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# arm_correlate_q31.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_correlate_q31.c
    00009 *
    00010 * Description:  Correlation of Q31 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
    00071 void arm_correlate_q31(
    00072   q31_t * pSrcA,
    00073   uint32_t srcALen,
    00074   q31_t * pSrcB,
    00075   uint32_t srcBLen,
    00076   q31_t * pDst)
    00077 {
    00078
    00079 #ifndef ARM_MATH_CM0
    00080
    00081   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00082
    00083   q31_t *pIn1;                                   /* inputA pointer               */
    00084   q31_t *pIn2;                                   /* inputB pointer               */
    00085   q31_t *pOut = pDst;                            /* output pointer               */
    00086   q31_t *px;                                     /* Intermediate inputA pointer  */
    00087   q31_t *py;                                     /* Intermediate inputB pointer  */
    00088   q31_t *pSrc1;                                  /* Intermediate pointers        */
    00089   q63_t sum, acc0, acc1, acc2, acc3;             /* Accumulators                  */
    00090   q31_t x0, x1, x2, x3, c0;                      /* temporary variables for holding input and coefficient values */
    00091   uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3;  /* loop counter                 */
    00092   int32_t inc = 1;                               /* Destination address modifier */
    00093
    00094
    00095   /* The algorithm implementation is based on the lengths of the inputs. */
    00096   /* srcB is always made to slide across srcA. */
    00097   /* So srcBLen is always considered as shorter or equal to srcALen */
    00098   /* But CORR(x, y) is reverse of CORR(y, x) */
    00099   /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
    00100   /* and the destination pointer modifier, inc is set to -1 */
    00101   /* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */
    00102   /* But to improve the performance,
    00103    * we include zeroes in the output instead of zero padding either of the the inputs*/
    00104   /* If srcALen > srcBLen,
    00105    * (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */
    00106   /* If srcALen < srcBLen,
    00107    * (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */
    00108   if(srcALen >= srcBLen)
    00109   {
    00110     /* Initialization of inputA pointer */
    00111     pIn1 = (pSrcA);
    00112
    00113     /* Initialization of inputB pointer */
    00114     pIn2 = (pSrcB);
    00115
    00116     /* Number of output samples is calculated */
    00117     outBlockSize = (2u * srcALen) - 1u;
    00118
    00119     /* When srcALen > srcBLen, zero padding is done to srcB
    00120      * to make their lengths equal.
    00121      * Instead, (outBlockSize - (srcALen + srcBLen - 1))
    00122      * number of output samples are made zero */
    00123     j = outBlockSize - (srcALen + (srcBLen - 1u));
    00124
    00125     /* Updating the pointer position to non zero value */
    00126     pOut += j;
    00127
    00128   }
    00129   else
    00130   {
    00131     /* Initialization of inputA pointer */
    00132     pIn1 = (pSrcB);
    00133
    00134     /* Initialization of inputB pointer */
    00135     pIn2 = (pSrcA);
    00136
    00137     /* srcBLen is always considered as shorter or equal to srcALen */
    00138     j = srcBLen;
    00139     srcBLen = srcALen;
    00140     srcALen = j;
    00141
    00142     /* CORR(x, y) = Reverse order(CORR(y, x)) */
    00143     /* Hence set the destination pointer to point to the last output sample */
    00144     pOut = pDst + ((srcALen + srcBLen) - 2u);
    00145
    00146     /* Destination address modifier is set to -1 */
    00147     inc = -1;
    00148
    00149   }
    00150
    00151   /* The function is internally
    00152    * divided into three parts according to the number of multiplications that has to be
    00153    * taken place between inputA samples and inputB samples. In the first part of the
    00154    * algorithm, the multiplications increase by one for every iteration.
    00155    * In the second part of the algorithm, srcBLen number of multiplications are done.
    00156    * In the third part of the algorithm, the multiplications decrease by one
    00157    * for every iteration.*/
    00158   /* The algorithm is implemented in three stages.
    00159    * The loop counters of each stage is initiated here. */
    00160   blockSize1 = srcBLen - 1u;
    00161   blockSize2 = srcALen - (srcBLen - 1u);
    00162   blockSize3 = blockSize1;
    00163
    00164   /* --------------------------
    00165    * Initializations of stage1
    00166    * -------------------------*/
    00167
    00168   /* sum = x[0] * y[srcBlen - 1]
    00169    * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1]
    00170    * ....
    00171    * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1]
    00172    */
    00173
    00174   /* In this stage the MAC operations are increased by 1 for every iteration.
    00175      The count variable holds the number of MAC operations performed */
    00176   count = 1u;
    00177
    00178   /* Working pointer of inputA */
    00179   px = pIn1;
    00180
    00181   /* Working pointer of inputB */
    00182   pSrc1 = pIn2 + (srcBLen - 1u);
    00183   py = pSrc1;
    00184
    00185   /* ------------------------
    00186    * Stage1 process
    00187    * ----------------------*/
    00188
    00189   /* The first stage starts here */
    00190   while(blockSize1 > 0u)
    00191   {
    00192     /* Accumulator is made zero for every iteration */
    00193     sum = 0;
    00194
    00195     /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00196     k = count >> 2;
    00197
    00198     /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00199      ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00200     while(k > 0u)
    00201     {
    00202       /* x[0] * y[srcBLen - 4] */
    00203       sum += (q63_t) * px++ * (*py++);
    00204       /* x[1] * y[srcBLen - 3] */
    00205       sum += (q63_t) * px++ * (*py++);
    00206       /* x[2] * y[srcBLen - 2] */
    00207       sum += (q63_t) * px++ * (*py++);
    00208       /* x[3] * y[srcBLen - 1] */
    00209       sum += (q63_t) * px++ * (*py++);
    00210
    00211       /* Decrement the loop counter */
    00212       k--;
    00213     }
    00214
    00215     /* If the count is not a multiple of 4, compute any remaining MACs here.
    00216      ** No loop unrolling is used. */
    00217     k = count % 0x4u;
    00218
    00219     while(k > 0u)
    00220     {
    00221       /* Perform the multiply-accumulates */
    00222       /* x[0] * y[srcBLen - 1] */
    00223       sum += (q63_t) * px++ * (*py++);
    00224
    00225       /* Decrement the loop counter */
    00226       k--;
    00227     }
    00228
    00229     /* Store the result in the accumulator in the destination buffer. */
    00230     *pOut = (q31_t) (sum >> 31);
    00231     /* Destination pointer is updated according to the address modifier, inc */
    00232     pOut += inc;
    00233
    00234     /* Update the inputA and inputB pointers for next MAC calculation */
    00235     py = pSrc1 - count;
    00236     px = pIn1;
    00237
    00238     /* Increment the MAC count */
    00239     count++;
    00240
    00241     /* Decrement the loop counter */
    00242     blockSize1--;
    00243   }
    00244
    00245   /* --------------------------
    00246    * Initializations of stage2
    00247    * ------------------------*/
    00248
    00249   /* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1]
    00250    * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1]
    00251    * ....
    00252    * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
    00253    */
    00254
    00255   /* Working pointer of inputA */
    00256   px = pIn1;
    00257
    00258   /* Working pointer of inputB */
    00259   py = pIn2;
    00260
    00261   /* count is index by which the pointer pIn1 to be incremented */
    00262   count = 1u;
    00263
    00264   /* -------------------
    00265    * Stage2 process
    00266    * ------------------*/
    00267
    00268   /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
    00269    * So, to loop unroll over blockSize2,
    00270    * srcBLen should be greater than or equal to 4 */
    00271   if(srcBLen >= 4u)
    00272   {
    00273     /* Loop unroll over blockSize2, by 4 */
    00274     blkCnt = blockSize2 >> 2u;
    00275
    00276     while(blkCnt > 0u)
    00277     {
    00278       /* Set all accumulators to zero */
    00279       acc0 = 0;
    00280       acc1 = 0;
    00281       acc2 = 0;
    00282       acc3 = 0;
    00283
    00284       /* read x[0], x[1], x[2] samples */
    00285       x0 = *(px++);
    00286       x1 = *(px++);
    00287       x2 = *(px++);
    00288
    00289       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00290       k = srcBLen >> 2u;
    00291
    00292       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00293        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00294       do
    00295       {
    00296         /* Read y[0] sample */
    00297         c0 = *(py++);
    00298
    00299         /* Read x[3] sample */
    00300         x3 = *(px++);
    00301
    00302         /* Perform the multiply-accumulate */
    00303         /* acc0 +=  x[0] * y[0] */
    00304         acc0 += ((q63_t) x0 * c0);
    00305         /* acc1 +=  x[1] * y[0] */
    00306         acc1 += ((q63_t) x1 * c0);
    00307         /* acc2 +=  x[2] * y[0] */
    00308         acc2 += ((q63_t) x2 * c0);
    00309         /* acc3 +=  x[3] * y[0] */
    00310         acc3 += ((q63_t) x3 * c0);
    00311
    00312         /* Read y[1] sample */
    00313         c0 = *(py++);
    00314
    00315         /* Read x[4] sample */
    00316         x0 = *(px++);
    00317
    00318         /* Perform the multiply-accumulates */
    00319         /* acc0 +=  x[1] * y[1] */
    00320         acc0 += ((q63_t) x1 * c0);
    00321         /* acc1 +=  x[2] * y[1] */
    00322         acc1 += ((q63_t) x2 * c0);
    00323         /* acc2 +=  x[3] * y[1] */
    00324         acc2 += ((q63_t) x3 * c0);
    00325         /* acc3 +=  x[4] * y[1] */
    00326         acc3 += ((q63_t) x0 * c0);
    00327         /* Read y[2] sample */
    00328         c0 = *(py++);
    00329
    00330         /* Read x[5] sample */
    00331         x1 = *(px++);
    00332
    00333         /* Perform the multiply-accumulates */
    00334         /* acc0 +=  x[2] * y[2] */
    00335         acc0 += ((q63_t) x2 * c0);
    00336         /* acc1 +=  x[3] * y[2] */
    00337         acc1 += ((q63_t) x3 * c0);
    00338         /* acc2 +=  x[4] * y[2] */
    00339         acc2 += ((q63_t) x0 * c0);
    00340         /* acc3 +=  x[5] * y[2] */
    00341         acc3 += ((q63_t) x1 * c0);
    00342
    00343         /* Read y[3] sample */
    00344         c0 = *(py++);
    00345
    00346         /* Read x[6] sample */
    00347         x2 = *(px++);
    00348
    00349         /* Perform the multiply-accumulates */
    00350         /* acc0 +=  x[3] * y[3] */
    00351         acc0 += ((q63_t) x3 * c0);
    00352         /* acc1 +=  x[4] * y[3] */
    00353         acc1 += ((q63_t) x0 * c0);
    00354         /* acc2 +=  x[5] * y[3] */
    00355         acc2 += ((q63_t) x1 * c0);
    00356         /* acc3 +=  x[6] * y[3] */
    00357         acc3 += ((q63_t) x2 * c0);
    00358
    00359
    00360       } while(--k);
    00361
    00362       /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00363        ** No loop unrolling is used. */
    00364       k = srcBLen % 0x4u;
    00365
    00366       while(k > 0u)
    00367       {
    00368         /* Read y[4] sample */
    00369         c0 = *(py++);
    00370
    00371         /* Read x[7] sample */
    00372         x3 = *(px++);
    00373
    00374         /* Perform the multiply-accumulates */
    00375         /* acc0 +=  x[4] * y[4] */
    00376         acc0 += ((q63_t) x0 * c0);
    00377         /* acc1 +=  x[5] * y[4] */
    00378         acc1 += ((q63_t) x1 * c0);
    00379         /* acc2 +=  x[6] * y[4] */
    00380         acc2 += ((q63_t) x2 * c0);
    00381         /* acc3 +=  x[7] * y[4] */
    00382         acc3 += ((q63_t) x3 * c0);
    00383
    00384         /* Reuse the present samples for the next MAC */
    00385         x0 = x1;
    00386         x1 = x2;
    00387         x2 = x3;
    00388
    00389         /* Decrement the loop counter */
    00390         k--;
    00391       }
    00392
    00393       /* Store the result in the accumulator in the destination buffer. */
    00394       *pOut = (q31_t) (acc0 >> 31);
    00395       /* Destination pointer is updated according to the address modifier, inc */
    00396       pOut += inc;
    00397
    00398       *pOut = (q31_t) (acc1 >> 31);
    00399       pOut += inc;
    00400
    00401       *pOut = (q31_t) (acc2 >> 31);
    00402       pOut += inc;
    00403
    00404       *pOut = (q31_t) (acc3 >> 31);
    00405       pOut += inc;
    00406
    00407       /* Update the inputA and inputB pointers for next MAC calculation */
    00408       px = pIn1 + (count * 4u);
    00409       py = pIn2;
    00410
    00411       /* Increment the pointer pIn1 index, count by 1 */
    00412       count++;
    00413
    00414       /* Decrement the loop counter */
    00415       blkCnt--;
    00416     }
    00417
    00418     /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
    00419      ** No loop unrolling is used. */
    00420     blkCnt = blockSize2 % 0x4u;
    00421
    00422     while(blkCnt > 0u)
    00423     {
    00424       /* Accumulator is made zero for every iteration */
    00425       sum = 0;
    00426
    00427       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00428       k = srcBLen >> 2u;
    00429
    00430       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00431        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00432       while(k > 0u)
    00433       {
    00434         /* Perform the multiply-accumulates */
    00435         sum += (q63_t) * px++ * (*py++);
    00436         sum += (q63_t) * px++ * (*py++);
    00437         sum += (q63_t) * px++ * (*py++);
    00438         sum += (q63_t) * px++ * (*py++);
    00439
    00440         /* Decrement the loop counter */
    00441         k--;
    00442       }
    00443
    00444       /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00445        ** No loop unrolling is used. */
    00446       k = srcBLen % 0x4u;
    00447
    00448       while(k > 0u)
    00449       {
    00450         /* Perform the multiply-accumulate */
    00451         sum += (q63_t) * px++ * (*py++);
    00452
    00453         /* Decrement the loop counter */
    00454         k--;
    00455       }
    00456
    00457       /* Store the result in the accumulator in the destination buffer. */
    00458       *pOut = (q31_t) (sum >> 31);
    00459       /* Destination pointer is updated according to the address modifier, inc */
    00460       pOut += inc;
    00461
    00462       /* Update the inputA and inputB pointers for next MAC calculation */
    00463       px = pIn1 + count;
    00464       py = pIn2;
    00465
    00466       /* Increment the MAC count */
    00467       count++;
    00468
    00469       /* Decrement the loop counter */
    00470       blkCnt--;
    00471     }
    00472   }
    00473   else
    00474   {
    00475     /* If the srcBLen is not a multiple of 4,
    00476      * the blockSize2 loop cannot be unrolled by 4 */
    00477     blkCnt = blockSize2;
    00478
    00479     while(blkCnt > 0u)
    00480     {
    00481       /* Accumulator is made zero for every iteration */
    00482       sum = 0;
    00483
    00484       /* Loop over srcBLen */
    00485       k = srcBLen;
    00486
    00487       while(k > 0u)
    00488       {
    00489         /* Perform the multiply-accumulate */
    00490         sum += (q63_t) * px++ * (*py++);
    00491
    00492         /* Decrement the loop counter */
    00493         k--;
    00494       }
    00495
    00496       /* Store the result in the accumulator in the destination buffer. */
    00497       *pOut = (q31_t) (sum >> 31);
    00498       /* Destination pointer is updated according to the address modifier, inc */
    00499       pOut += inc;
    00500
    00501       /* Update the inputA and inputB pointers for next MAC calculation */
    00502       px = pIn1 + count;
    00503       py = pIn2;
    00504
    00505       /* Increment the MAC count */
    00506       count++;
    00507
    00508       /* Decrement the loop counter */
    00509       blkCnt--;
    00510     }
    00511   }
    00512
    00513   /* --------------------------
    00514    * Initializations of stage3
    00515    * -------------------------*/
    00516
    00517   /* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
    00518    * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
    00519    * ....
    00520    * sum +=  x[srcALen-2] * y[0] + x[srcALen-1] * y[1]
    00521    * sum +=  x[srcALen-1] * y[0]
    00522    */
    00523
    00524   /* In this stage the MAC operations are decreased by 1 for every iteration.
    00525      The count variable holds the number of MAC operations performed */
    00526   count = srcBLen - 1u;
    00527
    00528   /* Working pointer of inputA */
    00529   pSrc1 = pIn1 + (srcALen - (srcBLen - 1u));
    00530   px = pSrc1;
    00531
    00532   /* Working pointer of inputB */
    00533   py = pIn2;
    00534
    00535   /* -------------------
    00536    * Stage3 process
    00537    * ------------------*/
    00538
    00539   while(blockSize3 > 0u)
    00540   {
    00541     /* Accumulator is made zero for every iteration */
    00542     sum = 0;
    00543
    00544     /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00545     k = count >> 2u;
    00546
    00547     /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00548      ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00549     while(k > 0u)
    00550     {
    00551       /* Perform the multiply-accumulates */
    00552       /* sum += x[srcALen - srcBLen + 4] * y[3] */
    00553       sum += (q63_t) * px++ * (*py++);
    00554       /* sum += x[srcALen - srcBLen + 3] * y[2] */
    00555       sum += (q63_t) * px++ * (*py++);
    00556       /* sum += x[srcALen - srcBLen + 2] * y[1] */
    00557       sum += (q63_t) * px++ * (*py++);
    00558       /* sum += x[srcALen - srcBLen + 1] * y[0] */
    00559       sum += (q63_t) * px++ * (*py++);
    00560
    00561       /* Decrement the loop counter */
    00562       k--;
    00563     }
    00564
    00565     /* If the count is not a multiple of 4, compute any remaining MACs here.
    00566      ** No loop unrolling is used. */
    00567     k = count % 0x4u;
    00568
    00569     while(k > 0u)
    00570     {
    00571       /* Perform the multiply-accumulates */
    00572       sum += (q63_t) * px++ * (*py++);
    00573
    00574       /* Decrement the loop counter */
    00575       k--;
    00576     }
    00577
    00578     /* Store the result in the accumulator in the destination buffer. */
    00579     *pOut = (q31_t) (sum >> 31);
    00580     /* Destination pointer is updated according to the address modifier, inc */
    00581     pOut += inc;
    00582
    00583     /* Update the inputA and inputB pointers for next MAC calculation */
    00584     px = ++pSrc1;
    00585     py = pIn2;
    00586
    00587     /* Decrement the MAC count */
    00588     count--;
    00589
    00590     /* Decrement the loop counter */
    00591     blockSize3--;
    00592   }
    00593
    00594 #else
    00595
    00596   /* Run the below code for Cortex-M0 */
    00597
    00598   q31_t *pIn1 = pSrcA;                           /* inputA pointer               */
    00599   q31_t *pIn2 = pSrcB + (srcBLen - 1u);          /* inputB pointer               */
    00600   q63_t sum;                                     /* Accumulators                  */
    00601   uint32_t i = 0u, j;                            /* loop counters */
    00602   uint32_t inv = 0u;                             /* Reverse order flag */
    00603   uint32_t tot = 0u;                             /* Length */
    00604
    00605   /* The algorithm implementation is based on the lengths of the inputs. */
    00606   /* srcB is always made to slide across srcA. */
    00607   /* So srcBLen is always considered as shorter or equal to srcALen */
    00608   /* But CORR(x, y) is reverse of CORR(y, x) */
    00609   /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
    00610   /* and a varaible, inv is set to 1 */
    00611   /* If lengths are not equal then zero pad has to be done to  make the two
    00612    * inputs of same length. But to improve the performance, we include zeroes
    00613    * in the output instead of zero padding either of the the inputs*/
    00614   /* If srcALen > srcBLen, (srcALen - srcBLen) zeroes has to included in the
    00615    * starting of the output buffer */
    00616   /* If srcALen < srcBLen, (srcALen - srcBLen) zeroes has to included in the
    00617    * ending of the output buffer */
    00618   /* Once the zero padding is done the remaining of the output is calcualted
    00619    * using convolution but with the shorter signal time shifted. */
    00620
    00621   /* Calculate the length of the remaining sequence */
    00622   tot = ((srcALen + srcBLen) - 2u);
    00623
    00624   if(srcALen > srcBLen)
    00625   {
    00626     /* Calculating the number of zeros to be padded to the output */
    00627     j = srcALen - srcBLen;
    00628
    00629     /* Initialise the pointer after zero padding */
    00630     pDst += j;
    00631   }
    00632
    00633   else if(srcALen < srcBLen)
    00634   {
    00635     /* Initialization to inputB pointer */
    00636     pIn1 = pSrcB;
    00637
    00638     /* Initialization to the end of inputA pointer */
    00639     pIn2 = pSrcA + (srcALen - 1u);
    00640
    00641     /* Initialisation of the pointer after zero padding */
    00642     pDst = pDst + tot;
    00643
    00644     /* Swapping the lengths */
    00645     j = srcALen;
    00646     srcALen = srcBLen;
    00647     srcBLen = j;
    00648
    00649     /* Setting the reverse flag */
    00650     inv = 1;
    00651
    00652   }
    00653
    00654   /* Loop to calculate convolution for output length number of times */
    00655   for (i = 0u; i <= tot; i++)
    00656   {
    00657     /* Initialize sum with zero to carry on MAC operations */
    00658     sum = 0;
    00659
    00660     /* Loop to perform MAC operations according to convolution equation */
    00661     for (j = 0u; j <= i; j++)
    00662     {
    00663       /* Check the array limitations */
    00664       if((((i - j) < srcBLen) && (j < srcALen)))
    00665       {
    00666         /* z[i] += x[i-j] * y[j] */
    00667         sum += ((q63_t) pIn1[j] * pIn2[-((int32_t) i - j)]);
    00668       }
    00669     }
    00670     /* Store the output in the destination buffer */
    00671     if(inv == 1)
    00672       *pDst-- = (q31_t) (sum >> 31u);
    00673     else
    00674       *pDst++ = (q31_t) (sum >> 31u);
    00675   }
    00676
    00677 #endif /*   #ifndef ARM_MATH_CM0 */
    00678
    00679 }
    00680

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