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# arm_conv_partial_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_conv_partial_q31.c
    00009 *
    00010 * Description:  Partial convolution 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
    00059 arm_status arm_conv_partial_q31(
    00060   q31_t * pSrcA,
    00061   uint32_t srcALen,
    00062   q31_t * pSrcB,
    00063   uint32_t srcBLen,
    00064   q31_t * pDst,
    00065   uint32_t firstIndex,
    00066   uint32_t numPoints)
    00067 {
    00068
    00069
    00070 #ifndef ARM_MATH_CM0
    00071
    00072   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00073
    00074   q31_t *pIn1;                                   /* inputA pointer               */
    00075   q31_t *pIn2;                                   /* inputB pointer               */
    00076   q31_t *pOut = pDst;                            /* output pointer               */
    00077   q31_t *px;                                     /* Intermediate inputA pointer  */
    00078   q31_t *py;                                     /* Intermediate inputB pointer  */
    00079   q31_t *pSrc1, *pSrc2;                          /* Intermediate pointers        */
    00080   q63_t sum, acc0, acc1, acc2, acc3;             /* Accumulator                  */
    00081   q31_t x0, x1, x2, x3, c0;
    00082   uint32_t j, k, count, check, blkCnt;
    00083   int32_t blockSize1, blockSize2, blockSize3;    /* loop counter                 */
    00084   arm_status status;                             /* status of Partial convolution */
    00085
    00086
    00087   /* Check for range of output samples to be calculated */
    00088   if((firstIndex + numPoints) > ((srcALen + (srcBLen - 1u))))
    00089   {
    00090     /* Set status as ARM_MATH_ARGUMENT_ERROR */
    00091     status = ARM_MATH_ARGUMENT_ERROR;
    00092   }
    00093   else
    00094   {
    00095
    00096     /* The algorithm implementation is based on the lengths of the inputs. */
    00097     /* srcB is always made to slide across srcA. */
    00098     /* So srcBLen is always considered as shorter or equal to srcALen */
    00099     if(srcALen >= srcBLen)
    00100     {
    00101       /* Initialization of inputA pointer */
    00102       pIn1 = pSrcA;
    00103
    00104       /* Initialization of inputB pointer */
    00105       pIn2 = pSrcB;
    00106     }
    00107     else
    00108     {
    00109       /* Initialization of inputA pointer */
    00110       pIn1 = pSrcB;
    00111
    00112       /* Initialization of inputB pointer */
    00113       pIn2 = pSrcA;
    00114
    00115       /* srcBLen is always considered as shorter or equal to srcALen */
    00116       j = srcBLen;
    00117       srcBLen = srcALen;
    00118       srcALen = j;
    00119     }
    00120
    00121     /* Conditions to check which loopCounter holds
    00122      * the first and last indices of the output samples to be calculated. */
    00123     check = firstIndex + numPoints;
    00124     blockSize3 = ((int32_t) check - (int32_t) srcALen);
    00125     blockSize3 = (blockSize3 > 0) ? blockSize3 : 0;
    00126     blockSize1 = (((int32_t) srcBLen - 1) - (int32_t) firstIndex);
    00127     blockSize1 = (blockSize1 > 0) ? ((check > (srcBLen - 1u)) ? blockSize1 :
    00128                                      (int32_t) numPoints) : 0;
    00129     blockSize2 = (int32_t) check - ((blockSize3 + blockSize1) +
    00130                                     (int32_t) firstIndex);
    00131     blockSize2 = (blockSize2 > 0) ? blockSize2 : 0;
    00132
    00133     /* 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] */
    00134     /* The function is internally
    00135      * divided into three stages according to the number of multiplications that has to be
    00136      * taken place between inputA samples and inputB samples. In the first stage of the
    00137      * algorithm, the multiplications increase by one for every iteration.
    00138      * In the second stage of the algorithm, srcBLen number of multiplications are done.
    00139      * In the third stage of the algorithm, the multiplications decrease by one
    00140      * for every iteration. */
    00141
    00142     /* Set the output pointer to point to the firstIndex
    00143      * of the output sample to be calculated. */
    00144     pOut = pDst + firstIndex;
    00145
    00146     /* --------------------------
    00147      * Initializations of stage1
    00148      * -------------------------*/
    00149
    00150     /* sum = x[0] * y[0]
    00151      * sum = x[0] * y[1] + x[1] * y[0]
    00152      * ....
    00153      * sum = x[0] * y[srcBlen - 1] + x[1] * y[srcBlen - 2] +...+ x[srcBLen - 1] * y[0]
    00154      */
    00155
    00156     /* In this stage the MAC operations are increased by 1 for every iteration.
    00157        The count variable holds the number of MAC operations performed.
    00158        Since the partial convolution starts from firstIndex
    00159        Number of Macs to be performed is firstIndex + 1 */
    00160     count = 1u + firstIndex;
    00161
    00162     /* Working pointer of inputA */
    00163     px = pIn1;
    00164
    00165     /* Working pointer of inputB */
    00166     pSrc2 = pIn2 + firstIndex;
    00167     py = pSrc2;
    00168
    00169     /* ------------------------
    00170      * Stage1 process
    00171      * ----------------------*/
    00172
    00173     /* The first loop starts here */
    00174     while(blockSize1 > 0)
    00175     {
    00176       /* Accumulator is made zero for every iteration */
    00177       sum = 0;
    00178
    00179       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00180       k = count >> 2u;
    00181
    00182       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00183        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00184       while(k > 0u)
    00185       {
    00186         /* x[0] * y[srcBLen - 1] */
    00187         sum += (q63_t) * px++ * (*py--);
    00188         /* x[1] * y[srcBLen - 2] */
    00189         sum += (q63_t) * px++ * (*py--);
    00190         /* x[2] * y[srcBLen - 3] */
    00191         sum += (q63_t) * px++ * (*py--);
    00192         /* x[3] * y[srcBLen - 4] */
    00193         sum += (q63_t) * px++ * (*py--);
    00194
    00195         /* Decrement the loop counter */
    00196         k--;
    00197       }
    00198
    00199       /* If the count is not a multiple of 4, compute any remaining MACs here.
    00200        ** No loop unrolling is used. */
    00201       k = count % 0x4u;
    00202
    00203       while(k > 0u)
    00204       {
    00205         /* Perform the multiply-accumulate */
    00206         sum += (q63_t) * px++ * (*py--);
    00207
    00208         /* Decrement the loop counter */
    00209         k--;
    00210       }
    00211
    00212       /* Store the result in the accumulator in the destination buffer. */
    00213       *pOut++ = (q31_t) (sum >> 31);
    00214
    00215       /* Update the inputA and inputB pointers for next MAC calculation */
    00216       py = ++pSrc2;
    00217       px = pIn1;
    00218
    00219       /* Increment the MAC count */
    00220       count++;
    00221
    00222       /* Decrement the loop counter */
    00223       blockSize1--;
    00224     }
    00225
    00226     /* --------------------------
    00227      * Initializations of stage2
    00228      * ------------------------*/
    00229
    00230     /* sum = x[0] * y[srcBLen-1] + x[1] * y[srcBLen-2] +...+ x[srcBLen-1] * y[0]
    00231      * sum = x[1] * y[srcBLen-1] + x[2] * y[srcBLen-2] +...+ x[srcBLen] * y[0]
    00232      * ....
    00233      * sum = x[srcALen-srcBLen-2] * y[srcBLen-1] + x[srcALen] * y[srcBLen-2] +...+ x[srcALen-1] * y[0]
    00234      */
    00235
    00236     /* Working pointer of inputA */
    00237     px = pIn1;
    00238
    00239     /* Working pointer of inputB */
    00240     pSrc2 = pIn2 + (srcBLen - 1u);
    00241     py = pSrc2;
    00242
    00243     /* count is index by which the pointer pIn1 to be incremented */
    00244     count = 1u;
    00245
    00246     /* -------------------
    00247      * Stage2 process
    00248      * ------------------*/
    00249
    00250     /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
    00251      * So, to loop unroll over blockSize2,
    00252      * srcBLen should be greater than or equal to 4 */
    00253     if(srcBLen >= 4u)
    00254     {
    00255       /* Loop unroll over blockSize2 */
    00256       blkCnt = ((uint32_t) blockSize2 >> 2u);
    00257
    00258       while(blkCnt > 0u)
    00259       {
    00260         /* Set all accumulators to zero */
    00261         acc0 = 0;
    00262         acc1 = 0;
    00263         acc2 = 0;
    00264         acc3 = 0;
    00265
    00266         /* read x[0], x[1], x[2] samples */
    00267         x0 = *(px++);
    00268         x1 = *(px++);
    00269         x2 = *(px++);
    00270
    00271         /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00272         k = srcBLen >> 2u;
    00273
    00274         /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00275          ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00276         do
    00277         {
    00278           /* Read y[srcBLen - 1] sample */
    00279           c0 = *(py--);
    00280
    00281           /* Read x[3] sample */
    00282           x3 = *(px++);
    00283
    00284           /* Perform the multiply-accumulates */
    00285           /* acc0 +=  x[0] * y[srcBLen - 1] */
    00286           acc0 += (q63_t) x0 *c0;
    00287           /* acc1 +=  x[1] * y[srcBLen - 1] */
    00288           acc1 += (q63_t) x1 *c0;
    00289           /* acc2 +=  x[2] * y[srcBLen - 1] */
    00290           acc2 += (q63_t) x2 *c0;
    00291           /* acc3 +=  x[3] * y[srcBLen - 1] */
    00292           acc3 += (q63_t) x3 *c0;
    00293
    00294           /* Read y[srcBLen - 2] sample */
    00295           c0 = *(py--);
    00296
    00297           /* Read x[4] sample */
    00298           x0 = *(px++);
    00299
    00300           /* Perform the multiply-accumulate */
    00301           /* acc0 +=  x[1] * y[srcBLen - 2] */
    00302           acc0 += (q63_t) x1 *c0;
    00303           /* acc1 +=  x[2] * y[srcBLen - 2] */
    00304           acc1 += (q63_t) x2 *c0;
    00305           /* acc2 +=  x[3] * y[srcBLen - 2] */
    00306           acc2 += (q63_t) x3 *c0;
    00307           /* acc3 +=  x[4] * y[srcBLen - 2] */
    00308           acc3 += (q63_t) x0 *c0;
    00309
    00310           /* Read y[srcBLen - 3] sample */
    00311           c0 = *(py--);
    00312
    00313           /* Read x[5] sample */
    00314           x1 = *(px++);
    00315
    00316           /* Perform the multiply-accumulates */
    00317           /* acc0 +=  x[2] * y[srcBLen - 3] */
    00318           acc0 += (q63_t) x2 *c0;
    00319           /* acc1 +=  x[3] * y[srcBLen - 2] */
    00320           acc1 += (q63_t) x3 *c0;
    00321           /* acc2 +=  x[4] * y[srcBLen - 2] */
    00322           acc2 += (q63_t) x0 *c0;
    00323           /* acc3 +=  x[5] * y[srcBLen - 2] */
    00324           acc3 += (q63_t) x1 *c0;
    00325
    00326           /* Read y[srcBLen - 4] sample */
    00327           c0 = *(py--);
    00328
    00329           /* Read x[6] sample */
    00330           x2 = *(px++);
    00331
    00332           /* Perform the multiply-accumulates */
    00333           /* acc0 +=  x[3] * y[srcBLen - 4] */
    00334           acc0 += (q63_t) x3 *c0;
    00335           /* acc1 +=  x[4] * y[srcBLen - 4] */
    00336           acc1 += (q63_t) x0 *c0;
    00337           /* acc2 +=  x[5] * y[srcBLen - 4] */
    00338           acc2 += (q63_t) x1 *c0;
    00339           /* acc3 +=  x[6] * y[srcBLen - 4] */
    00340           acc3 += (q63_t) x2 *c0;
    00341
    00342         } while(--k);
    00343
    00344         /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00345          ** No loop unrolling is used. */
    00346         k = srcBLen % 0x4u;
    00347
    00348         while(k > 0u)
    00349         {
    00350           /* Read y[srcBLen - 5] sample */
    00351           c0 = *(py--);
    00352
    00353           /* Read x[7] sample */
    00354           x3 = *(px++);
    00355
    00356           /* Perform the multiply-accumulates */
    00357           /* acc0 +=  x[4] * y[srcBLen - 5] */
    00358           acc0 += (q63_t) x0 *c0;
    00359           /* acc1 +=  x[5] * y[srcBLen - 5] */
    00360           acc1 += (q63_t) x1 *c0;
    00361           /* acc2 +=  x[6] * y[srcBLen - 5] */
    00362           acc2 += (q63_t) x2 *c0;
    00363           /* acc3 +=  x[7] * y[srcBLen - 5] */
    00364           acc3 += (q63_t) x3 *c0;
    00365
    00366           /* Reuse the present samples for the next MAC */
    00367           x0 = x1;
    00368           x1 = x2;
    00369           x2 = x3;
    00370
    00371           /* Decrement the loop counter */
    00372           k--;
    00373         }
    00374
    00375         /* Store the result in the accumulator in the destination buffer. */
    00376         *pOut++ = (q31_t) (acc0 >> 31);
    00377         *pOut++ = (q31_t) (acc1 >> 31);
    00378         *pOut++ = (q31_t) (acc2 >> 31);
    00379         *pOut++ = (q31_t) (acc3 >> 31);
    00380
    00381         /* Update the inputA and inputB pointers for next MAC calculation */
    00382         px = pIn1 + (count * 4u);
    00383         py = pSrc2;
    00384
    00385         /* Increment the pointer pIn1 index, count by 1 */
    00386         count++;
    00387
    00388         /* Decrement the loop counter */
    00389         blkCnt--;
    00390       }
    00391
    00392       /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
    00393        ** No loop unrolling is used. */
    00394       blkCnt = (uint32_t) blockSize2 % 0x4u;
    00395
    00396       while(blkCnt > 0u)
    00397       {
    00398         /* Accumulator is made zero for every iteration */
    00399         sum = 0;
    00400
    00401         /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00402         k = srcBLen >> 2u;
    00403
    00404         /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00405          ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00406         while(k > 0u)
    00407         {
    00408           /* Perform the multiply-accumulates */
    00409           sum += (q63_t) * px++ * (*py--);
    00410           sum += (q63_t) * px++ * (*py--);
    00411           sum += (q63_t) * px++ * (*py--);
    00412           sum += (q63_t) * px++ * (*py--);
    00413
    00414           /* Decrement the loop counter */
    00415           k--;
    00416         }
    00417
    00418         /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00419          ** No loop unrolling is used. */
    00420         k = srcBLen % 0x4u;
    00421
    00422         while(k > 0u)
    00423         {
    00424           /* Perform the multiply-accumulate */
    00425           sum += (q63_t) * px++ * (*py--);
    00426
    00427           /* Decrement the loop counter */
    00428           k--;
    00429         }
    00430
    00431         /* Store the result in the accumulator in the destination buffer. */
    00432         *pOut++ = (q31_t) (sum >> 31);
    00433
    00434         /* Update the inputA and inputB pointers for next MAC calculation */
    00435         px = pIn1 + count;
    00436         py = pSrc2;
    00437
    00438         /* Increment the MAC count */
    00439         count++;
    00440
    00441         /* Decrement the loop counter */
    00442         blkCnt--;
    00443       }
    00444     }
    00445     else
    00446     {
    00447       /* If the srcBLen is not a multiple of 4,
    00448        * the blockSize2 loop cannot be unrolled by 4 */
    00449       blkCnt = (uint32_t) blockSize2;
    00450
    00451       while(blkCnt > 0u)
    00452       {
    00453         /* Accumulator is made zero for every iteration */
    00454         sum = 0;
    00455
    00456         /* srcBLen number of MACS should be performed */
    00457         k = srcBLen;
    00458
    00459         while(k > 0u)
    00460         {
    00461           /* Perform the multiply-accumulate */
    00462           sum += (q63_t) * px++ * (*py--);
    00463
    00464           /* Decrement the loop counter */
    00465           k--;
    00466         }
    00467
    00468         /* Store the result in the accumulator in the destination buffer. */
    00469         *pOut++ = (q31_t) (sum >> 31);
    00470
    00471         /* Update the inputA and inputB pointers for next MAC calculation */
    00472         px = pIn1 + count;
    00473         py = pSrc2;
    00474
    00475         /* Increment the MAC count */
    00476         count++;
    00477
    00478         /* Decrement the loop counter */
    00479         blkCnt--;
    00480       }
    00481     }
    00482
    00483
    00484     /* --------------------------
    00485      * Initializations of stage3
    00486      * -------------------------*/
    00487
    00488     /* sum += x[srcALen-srcBLen+1] * y[srcBLen-1] + x[srcALen-srcBLen+2] * y[srcBLen-2] +...+ x[srcALen-1] * y[1]
    00489      * sum += x[srcALen-srcBLen+2] * y[srcBLen-1] + x[srcALen-srcBLen+3] * y[srcBLen-2] +...+ x[srcALen-1] * y[2]
    00490      * ....
    00491      * sum +=  x[srcALen-2] * y[srcBLen-1] + x[srcALen-1] * y[srcBLen-2]
    00492      * sum +=  x[srcALen-1] * y[srcBLen-1]
    00493      */
    00494
    00495     /* In this stage the MAC operations are decreased by 1 for every iteration.
    00496        The blockSize3 variable holds the number of MAC operations performed */
    00497     count = srcBLen - 1u;
    00498
    00499     /* Working pointer of inputA */
    00500     pSrc1 = (pIn1 + srcALen) - (srcBLen - 1u);
    00501     px = pSrc1;
    00502
    00503     /* Working pointer of inputB */
    00504     pSrc2 = pIn2 + (srcBLen - 1u);
    00505     py = pSrc2;
    00506
    00507     /* -------------------
    00508      * Stage3 process
    00509      * ------------------*/
    00510
    00511     while(blockSize3 > 0)
    00512     {
    00513       /* Accumulator is made zero for every iteration */
    00514       sum = 0;
    00515
    00516       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00517       k = count >> 2u;
    00518
    00519       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00520        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00521       while(k > 0u)
    00522       {
    00523         sum += (q63_t) * px++ * (*py--);
    00524         sum += (q63_t) * px++ * (*py--);
    00525         sum += (q63_t) * px++ * (*py--);
    00526         sum += (q63_t) * px++ * (*py--);
    00527
    00528         /* Decrement the loop counter */
    00529         k--;
    00530       }
    00531
    00532       /* If the blockSize3 is not a multiple of 4, compute any remaining MACs here.
    00533        ** No loop unrolling is used. */
    00534       k = count % 0x4u;
    00535
    00536       while(k > 0u)
    00537       {
    00538         /* Perform the multiply-accumulate */
    00539         sum += (q63_t) * px++ * (*py--);
    00540
    00541         /* Decrement the loop counter */
    00542         k--;
    00543       }
    00544
    00545       /* Store the result in the accumulator in the destination buffer. */
    00546       *pOut++ = (q31_t) (sum >> 31);
    00547
    00548       /* Update the inputA and inputB pointers for next MAC calculation */
    00549       px = ++pSrc1;
    00550       py = pSrc2;
    00551
    00552       /* Decrement the MAC count */
    00553       count--;
    00554
    00555       /* Decrement the loop counter */
    00556       blockSize3--;
    00557
    00558     }
    00559
    00560     /* set status as ARM_MATH_SUCCESS */
    00561     status = ARM_MATH_SUCCESS;
    00562   }
    00563
    00564   /* Return to application */
    00565   return (status);
    00566
    00567 #else
    00568
    00569   /* Run the below code for Cortex-M0 */
    00570
    00571   q31_t *pIn1 = pSrcA;                           /* inputA pointer */
    00572   q31_t *pIn2 = pSrcB;                           /* inputB pointer */
    00573   q63_t sum;                                     /* Accumulator */
    00574   uint32_t i, j;                                 /* loop counters */
    00575   arm_status status;                             /* status of Partial convolution */
    00576
    00577   /* Check for range of output samples to be calculated */
    00578   if((firstIndex + numPoints) > ((srcALen + (srcBLen - 1u))))
    00579   {
    00580     /* Set status as ARM_ARGUMENT_ERROR */
    00581     status = ARM_MATH_ARGUMENT_ERROR;
    00582   }
    00583   else
    00584   {
    00585     /* Loop to calculate convolution for output length number of values */
    00586     for (i = firstIndex; i <= (firstIndex + numPoints - 1); i++)
    00587     {
    00588       /* Initialize sum with zero to carry on MAC operations */
    00589       sum = 0;
    00590
    00591       /* Loop to perform MAC operations according to convolution equation */
    00592       for (j = 0; j <= i; j++)
    00593       {
    00594         /* Check the array limitations */
    00595         if(((i - j) < srcBLen) && (j < srcALen))
    00596         {
    00597           /* z[i] += x[i-j] * y[j] */
    00598           sum += ((q63_t) pIn1[j] * (pIn2[i - j]));
    00599         }
    00600       }
    00601
    00602       /* Store the output in the destination buffer */
    00603       pDst[i] = (q31_t) (sum >> 31u);
    00604     }
    00605     /* set status as ARM_SUCCESS as there are no argument errors */
    00606     status = ARM_MATH_SUCCESS;
    00607   }
    00608   return (status);
    00609
    00610 #endif /*    #ifndef ARM_MATH_CM0      */
    00611
    00612 }
    00613

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