CMSIS DSP Software Library: arm_correlate_q7.c Source File

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# arm_correlate_q7.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_q7.c
    00009 *
    00010 * Description:  Correlation of Q7 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
    00065 void arm_correlate_q7(
    00066   q7_t * pSrcA,
    00067   uint32_t srcALen,
    00068   q7_t * pSrcB,
    00069   uint32_t srcBLen,
    00070   q7_t * pDst)
    00071 {
    00072
    00073
    00074 #ifndef ARM_MATH_CM0
    00075
    00076   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00077
    00078   q7_t *pIn1;                                    /* inputA pointer               */
    00079   q7_t *pIn2;                                    /* inputB pointer               */
    00080   q7_t *pOut = pDst;                             /* output pointer               */
    00081   q7_t *px;                                      /* Intermediate inputA pointer  */
    00082   q7_t *py;                                      /* Intermediate inputB pointer  */
    00083   q7_t *pSrc1;                                   /* Intermediate pointers        */
    00084   q31_t sum, acc0, acc1, acc2, acc3;             /* Accumulators                  */
    00085   q31_t input1, input2;                          /* temporary variables */
    00086   q15_t in1, in2;                                /* temporary variables */
    00087   q7_t x0, x1, x2, x3, c0, c1;                   /* temporary variables for holding input and coefficient values */
    00088   uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3;  /* loop counter                 */
    00089   int32_t inc = 1;
    00090
    00091
    00092   /* The algorithm implementation is based on the lengths of the inputs. */
    00093   /* srcB is always made to slide across srcA. */
    00094   /* So srcBLen is always considered as shorter or equal to srcALen */
    00095   /* But CORR(x, y) is reverse of CORR(y, x) */
    00096   /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
    00097   /* and the destination pointer modifier, inc is set to -1 */
    00098   /* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */
    00099   /* But to improve the performance,
    00100    * we include zeroes in the output instead of zero padding either of the the inputs*/
    00101   /* If srcALen > srcBLen,
    00102    * (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */
    00103   /* If srcALen < srcBLen,
    00104    * (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */
    00105   if(srcALen >= srcBLen)
    00106   {
    00107     /* Initialization of inputA pointer */
    00108     pIn1 = (pSrcA);
    00109
    00110     /* Initialization of inputB pointer */
    00111     pIn2 = (pSrcB);
    00112
    00113     /* Number of output samples is calculated */
    00114     outBlockSize = (2u * srcALen) - 1u;
    00115
    00116     /* When srcALen > srcBLen, zero padding is done to srcB
    00117      * to make their lengths equal.
    00118      * Instead, (outBlockSize - (srcALen + srcBLen - 1))
    00119      * number of output samples are made zero */
    00120     j = outBlockSize - (srcALen + (srcBLen - 1u));
    00121
    00122     /* Updating the pointer position to non zero value */
    00123     pOut += j;
    00124
    00125   }
    00126   else
    00127   {
    00128     /* Initialization of inputA pointer */
    00129     pIn1 = (pSrcB);
    00130
    00131     /* Initialization of inputB pointer */
    00132     pIn2 = (pSrcA);
    00133
    00134     /* srcBLen is always considered as shorter or equal to srcALen */
    00135     j = srcBLen;
    00136     srcBLen = srcALen;
    00137     srcALen = j;
    00138
    00139     /* CORR(x, y) = Reverse order(CORR(y, x)) */
    00140     /* Hence set the destination pointer to point to the last output sample */
    00141     pOut = pDst + ((srcALen + srcBLen) - 2u);
    00142
    00143     /* Destination address modifier is set to -1 */
    00144     inc = -1;
    00145
    00146   }
    00147
    00148   /* The function is internally
    00149    * divided into three parts according to the number of multiplications that has to be
    00150    * taken place between inputA samples and inputB samples. In the first part of the
    00151    * algorithm, the multiplications increase by one for every iteration.
    00152    * In the second part of the algorithm, srcBLen number of multiplications are done.
    00153    * In the third part of the algorithm, the multiplications decrease by one
    00154    * for every iteration.*/
    00155   /* The algorithm is implemented in three stages.
    00156    * The loop counters of each stage is initiated here. */
    00157   blockSize1 = srcBLen - 1u;
    00158   blockSize2 = srcALen - (srcBLen - 1u);
    00159   blockSize3 = blockSize1;
    00160
    00161   /* --------------------------
    00162    * Initializations of stage1
    00163    * -------------------------*/
    00164
    00165   /* sum = x[0] * y[srcBlen - 1]
    00166    * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1]
    00167    * ....
    00168    * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1]
    00169    */
    00170
    00171   /* In this stage the MAC operations are increased by 1 for every iteration.
    00172      The count variable holds the number of MAC operations performed */
    00173   count = 1u;
    00174
    00175   /* Working pointer of inputA */
    00176   px = pIn1;
    00177
    00178   /* Working pointer of inputB */
    00179   pSrc1 = pIn2 + (srcBLen - 1u);
    00180   py = pSrc1;
    00181
    00182   /* ------------------------
    00183    * Stage1 process
    00184    * ----------------------*/
    00185
    00186   /* The first stage starts here */
    00187   while(blockSize1 > 0u)
    00188   {
    00189     /* Accumulator is made zero for every iteration */
    00190     sum = 0;
    00191
    00192     /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00193     k = count >> 2;
    00194
    00195     /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00196      ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00197     while(k > 0u)
    00198     {
    00199       /* x[0] , x[1] */
    00200       in1 = (q15_t) * px++;
    00201       in2 = (q15_t) * px++;
    00202       input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00203
    00204       /* y[srcBLen - 4] , y[srcBLen - 3] */
    00205       in1 = (q15_t) * py++;
    00206       in2 = (q15_t) * py++;
    00207       input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00208
    00209       /* x[0] * y[srcBLen - 4] */
    00210       /* x[1] * y[srcBLen - 3] */
    00211       sum = __SMLAD(input1, input2, sum);
    00212
    00213       /* x[2] , x[3] */
    00214       in1 = (q15_t) * px++;
    00215       in2 = (q15_t) * px++;
    00216       input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00217
    00218       /* y[srcBLen - 2] , y[srcBLen - 1] */
    00219       in1 = (q15_t) * py++;
    00220       in2 = (q15_t) * py++;
    00221       input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00222
    00223       /* x[2] * y[srcBLen - 2] */
    00224       /* x[3] * y[srcBLen - 1] */
    00225       sum = __SMLAD(input1, input2, sum);
    00226
    00227
    00228       /* Decrement the loop counter */
    00229       k--;
    00230     }
    00231
    00232     /* If the count is not a multiple of 4, compute any remaining MACs here.
    00233      ** No loop unrolling is used. */
    00234     k = count % 0x4u;
    00235
    00236     while(k > 0u)
    00237     {
    00238       /* Perform the multiply-accumulates */
    00239       /* x[0] * y[srcBLen - 1] */
    00240       sum += (q31_t) ((q15_t) * px++ * *py++);
    00241
    00242       /* Decrement the loop counter */
    00243       k--;
    00244     }
    00245
    00246     /* Store the result in the accumulator in the destination buffer. */
    00247     *pOut = (q7_t) (__SSAT(sum >> 7, 8));
    00248     /* Destination pointer is updated according to the address modifier, inc */
    00249     pOut += inc;
    00250
    00251     /* Update the inputA and inputB pointers for next MAC calculation */
    00252     py = pSrc1 - count;
    00253     px = pIn1;
    00254
    00255     /* Increment the MAC count */
    00256     count++;
    00257
    00258     /* Decrement the loop counter */
    00259     blockSize1--;
    00260   }
    00261
    00262   /* --------------------------
    00263    * Initializations of stage2
    00264    * ------------------------*/
    00265
    00266   /* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1]
    00267    * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1]
    00268    * ....
    00269    * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
    00270    */
    00271
    00272   /* Working pointer of inputA */
    00273   px = pIn1;
    00274
    00275   /* Working pointer of inputB */
    00276   py = pIn2;
    00277
    00278   /* count is index by which the pointer pIn1 to be incremented */
    00279   count = 1u;
    00280
    00281   /* -------------------
    00282    * Stage2 process
    00283    * ------------------*/
    00284
    00285   /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
    00286    * So, to loop unroll over blockSize2,
    00287    * srcBLen should be greater than or equal to 4 */
    00288   if(srcBLen >= 4u)
    00289   {
    00290     /* Loop unroll over blockSize2, by 4 */
    00291     blkCnt = blockSize2 >> 2u;
    00292
    00293     while(blkCnt > 0u)
    00294     {
    00295       /* Set all accumulators to zero */
    00296       acc0 = 0;
    00297       acc1 = 0;
    00298       acc2 = 0;
    00299       acc3 = 0;
    00300
    00301       /* read x[0], x[1], x[2] samples */
    00302       x0 = *px++;
    00303       x1 = *px++;
    00304       x2 = *px++;
    00305
    00306       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00307       k = srcBLen >> 2u;
    00308
    00309       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00310        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00311       do
    00312       {
    00313         /* Read y[0] sample */
    00314         c0 = *py++;
    00315         /* Read y[1] sample */
    00316         c1 = *py++;
    00317
    00318         /* Read x[3] sample */
    00319         x3 = *px++;
    00320
    00321         /* x[0] and x[1] are packed */
    00322         in1 = (q15_t) x0;
    00323         in2 = (q15_t) x1;
    00324
    00325         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00326
    00327         /* y[0] and y[1] are packed */
    00328         in1 = (q15_t) c0;
    00329         in2 = (q15_t) c1;
    00330
    00331         input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00332
    00333         /* acc0 += x[0] * y[0] + x[1] * y[1]  */
    00334         acc0 = __SMLAD(input1, input2, acc0);
    00335
    00336         /* x[1] and x[2] are packed */
    00337         in1 = (q15_t) x1;
    00338         in2 = (q15_t) x2;
    00339
    00340         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00341
    00342         /* acc1 += x[1] * y[0] + x[2] * y[1] */
    00343         acc1 = __SMLAD(input1, input2, acc1);
    00344
    00345         /* x[2] and x[3] are packed */
    00346         in1 = (q15_t) x2;
    00347         in2 = (q15_t) x3;
    00348
    00349         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00350
    00351         /* acc2 += x[2] * y[0] + x[3] * y[1]  */
    00352         acc2 = __SMLAD(input1, input2, acc2);
    00353
    00354         /* Read x[4] sample */
    00355         x0 = *(px++);
    00356
    00357         /* x[3] and x[4] are packed */
    00358         in1 = (q15_t) x3;
    00359         in2 = (q15_t) x0;
    00360
    00361         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00362
    00363         /* acc3 += x[3] * y[0] + x[4] * y[1]  */
    00364         acc3 = __SMLAD(input1, input2, acc3);
    00365
    00366         /* Read y[2] sample */
    00367         c0 = *py++;
    00368         /* Read y[3] sample */
    00369         c1 = *py++;
    00370
    00371         /* Read x[5] sample */
    00372         x1 = *px++;
    00373
    00374         /* x[2] and x[3] are packed */
    00375         in1 = (q15_t) x2;
    00376         in2 = (q15_t) x3;
    00377
    00378         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00379
    00380         /* y[2] and y[3] are packed */
    00381         in1 = (q15_t) c0;
    00382         in2 = (q15_t) c1;
    00383
    00384         input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00385
    00386         /* acc0 += x[2] * y[2] + x[3] * y[3]  */
    00387         acc0 = __SMLAD(input1, input2, acc0);
    00388
    00389         /* x[3] and x[4] are packed */
    00390         in1 = (q15_t) x3;
    00391         in2 = (q15_t) x0;
    00392
    00393         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00394
    00395         /* acc1 += x[3] * y[2] + x[4] * y[3]  */
    00396         acc1 = __SMLAD(input1, input2, acc1);
    00397
    00398         /* x[4] and x[5] are packed */
    00399         in1 = (q15_t) x0;
    00400         in2 = (q15_t) x1;
    00401
    00402         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00403
    00404         /* acc2 += x[4] * y[2] + x[5] * y[3]  */
    00405         acc2 = __SMLAD(input1, input2, acc2);
    00406
    00407         /* Read x[6] sample */
    00408         x2 = *px++;
    00409
    00410         /* x[5] and x[6] are packed */
    00411         in1 = (q15_t) x1;
    00412         in2 = (q15_t) x2;
    00413
    00414         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00415
    00416         /* acc3 += x[5] * y[2] + x[6] * y[3]  */
    00417         acc3 = __SMLAD(input1, input2, acc3);
    00418
    00419       } while(--k);
    00420
    00421       /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00422        ** No loop unrolling is used. */
    00423       k = srcBLen % 0x4u;
    00424
    00425       while(k > 0u)
    00426       {
    00427         /* Read y[4] sample */
    00428         c0 = *py++;
    00429
    00430         /* Read x[7] sample */
    00431         x3 = *px++;
    00432
    00433         /* Perform the multiply-accumulates */
    00434         /* acc0 +=  x[4] * y[4] */
    00435         acc0 += ((q15_t) x0 * c0);
    00436         /* acc1 +=  x[5] * y[4] */
    00437         acc1 += ((q15_t) x1 * c0);
    00438         /* acc2 +=  x[6] * y[4] */
    00439         acc2 += ((q15_t) x2 * c0);
    00440         /* acc3 +=  x[7] * y[4] */
    00441         acc3 += ((q15_t) x3 * c0);
    00442
    00443         /* Reuse the present samples for the next MAC */
    00444         x0 = x1;
    00445         x1 = x2;
    00446         x2 = x3;
    00447
    00448         /* Decrement the loop counter */
    00449         k--;
    00450       }
    00451
    00452       /* Store the result in the accumulator in the destination buffer. */
    00453       *pOut = (q7_t) (__SSAT(acc0 >> 7, 8));
    00454       /* Destination pointer is updated according to the address modifier, inc */
    00455       pOut += inc;
    00456
    00457       *pOut = (q7_t) (__SSAT(acc1 >> 7, 8));
    00458       pOut += inc;
    00459
    00460       *pOut = (q7_t) (__SSAT(acc2 >> 7, 8));
    00461       pOut += inc;
    00462
    00463       *pOut = (q7_t) (__SSAT(acc3 >> 7, 8));
    00464       pOut += inc;
    00465
    00466       /* Update the inputA and inputB pointers for next MAC calculation */
    00467       px = pIn1 + (count * 4u);
    00468       py = pIn2;
    00469
    00470       /* Increment the pointer pIn1 index, count by 1 */
    00471       count++;
    00472
    00473       /* Decrement the loop counter */
    00474       blkCnt--;
    00475     }
    00476
    00477     /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
    00478      ** No loop unrolling is used. */
    00479     blkCnt = blockSize2 % 0x4u;
    00480
    00481     while(blkCnt > 0u)
    00482     {
    00483       /* Accumulator is made zero for every iteration */
    00484       sum = 0;
    00485
    00486       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00487       k = srcBLen >> 2u;
    00488
    00489       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00490        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00491       while(k > 0u)
    00492       {
    00493         /* Reading two inputs of SrcA buffer and packing */
    00494         in1 = (q15_t) * px++;
    00495         in2 = (q15_t) * px++;
    00496         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00497
    00498         /* Reading two inputs of SrcB buffer and packing */
    00499         in1 = (q15_t) * py++;
    00500         in2 = (q15_t) * py++;
    00501         input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00502
    00503         /* Perform the multiply-accumulates */
    00504         sum = __SMLAD(input1, input2, sum);
    00505
    00506         /* Reading two inputs of SrcA buffer and packing */
    00507         in1 = (q15_t) * px++;
    00508         in2 = (q15_t) * px++;
    00509         input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00510
    00511         /* Reading two inputs of SrcB buffer and packing */
    00512         in1 = (q15_t) * py++;
    00513         in2 = (q15_t) * py++;
    00514         input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00515
    00516         /* Perform the multiply-accumulates */
    00517         sum = __SMLAD(input1, input2, sum);
    00518
    00519         /* Decrement the loop counter */
    00520         k--;
    00521       }
    00522
    00523       /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00524        ** No loop unrolling is used. */
    00525       k = srcBLen % 0x4u;
    00526
    00527       while(k > 0u)
    00528       {
    00529         /* Perform the multiply-accumulates */
    00530         sum += ((q15_t) * px++ * *py++);
    00531
    00532         /* Decrement the loop counter */
    00533         k--;
    00534       }
    00535
    00536       /* Store the result in the accumulator in the destination buffer. */
    00537       *pOut = (q7_t) (__SSAT(sum >> 7, 8));
    00538       /* Destination pointer is updated according to the address modifier, inc */
    00539       pOut += inc;
    00540
    00541       /* Update the inputA and inputB pointers for next MAC calculation */
    00542       px = pIn1 + count;
    00543       py = pIn2;
    00544
    00545       /* Increment the pointer pIn1 index, count by 1 */
    00546       count++;
    00547
    00548       /* Decrement the loop counter */
    00549       blkCnt--;
    00550     }
    00551   }
    00552   else
    00553   {
    00554     /* If the srcBLen is not a multiple of 4,
    00555      * the blockSize2 loop cannot be unrolled by 4 */
    00556     blkCnt = blockSize2;
    00557
    00558     while(blkCnt > 0u)
    00559     {
    00560       /* Accumulator is made zero for every iteration */
    00561       sum = 0;
    00562
    00563       /* Loop over srcBLen */
    00564       k = srcBLen;
    00565
    00566       while(k > 0u)
    00567       {
    00568         /* Perform the multiply-accumulate */
    00569         sum += ((q15_t) * px++ * *py++);
    00570
    00571         /* Decrement the loop counter */
    00572         k--;
    00573       }
    00574
    00575       /* Store the result in the accumulator in the destination buffer. */
    00576       *pOut = (q7_t) (__SSAT(sum >> 7, 8));
    00577       /* Destination pointer is updated according to the address modifier, inc */
    00578       pOut += inc;
    00579
    00580       /* Update the inputA and inputB pointers for next MAC calculation */
    00581       px = pIn1 + count;
    00582       py = pIn2;
    00583
    00584       /* Increment the MAC count */
    00585       count++;
    00586
    00587       /* Decrement the loop counter */
    00588       blkCnt--;
    00589     }
    00590   }
    00591
    00592   /* --------------------------
    00593    * Initializations of stage3
    00594    * -------------------------*/
    00595
    00596   /* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
    00597    * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]
    00598    * ....
    00599    * sum +=  x[srcALen-2] * y[0] + x[srcALen-1] * y[1]
    00600    * sum +=  x[srcALen-1] * y[0]
    00601    */
    00602
    00603   /* In this stage the MAC operations are decreased by 1 for every iteration.
    00604      The count variable holds the number of MAC operations performed */
    00605   count = srcBLen - 1u;
    00606
    00607   /* Working pointer of inputA */
    00608   pSrc1 = pIn1 + (srcALen - (srcBLen - 1u));
    00609   px = pSrc1;
    00610
    00611   /* Working pointer of inputB */
    00612   py = pIn2;
    00613
    00614   /* -------------------
    00615    * Stage3 process
    00616    * ------------------*/
    00617
    00618   while(blockSize3 > 0u)
    00619   {
    00620     /* Accumulator is made zero for every iteration */
    00621     sum = 0;
    00622
    00623     /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00624     k = count >> 2u;
    00625
    00626     /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00627      ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00628     while(k > 0u)
    00629     {
    00630       /* x[srcALen - srcBLen + 1] , x[srcALen - srcBLen + 2]  */
    00631       in1 = (q15_t) * px++;
    00632       in2 = (q15_t) * px++;
    00633       input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00634
    00635       /* y[0] , y[1] */
    00636       in1 = (q15_t) * py++;
    00637       in2 = (q15_t) * py++;
    00638       input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00639
    00640       /* sum += x[srcALen - srcBLen + 1] * y[0] */
    00641       /* sum += x[srcALen - srcBLen + 2] * y[1] */
    00642       sum = __SMLAD(input1, input2, sum);
    00643
    00644       /* x[srcALen - srcBLen + 3] , x[srcALen - srcBLen + 4] */
    00645       in1 = (q15_t) * px++;
    00646       in2 = (q15_t) * px++;
    00647       input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00648
    00649       /* y[2] , y[3] */
    00650       in1 = (q15_t) * py++;
    00651       in2 = (q15_t) * py++;
    00652       input2 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00653
    00654       /* sum += x[srcALen - srcBLen + 3] * y[2] */
    00655       /* sum += x[srcALen - srcBLen + 4] * y[3] */
    00656       sum = __SMLAD(input1, input2, sum);
    00657
    00658       /* Decrement the loop counter */
    00659       k--;
    00660     }
    00661
    00662     /* If the count is not a multiple of 4, compute any remaining MACs here.
    00663      ** No loop unrolling is used. */
    00664     k = count % 0x4u;
    00665
    00666     while(k > 0u)
    00667     {
    00668       /* Perform the multiply-accumulates */
    00669       sum += ((q15_t) * px++ * *py++);
    00670
    00671       /* Decrement the loop counter */
    00672       k--;
    00673     }
    00674
    00675     /* Store the result in the accumulator in the destination buffer. */
    00676     *pOut = (q7_t) (__SSAT(sum >> 7, 8));
    00677     /* Destination pointer is updated according to the address modifier, inc */
    00678     pOut += inc;
    00679
    00680     /* Update the inputA and inputB pointers for next MAC calculation */
    00681     px = ++pSrc1;
    00682     py = pIn2;
    00683
    00684     /* Decrement the MAC count */
    00685     count--;
    00686
    00687     /* Decrement the loop counter */
    00688     blockSize3--;
    00689   }
    00690
    00691 #else
    00692
    00693 /* Run the below code for Cortex-M0 */
    00694
    00695   q7_t *pIn1 = pSrcA;                            /* inputA pointer */
    00696   q7_t *pIn2 = pSrcB + (srcBLen - 1u);           /* inputB pointer */
    00697   q31_t sum;                                     /* Accumulator */
    00698   uint32_t i = 0u, j;                            /* loop counters */
    00699   uint32_t inv = 0u;                             /* Reverse order flag */
    00700   uint32_t tot = 0u;                             /* Length */
    00701
    00702   /* The algorithm implementation is based on the lengths of the inputs. */
    00703   /* srcB is always made to slide across srcA. */
    00704   /* So srcBLen is always considered as shorter or equal to srcALen */
    00705   /* But CORR(x, y) is reverse of CORR(y, x) */
    00706   /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */
    00707   /* and a varaible, inv is set to 1 */
    00708   /* If lengths are not equal then zero pad has to be done to  make the two
    00709    * inputs of same length. But to improve the performance, we include zeroes
    00710    * in the output instead of zero padding either of the the inputs*/
    00711   /* If srcALen > srcBLen, (srcALen - srcBLen) zeroes has to included in the
    00712    * starting of the output buffer */
    00713   /* If srcALen < srcBLen, (srcALen - srcBLen) zeroes has to included in the
    00714    * ending of the output buffer */
    00715   /* Once the zero padding is done the remaining of the output is calcualted
    00716    * using convolution but with the shorter signal time shifted. */
    00717
    00718   /* Calculate the length of the remaining sequence */
    00719   tot = ((srcALen + srcBLen) - 2u);
    00720
    00721   if(srcALen > srcBLen)
    00722   {
    00723     /* Calculating the number of zeros to be padded to the output */
    00724     j = srcALen - srcBLen;
    00725
    00726     /* Initialise the pointer after zero padding */
    00727     pDst += j;
    00728   }
    00729
    00730   else if(srcALen < srcBLen)
    00731   {
    00732     /* Initialization to inputB pointer */
    00733     pIn1 = pSrcB;
    00734
    00735     /* Initialization to the end of inputA pointer */
    00736     pIn2 = pSrcA + (srcALen - 1u);
    00737
    00738     /* Initialisation of the pointer after zero padding */
    00739     pDst = pDst + tot;
    00740
    00741     /* Swapping the lengths */
    00742     j = srcALen;
    00743     srcALen = srcBLen;
    00744     srcBLen = j;
    00745
    00746     /* Setting the reverse flag */
    00747     inv = 1;
    00748
    00749   }
    00750
    00751   /* Loop to calculate convolution for output length number of times */
    00752   for (i = 0u; i <= tot; i++)
    00753   {
    00754     /* Initialize sum with zero to carry on MAC operations */
    00755     sum = 0;
    00756
    00757     /* Loop to perform MAC operations according to convolution equation */
    00758     for (j = 0u; j <= i; j++)
    00759     {
    00760       /* Check the array limitations */
    00761       if((((i - j) < srcBLen) && (j < srcALen)))
    00762       {
    00763         /* z[i] += x[i-j] * y[j] */
    00764         sum += ((q15_t) pIn1[j] * pIn2[-((int32_t) i - j)]);
    00765       }
    00766     }
    00767     /* Store the output in the destination buffer */
    00768     if(inv == 1)
    00769       *pDst-- = (q7_t) __SSAT((sum >> 7u), 8u);
    00770     else
    00771       *pDst++ = (q7_t) __SSAT((sum >> 7u), 8u);
    00772   }
    00773
    00774 #endif /*   #ifndef ARM_MATH_CM0 */
    00775
    00776 }
    00777

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