x[1] * y[srcBLen-2] +...+ x[srcBLen-1] * y[0]
    00252    * sum = x[1] * y[srcBLen-1] + x[2] * y[srcBLen-2] +...+ x[srcBLen] * y[0]
    00253    * ....
    00254    * sum = x[srcALen-srcBLen-2] * y[srcBLen-1] + x[srcALen] * y[srcBLen-2] +...+ x[srcALen-1] * y[0]
    00255    */
    00256
    00257   /* Working pointer of inputA */
    00258   px = pIn1;
    00259
    00260   /* Working pointer of inputB */
    00261   pSrc2 = pIn2 + (srcBLen - 1u);
    00262   py = pSrc2;
    00263
    00264   /* count is index by which the pointer pIn1 to be incremented */
    00265   count = 1u;
    00266
    00267   /* -------------------
    00268    * Stage2 process
    00269    * ------------------*/
    00270
    00271   /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
    00272    * So, to loop unroll over blockSize2,
    00273    * srcBLen should be greater than or equal to 4 */
    00274   if(srcBLen >= 4u)
    00275   {
    00276     /* Loop unroll over blockSize2, by 4 */
    00277     blkCnt = blockSize2 >> 2u;
    00278
    00279     while(blkCnt > 0u)
    00280     {
    00281       /* Set all accumulators to zero */
    00282       acc0 = 0.0f;
    00283       acc1 = 0.0f;
    00284       acc2 = 0.0f;
    00285       acc3 = 0.0f;
    00286
    00287       /* read x[0], x[1], x[2] samples */
    00288       x0 = *(px++);
    00289       x1 = *(px++);
    00290       x2 = *(px++);
    00291
    00292       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00293       k = srcBLen >> 2u;
    00294
    00295       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00296        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00297       do
    00298       {
    00299         /* Read y[srcBLen - 1] sample */
    00300         c0 = *(py--);
    00301
    00302         /* Read x[3] sample */
    00303         x3 = *(px++);
    00304
    00305         /* Perform the multiply-accumulate */
    00306         /* acc0 +=  x[0] * y[srcBLen - 1] */
    00307         acc0 += x0 * c0;
    00308
    00309         /* acc1 +=  x[1] * y[srcBLen - 1] */
    00310         acc1 += x1 * c0;
    00311
    00312         /* acc2 +=  x[2] * y[srcBLen - 1] */
    00313         acc2 += x2 * c0;
    00314
    00315         /* acc3 +=  x[3] * y[srcBLen - 1] */
    00316         acc3 += x3 * c0;
    00317
    00318         /* Read y[srcBLen - 2] sample */
    00319         c0 = *(py--);
    00320
    00321         /* Read x[4] sample */
    00322         x0 = *(px++);
    00323
    00324         /* Perform the multiply-accumulate */
    00325         /* acc0 +=  x[1] * y[srcBLen - 2] */
    00326         acc0 += x1 * c0;
    00327         /* acc1 +=  x[2] * y[srcBLen - 2] */
    00328         acc1 += x2 * c0;
    00329         /* acc2 +=  x[3] * y[srcBLen - 2] */
    00330         acc2 += x3 * c0;
    00331         /* acc3 +=  x[4] * y[srcBLen - 2] */
    00332         acc3 += x0 * c0;
    00333
    00334         /* Read y[srcBLen - 3] sample */
    00335         c0 = *(py--);
    00336
    00337         /* Read x[5] sample */
    00338         x1 = *(px++);
    00339
    00340         /* Perform the multiply-accumulates */
    00341         /* acc0 +=  x[2] * y[srcBLen - 3] */
    00342         acc0 += x2 * c0;
    00343         /* acc1 +=  x[3] * y[srcBLen - 2] */
    00344         acc1 += x3 * c0;
    00345         /* acc2 +=  x[4] * y[srcBLen - 2] */
    00346         acc2 += x0 * c0;
    00347         /* acc3 +=  x[5] * y[srcBLen - 2] */
    00348         acc3 += x1 * c0;
    00349
    00350         /* Read y[srcBLen - 4] sample */
    00351         c0 = *(py--);
    00352
    00353         /* Read x[6] sample */
    00354         x2 = *(px++);
    00355
    00356         /* Perform the multiply-accumulates */
    00357         /* acc0 +=  x[3] * y[srcBLen - 4] */
    00358         acc0 += x3 * c0;
    00359         /* acc1 +=  x[4] * y[srcBLen - 4] */
    00360         acc1 += x0 * c0;
    00361         /* acc2 +=  x[5] * y[srcBLen - 4] */
    00362         acc2 += x1 * c0;
    00363         /* acc3 +=  x[6] * y[srcBLen - 4] */
    00364         acc3 += x2 * c0;
    00365
    00366
    00367       } while(--k);
    00368
    00369       /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00370        ** No loop unrolling is used. */
    00371       k = srcBLen % 0x4u;
    00372
    00373       while(k > 0u)
    00374       {
    00375         /* Read y[srcBLen - 5] sample */
    00376         c0 = *(py--);
    00377
    00378         /* Read x[7] sample */
    00379         x3 = *(px++);
    00380
    00381         /* Perform the multiply-accumulates */
    00382         /* acc0 +=  x[4] * y[srcBLen - 5] */
    00383         acc0 += x0 * c0;
    00384         /* acc1 +=  x[5] * y[srcBLen - 5] */
    00385         acc1 += x1 * c0;
    00386         /* acc2 +=  x[6] * y[srcBLen - 5] */
    00387         acc2 += x2 * c0;
    00388         /* acc3 +=  x[7] * y[srcBLen - 5] */
    00389         acc3 += x3 * c0;
    00390
    00391         /* Reuse the present samples for the next MAC */
    00392         x0 = x1;
    00393         x1 = x2;
    00394         x2 = x3;
    00395
    00396         /* Decrement the loop counter */
    00397         k--;
    00398       }
    00399
    00400       /* Store the result in the accumulator in the destination buffer. */
    00401       *pOut++ = acc0;
    00402       *pOut++ = acc1;
    00403       *pOut++ = acc2;
    00404       *pOut++ = acc3;
    00405
    00406       /* Update the inputA and inputB pointers for next MAC calculation */
    00407       px = pIn1 + (count * 4u);
    00408       py = pSrc2;
    00409
    00410       /* Increment the pointer pIn1 index, count by 1 */
    00411       count++;
    00412
    00413       /* Decrement the loop counter */
    00414       blkCnt--;
    00415     }
    00416
    00417     /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
    00418      ** No loop unrolling is used. */
    00419     blkCnt = blockSize2 % 0x4u;
    00420
    00421     while(blkCnt > 0u)
    00422     {
    00423       /* Accumulator is made zero for every iteration */
    00424       sum = 0.0f;
    00425
    00426       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00427       k = srcBLen >> 2u;
    00428
    00429       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00430        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00431       while(k > 0u)
    00432       {
    00433         /* Perform the multiply-accumulates */
    00434         sum += *px++ * *py--;
    00435         sum += *px++ * *py--;
    00436         sum += *px++ * *py--;
    00437         sum += *px++ * *py--;
    00438
    00439         /* Decrement the loop counter */
    00440         k--;
    00441       }
    00442
    00443       /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00444        ** No loop unrolling is used. */
    00445       k = srcBLen % 0x4u;
    00446
    00447       while(k > 0u)
    00448       {
    00449         /* Perform the multiply-accumulate */
    00450         sum += *px++ * *py--;
    00451
    00452         /* Decrement the loop counter */
    00453         k--;
    00454       }
    00455
    00456       /* Store the result in the accumulator in the destination buffer. */
    00457       *pOut++ = sum;
    00458
    00459       /* Update the inputA and inputB pointers for next MAC calculation */
    00460       px = pIn1 + count;
    00461       py = pSrc2;
    00462
    00463       /* Increment the MAC count */
    00464       count++;
    00465
    00466       /* Decrement the loop counter */
    00467       blkCnt--;
    00468     }
    00469   }
    00470   else
    00471   {
    00472     /* If the srcBLen is not a multiple of 4,
    00473      * the blockSize2 loop cannot be unrolled by 4 */
    00474     blkCnt = blockSize2;
    00475
    00476     while(blkCnt > 0u)
    00477     {
    00478       /* Accumulator is made zero for every iteration */
    00479       sum = 0.0f;
    00480
    00481       /* srcBLen number of MACS should be performed */
    00482       k = srcBLen;
    00483
    00484       while(k > 0u)
    00485       {
    00486         /* Perform the multiply-accumulate */
    00487         sum += *px++ * *py--;
    00488
    00489         /* Decrement the loop counter */
    00490         k--;
    00491       }
    00492
    00493       /* Store the result in the accumulator in the destination buffer. */
    00494       *pOut++ = sum;
    00495
    00496       /* Update the inputA and inputB pointers for next MAC calculation */
    00497       px = pIn1 + count;
    00498       py = pSrc2;
    00499
    00500       /* Increment the MAC count */
    00501       count++;
    00502
    00503       /* Decrement the loop counter */
    00504       blkCnt--;
    00505     }
    00506   }
    00507
    00508
    00509   /* --------------------------
    00510    * Initializations of stage3
    00511    * -------------------------*/
    00512
    00513   /* sum += x[srcALen-srcBLen+1] * y[srcBLen-1] + x[srcALen-srcBLen+2] * y[srcBLen-2] +...+ x[srcALen-1] * y[1]
    00514    * sum += x[srcALen-srcBLen+2] * y[srcBLen-1] + x[srcALen-srcBLen+3] * y[srcBLen-2] +...+ x[srcALen-1] * y[2]
    00515    * ....
    00516    * sum +=  x[srcALen-2] * y[srcBLen-1] + x[srcALen-1] * y[srcBLen-2]
    00517    * sum +=  x[srcALen-1] * y[srcBLen-1]
    00518    */
    00519
    00520   /* In this stage the MAC operations are decreased by 1 for every iteration.
    00521      The blockSize3 variable holds the number of MAC operations performed */
    00522
    00523   /* Working pointer of inputA */
    00524   pSrc1 = (pIn1 + srcALen) - (srcBLen - 1u);
    00525   px = pSrc1;
    00526
    00527   /* Working pointer of inputB */
    00528   pSrc2 = pIn2 + (srcBLen - 1u);
    00529   py = pSrc2;
    00530
    00531   /* -------------------
    00532    * Stage3 process
    00533    * ------------------*/
    00534
    00535   while(blockSize3 > 0u)
    00536   {
    00537     /* Accumulator is made zero for every iteration */
    00538     sum = 0.0f;
    00539
    00540     /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00541     k = blockSize3 >> 2u;
    00542
    00543     /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00544      ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00545     while(k > 0u)
    00546     {
    00547       /* sum += x[srcALen - srcBLen + 1] * y[srcBLen - 1] */
    00548       sum += *px++ * *py--;
    00549
    00550       /* sum += x[srcALen - srcBLen + 2] * y[srcBLen - 2] */
    00551       sum += *px++ * *py--;
    00552
    00553       /* sum += x[srcALen - srcBLen + 3] * y[srcBLen - 3] */
    00554       sum += *px++ * *py--;
    00555
    00556       /* sum += x[srcALen - srcBLen + 4] * y[srcBLen - 4] */
    00557       sum += *px++ * *py--;
    00558
    00559       /* Decrement the loop counter */
    00560       k--;
    00561     }
    00562
    00563     /* If the blockSize3 is not a multiple of 4, compute any remaining MACs here.
    00564      ** No loop unrolling is used. */
    00565     k = blockSize3 % 0x4u;
    00566
    00567     while(k > 0u)
    00568     {
    00569       /* Perform the multiply-accumulates */
    00570       /* sum +=  x[srcALen-1] * y[srcBLen-1] */
    00571       sum += *px++ * *py--;
    00572
    00573       /* Decrement the loop counter */
    00574       k--;
    00575     }
    00576
    00577     /* Store the result in the accumulator in the destination buffer. */
    00578     *pOut++ = sum;
    00579
    00580     /* Update the inputA and inputB pointers for next MAC calculation */
    00581     px = ++pSrc1;
    00582     py = pSrc2;
    00583
    00584     /* Decrement the loop counter */
    00585     blockSize3--;
    00586   }
    00587
    00588 #else
    00589
    00590   /* Run the below code for Cortex-M0 */
    00591
    00592   float32_t *pIn1 = pSrcA;                       /* inputA pointer */
    00593   float32_t *pIn2 = pSrcB;                       /* inputB pointer */
    00594   float32_t sum;                                 /* Accumulator */
    00595   uint32_t i, j;                                 /* loop counters */
    00596
    00597   /* Loop to calculate convolution for output length number of times */
    00598   for (i = 0u; i < ((srcALen + srcBLen) - 1u); i++)
    00599   {
    00600     /* Initialize sum with zero to carry out MAC operations */
    00601     sum = 0.0f;
    00602
    00603     /* Loop to perform MAC operations according to convolution equation */
    00604     for (j = 0u; j <= i; j++)
    00605     {
    00606       /* Check the array limitations */
    00607       if((((i - j) < srcBLen) && (j < srcALen)))
    00608       {
    00609         /* z[i] += x[i-j] * y[j] */
    00610         sum += pIn1[j] * pIn2[i - j];
    00611       }
    00612     }
    00613     /* Store the output in the destination buffer */
    00614     pDst[i] = sum;
    00615   }
    00616
    00617 #endif /*   #ifndef ARM_MATH_CM0        */
    00618
    00619 }
    00620

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