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# arm_conv_partial_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_partial_f32.c
    00009 *
    00010 * Description:  Partial 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
    00074 arm_status arm_conv_partial_f32(
    00075   float32_t * pSrcA,
    00076   uint32_t srcALen,
    00077   float32_t * pSrcB,
    00078   uint32_t srcBLen,
    00079   float32_t * pDst,
    00080   uint32_t firstIndex,
    00081   uint32_t numPoints)
    00082 {
    00083
    00084
    00085 #ifndef ARM_MATH_CM0
    00086
    00087   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00088
    00089   float32_t *pIn1 = pSrcA;                       /* inputA pointer */
    00090   float32_t *pIn2 = pSrcB;                       /* inputB pointer */
    00091   float32_t *pOut = pDst;                        /* output pointer */
    00092   float32_t *px;                                 /* Intermediate inputA pointer */
    00093   float32_t *py;                                 /* Intermediate inputB pointer */
    00094   float32_t *pSrc1, *pSrc2;                      /* Intermediate pointers */
    00095   float32_t sum, acc0, acc1, acc2, acc3;         /* Accumulator */
    00096   float32_t x0, x1, x2, x3, c0;                  /* Temporary variables to hold state and coefficient values */
    00097   uint32_t j, k, count = 0u, blkCnt, check;
    00098   int32_t blockSize1, blockSize2, blockSize3;    /* loop counters */
    00099   arm_status status;                             /* status of Partial convolution */
    00100
    00101
    00102   /* Check for range of output samples to be calculated */
    00103   if((firstIndex + numPoints) > ((srcALen + (srcBLen - 1u))))
    00104   {
    00105     /* Set status as ARM_MATH_ARGUMENT_ERROR */
    00106     status = ARM_MATH_ARGUMENT_ERROR;
    00107   }
    00108   else
    00109   {
    00110
    00111     /* The algorithm implementation is based on the lengths of the inputs. */
    00112     /* srcB is always made to slide across srcA. */
    00113     /* So srcBLen is always considered as shorter or equal to srcALen */
    00114     if(srcALen >= srcBLen)
    00115     {
    00116       /* Initialization of inputA pointer */
    00117       pIn1 = pSrcA;
    00118
    00119       /* Initialization of inputB pointer */
    00120       pIn2 = pSrcB;
    00121     }
    00122     else
    00123     {
    00124       /* Initialization of inputA pointer */
    00125       pIn1 = pSrcB;
    00126
    00127       /* Initialization of inputB pointer */
    00128       pIn2 = pSrcA;
    00129
    00130       /* srcBLen is always considered as shorter or equal to srcALen */
    00131       j = srcBLen;
    00132       srcBLen = srcALen;
    00133       srcALen = j;
    00134     }
    00135
    00136     /* Conditions to check which loopCounter holds
    00137      * the first and last indices of the output samples to be calculated. */
    00138     check = firstIndex + numPoints;
    00139     blockSize3 = (int32_t) check - (int32_t) srcALen;
    00140     blockSize3 = (blockSize3 > 0) ? blockSize3 : 0;
    00141     blockSize1 = ((int32_t) srcBLen - 1) - (int32_t) firstIndex;
    00142     blockSize1 = (blockSize1 > 0) ? ((check > (srcBLen - 1u)) ? blockSize1 :
    00143                                      (int32_t) numPoints) : 0;
    00144     blockSize2 = ((int32_t) check - blockSize3) -
    00145       (blockSize1 + (int32_t) firstIndex);
    00146     blockSize2 = (blockSize2 > 0) ? blockSize2 : 0;
    00147
    00148     /* 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] */
    00149     /* The function is internally
    00150      * divided into three stages according to the number of multiplications that has to be
    00151      * taken place between inputA samples and inputB samples. In the first stage of the
    00152      * algorithm, the multiplications increase by one for every iteration.
    00153      * In the second stage of the algorithm, srcBLen number of multiplications are done.
    00154      * In the third stage of the algorithm, the multiplications decrease by one
    00155      * for every iteration. */
    00156
    00157     /* Set the output pointer to point to the firstIndex
    00158      * of the output sample to be calculated. */
    00159     pOut = pDst + firstIndex;
    00160
    00161     /* --------------------------
    00162      * Initializations of stage1
    00163      * -------------------------*/
    00164
    00165     /* sum = x[0] * y[0]
    00166      * sum = x[0] * y[1] + x[1] * y[0]
    00167      * ....
    00168      * sum = x[0] * y[srcBlen - 1] + x[1] * y[srcBlen - 2] +...+ x[srcBLen - 1] * y[0]
    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        Since the partial convolution starts from from firstIndex
    00174        Number of Macs to be performed is firstIndex + 1 */
    00175     count = 1u + firstIndex;
    00176
    00177     /* Working pointer of inputA */
    00178     px = pIn1;
    00179
    00180     /* Working pointer of inputB */
    00181     pSrc1 = pIn2 + firstIndex;
    00182     py = pSrc1;
    00183
    00184     /* ------------------------
    00185      * Stage1 process
    00186      * ----------------------*/
    00187
    00188     /* The first stage starts here */
    00189     while(blockSize1 > 0)
    00190     {
    00191       /* Accumulator is made zero for every iteration */
    00192       sum = 0.0f;
    00193
    00194       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00195       k = count >> 2u;
    00196
    00197       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00198        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00199       while(k > 0u)
    00200       {
    00201         /* x[0] * y[srcBLen - 1] */
    00202         sum += *px++ * *py--;
    00203
    00204         /* x[1] * y[srcBLen - 2] */
    00205         sum += *px++ * *py--;
    00206
    00207         /* x[2] * y[srcBLen - 3] */
    00208         sum += *px++ * *py--;
    00209
    00210         /* x[3] * y[srcBLen - 4] */
    00211         sum += *px++ * *py--;
    00212
    00213         /* Decrement the loop counter */
    00214         k--;
    00215       }
    00216
    00217       /* If the count is not a multiple of 4, compute any remaining MACs here.
    00218        ** No loop unrolling is used. */
    00219       k = count % 0x4u;
    00220
    00221       while(k > 0u)
    00222       {
    00223         /* Perform the multiply-accumulates */
    00224         sum += *px++ * *py--;
    00225
    00226         /* Decrement the loop counter */
    00227         k--;
    00228       }
    00229
    00230       /* Store the result in the accumulator in the destination buffer. */
    00231       *pOut++ = sum;
    00232
    00233       /* Update the inputA and inputB pointers for next MAC calculation */
    00234       py = ++pSrc1;
    00235       px = pIn1;
    00236
    00237       /* Increment the MAC count */
    00238       count++;
    00239
    00240       /* Decrement the loop counter */
    00241       blockSize1--;
    00242     }
    00243
    00244     /* --------------------------
    00245      * Initializations of stage2
    00246      * ------------------------*/
    00247
    00248     /* sum = x[0] * y[srcBLen-1] + x[1] * y[srcBLen-2] +...+ x[srcBLen-1] * y[0]
    00249      * sum = x[1] * y[srcBLen-1] + x[2] * y[srcBLen-2] +...+ x[srcBLen] * y[0]
    00250      * ....
    00251      * sum = x[srcALen-srcBLen-2] * y[srcBLen-1] + x[srcALen] * y[srcBLen-2] +...+ x[srcALen-1] * y[0]
    00252      */
    00253
    00254     /* Working pointer of inputA */
    00255     px = pIn1;
    00256
    00257     /* Working pointer of inputB */
    00258     pSrc2 = pIn2 + (srcBLen - 1u);
    00259     py = pSrc2;
    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 = ((uint32_t) blockSize2 >> 2u);
    00275
    00276       while(blkCnt > 0u)
    00277       {
    00278         /* Set all accumulators to zero */
    00279         acc0 = 0.0f;
    00280         acc1 = 0.0f;
    00281         acc2 = 0.0f;
    00282         acc3 = 0.0f;
    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[srcBLen - 1] sample */
    00297           c0 = *(py--);
    00298
    00299           /* Read x[3] sample */
    00300           x3 = *(px++);
    00301
    00302           /* Perform the multiply-accumulate */
    00303           /* acc0 +=  x[0] * y[srcBLen - 1] */
    00304           acc0 += x0 * c0;
    00305
    00306           /* acc1 +=  x[1] * y[srcBLen - 1] */
    00307           acc1 += x1 * c0;
    00308
    00309           /* acc2 +=  x[2] * y[srcBLen - 1] */
    00310           acc2 += x2 * c0;
    00311
    00312           /* acc3 +=  x[3] * y[srcBLen - 1] */
    00313           acc3 += x3 * c0;
    00314
    00315           /* Read y[srcBLen - 2] sample */
    00316           c0 = *(py--);
    00317
    00318           /* Read x[4] sample */
    00319           x0 = *(px++);
    00320
    00321           /* Perform the multiply-accumulate */
    00322           /* acc0 +=  x[1] * y[srcBLen - 2] */
    00323           acc0 += x1 * c0;
    00324           /* acc1 +=  x[2] * y[srcBLen - 2] */
    00325           acc1 += x2 * c0;
    00326           /* acc2 +=  x[3] * y[srcBLen - 2] */
    00327           acc2 += x3 * c0;
    00328           /* acc3 +=  x[4] * y[srcBLen - 2] */
    00329           acc3 += x0 * c0;
    00330
    00331           /* Read y[srcBLen - 3] sample */
    00332           c0 = *(py--);
    00333
    00334           /* Read x[5] sample */
    00335           x1 = *(px++);
    00336
    00337           /* Perform the multiply-accumulates */
    00338           /* acc0 +=  x[2] * y[srcBLen - 3] */
    00339           acc0 += x2 * c0;
    00340           /* acc1 +=  x[3] * y[srcBLen - 2] */
    00341           acc1 += x3 * c0;
    00342           /* acc2 +=  x[4] * y[srcBLen - 2] */
    00343           acc2 += x0 * c0;
    00344           /* acc3 +=  x[5] * y[srcBLen - 2] */
    00345           acc3 += x1 * c0;
    00346
    00347           /* Read y[srcBLen - 4] sample */
    00348           c0 = *(py--);
    00349
    00350           /* Read x[6] sample */
    00351           x2 = *(px++);
    00352
    00353           /* Perform the multiply-accumulates */
    00354           /* acc0 +=  x[3] * y[srcBLen - 4] */
    00355           acc0 += x3 * c0;
    00356           /* acc1 +=  x[4] * y[srcBLen - 4] */
    00357           acc1 += x0 * c0;
    00358           /* acc2 +=  x[5] * y[srcBLen - 4] */
    00359           acc2 += x1 * c0;
    00360           /* acc3 +=  x[6] * y[srcBLen - 4] */
    00361           acc3 += x2 * c0;
    00362
    00363
    00364         } while(--k);
    00365
    00366         /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00367          ** No loop unrolling is used. */
    00368         k = srcBLen % 0x4u;
    00369
    00370         while(k > 0u)
    00371         {
    00372           /* Read y[srcBLen - 5] sample */
    00373           c0 = *(py--);
    00374
    00375           /* Read x[7] sample */
    00376           x3 = *(px++);
    00377
    00378           /* Perform the multiply-accumulates */
    00379           /* acc0 +=  x[4] * y[srcBLen - 5] */
    00380           acc0 += x0 * c0;
    00381           /* acc1 +=  x[5] * y[srcBLen - 5] */
    00382           acc1 += x1 * c0;
    00383           /* acc2 +=  x[6] * y[srcBLen - 5] */
    00384           acc2 += x2 * c0;
    00385           /* acc3 +=  x[7] * y[srcBLen - 5] */
    00386           acc3 += x3 * c0;
    00387
    00388           /* Reuse the present samples for the next MAC */
    00389           x0 = x1;
    00390           x1 = x2;
    00391           x2 = x3;
    00392
    00393           /* Decrement the loop counter */
    00394           k--;
    00395         }
    00396
    00397         /* Store the result in the accumulator in the destination buffer. */
    00398         *pOut++ = acc0;
    00399         *pOut++ = acc1;
    00400         *pOut++ = acc2;
    00401         *pOut++ = acc3;
    00402
    00403         /* Update the inputA and inputB pointers for next MAC calculation */
    00404         px = pIn1 + (count * 4u);
    00405         py = pSrc2;
    00406
    00407         /* Increment the pointer pIn1 index, count by 1 */
    00408         count++;
    00409
    00410         /* Decrement the loop counter */
    00411         blkCnt--;
    00412       }
    00413
    00414       /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
    00415        ** No loop unrolling is used. */
    00416       blkCnt = (uint32_t) blockSize2 % 0x4u;
    00417
    00418       while(blkCnt > 0u)
    00419       {
    00420         /* Accumulator is made zero for every iteration */
    00421         sum = 0.0f;
    00422
    00423         /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00424         k = srcBLen >> 2u;
    00425
    00426         /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00427          ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00428         while(k > 0u)
    00429         {
    00430           /* Perform the multiply-accumulates */
    00431           sum += *px++ * *py--;
    00432           sum += *px++ * *py--;
    00433           sum += *px++ * *py--;
    00434           sum += *px++ * *py--;
    00435
    00436           /* Decrement the loop counter */
    00437           k--;
    00438         }
    00439
    00440         /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
    00441          ** No loop unrolling is used. */
    00442         k = srcBLen % 0x4u;
    00443
    00444         while(k > 0u)
    00445         {
    00446           /* Perform the multiply-accumulate */
    00447           sum += *px++ * *py--;
    00448
    00449           /* Decrement the loop counter */
    00450           k--;
    00451         }
    00452
    00453         /* Store the result in the accumulator in the destination buffer. */
    00454         *pOut++ = sum;
    00455
    00456         /* Update the inputA and inputB pointers for next MAC calculation */
    00457         px = pIn1 + count;
    00458         py = pSrc2;
    00459
    00460         /* Increment the MAC count */
    00461         count++;
    00462
    00463         /* Decrement the loop counter */
    00464         blkCnt--;
    00465       }
    00466     }
    00467     else
    00468     {
    00469       /* If the srcBLen is not a multiple of 4,
    00470        * the blockSize2 loop cannot be unrolled by 4 */
    00471       blkCnt = (uint32_t) blockSize2;
    00472
    00473       while(blkCnt > 0u)
    00474       {
    00475         /* Accumulator is made zero for every iteration */
    00476         sum = 0.0f;
    00477
    00478         /* srcBLen number of MACS should be performed */
    00479         k = srcBLen;
    00480
    00481         while(k > 0u)
    00482         {
    00483           /* Perform the multiply-accumulate */
    00484           sum += *px++ * *py--;
    00485
    00486           /* Decrement the loop counter */
    00487           k--;
    00488         }
    00489
    00490         /* Store the result in the accumulator in the destination buffer. */
    00491         *pOut++ = sum;
    00492
    00493         /* Update the inputA and inputB pointers for next MAC calculation */
    00494         px = pIn1 + count;
    00495         py = pSrc2;
    00496
    00497         /* Increment the MAC count */
    00498         count++;
    00499
    00500         /* Decrement the loop counter */
    00501         blkCnt--;
    00502       }
    00503     }
    00504
    00505
    00506     /* --------------------------
    00507      * Initializations of stage3
    00508      * -------------------------*/
    00509
    00510     /* sum += x[srcALen-srcBLen+1] * y[srcBLen-1] + x[srcALen-srcBLen+2] * y[srcBLen-2] +...+ x[srcALen-1] * y[1]
    00511      * sum += x[srcALen-srcBLen+2] * y[srcBLen-1] + x[srcALen-srcBLen+3] * y[srcBLen-2] +...+ x[srcALen-1] * y[2]
    00512      * ....
    00513      * sum +=  x[srcALen-2] * y[srcBLen-1] + x[srcALen-1] * y[srcBLen-2]
    00514      * sum +=  x[srcALen-1] * y[srcBLen-1]
    00515      */
    00516
    00517     /* In this stage the MAC operations are decreased by 1 for every iteration.
    00518        The count variable holds the number of MAC operations performed */
    00519     count = srcBLen - 1u;
    00520
    00521     /* Working pointer of inputA */
    00522     pSrc1 = (pIn1 + srcALen) - (srcBLen - 1u);
    00523     px = pSrc1;
    00524
    00525     /* Working pointer of inputB */
    00526     pSrc2 = pIn2 + (srcBLen - 1u);
    00527     py = pSrc2;
    00528
    00529     while(blockSize3 > 0)
    00530     {
    00531       /* Accumulator is made zero for every iteration */
    00532       sum = 0.0f;
    00533
    00534       /* Apply loop unrolling and compute 4 MACs simultaneously. */
    00535       k = count >> 2u;
    00536
    00537       /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
    00538        ** a second loop below computes MACs for the remaining 1 to 3 samples. */
    00539       while(k > 0u)
    00540       {
    00541         /* sum += x[srcALen - srcBLen + 1] * y[srcBLen - 1] */
    00542         sum += *px++ * *py--;
    00543
    00544         /* sum += x[srcALen - srcBLen + 2] * y[srcBLen - 2] */
    00545         sum += *px++ * *py--;
    00546
    00547         /* sum += x[srcALen - srcBLen + 3] * y[srcBLen - 3] */
    00548         sum += *px++ * *py--;
    00549
    00550         /* sum += x[srcALen - srcBLen + 4] * y[srcBLen - 4] */
    00551         sum += *px++ * *py--;
    00552
    00553         /* Decrement the loop counter */
    00554         k--;
    00555       }
    00556
    00557       /* If the count is not a multiple of 4, compute any remaining MACs here.
    00558        ** No loop unrolling is used. */
    00559       k = count % 0x4u;
    00560
    00561       while(k > 0u)
    00562       {
    00563         /* Perform the multiply-accumulates */
    00564         /* sum +=  x[srcALen-1] * y[srcBLen-1] */
    00565         sum += *px++ * *py--;
    00566
    00567         /* Decrement the loop counter */
    00568         k--;
    00569       }
    00570
    00571       /* Store the result in the accumulator in the destination buffer. */
    00572       *pOut++ = sum;
    00573
    00574       /* Update the inputA and inputB pointers for next MAC calculation */
    00575       px = ++pSrc1;
    00576       py = pSrc2;
    00577
    00578       /* Decrement the MAC count */
    00579       count--;
    00580
    00581       /* Decrement the loop counter */
    00582       blockSize3--;
    00583
    00584     }
    00585
    00586     /* set status as ARM_MATH_SUCCESS */
    00587     status = ARM_MATH_SUCCESS;
    00588   }
    00589
    00590   /* Return to application */
    00591   return (status);
    00592
    00593 #else
    00594
    00595   /* Run the below code for Cortex-M0 */
    00596
    00597   float32_t *pIn1 = pSrcA;                       /* inputA pointer */
    00598   float32_t *pIn2 = pSrcB;                       /* inputB pointer */
    00599   float32_t sum;                                 /* Accumulator */
    00600   uint32_t i, j;                                 /* loop counters */
    00601   arm_status status;                             /* status of Partial convolution */
    00602
    00603   /* Check for range of output samples to be calculated */
    00604   if((firstIndex + numPoints) > ((srcALen + (srcBLen - 1u))))
    00605   {
    00606     /* Set status as ARM_ARGUMENT_ERROR */
    00607     status = ARM_MATH_ARGUMENT_ERROR;
    00608   }
    00609   else
    00610   {
    00611     /* Loop to calculate convolution for output length number of values */
    00612     for (i = firstIndex; i <= (firstIndex + numPoints - 1); i++)
    00613     {
    00614       /* Initialize sum with zero to carry on MAC operations */
    00615       sum = 0.0f;
    00616
    00617       /* Loop to perform MAC operations according to convolution equation */
    00618       for (j = 0u; j <= i; j++)
    00619       {
    00620         /* Check the array limitations for inputs */
    00621         if((((i - j) < srcBLen) && (j < srcALen)))
    00622         {
    00623           /* z[i] += x[i-j] * y[j] */
    00624           sum += pIn1[j] * pIn2[i - j];
    00625         }
    00626       }
    00627       /* Store the output in the destination buffer */
    00628       pDst[i] = sum;
    00629     }
    00630     /* set status as ARM_SUCCESS as there are no argument errors */
    00631     status = ARM_MATH_SUCCESS;
    00632   }
    00633   return (status);
    00634
    00635 #endif /*   #ifndef ARM_MATH_CM0 */
    00636
    00637 }
    00638

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