CMSIS DSP library
Dependents: KL25Z_FFT_Demo Hat_Board_v5_1 KL25Z_FFT_Demo_tony KL25Z_FFT_Demo_tony ... more
Fork of mbed-dsp by
arm_correlate_q31.c
00001 /* ---------------------------------------------------------------------- 00002 * Copyright (C) 2010-2013 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 17. January 2013 00005 * $Revision: V1.4.1 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 * Redistribution and use in source and binary forms, with or without 00015 * modification, are permitted provided that the following conditions 00016 * are met: 00017 * - Redistributions of source code must retain the above copyright 00018 * notice, this list of conditions and the following disclaimer. 00019 * - Redistributions in binary form must reproduce the above copyright 00020 * notice, this list of conditions and the following disclaimer in 00021 * the documentation and/or other materials provided with the 00022 * distribution. 00023 * - Neither the name of ARM LIMITED nor the names of its contributors 00024 * may be used to endorse or promote products derived from this 00025 * software without specific prior written permission. 00026 * 00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00038 * POSSIBILITY OF SUCH DAMAGE. 00039 * -------------------------------------------------------------------- */ 00040 00041 #include "arm_math.h" 00042 00043 /** 00044 * @ingroup groupFilters 00045 */ 00046 00047 /** 00048 * @addtogroup Corr 00049 * @{ 00050 */ 00051 00052 /** 00053 * @brief Correlation of Q31 sequences. 00054 * @param[in] *pSrcA points to the first input sequence. 00055 * @param[in] srcALen length of the first input sequence. 00056 * @param[in] *pSrcB points to the second input sequence. 00057 * @param[in] srcBLen length of the second input sequence. 00058 * @param[out] *pDst points to the location where the output result is written. Length 2 * max(srcALen, srcBLen) - 1. 00059 * @return none. 00060 * 00061 * @details 00062 * <b>Scaling and Overflow Behavior:</b> 00063 * 00064 * \par 00065 * The function is implemented using an internal 64-bit accumulator. 00066 * The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit. 00067 * There is no saturation on intermediate additions. 00068 * Thus, if the accumulator overflows it wraps around and distorts the result. 00069 * The input signals should be scaled down to avoid intermediate overflows. 00070 * Scale down one of the inputs by 1/min(srcALen, srcBLen)to avoid overflows since a 00071 * maximum of min(srcALen, srcBLen) number of additions is carried internally. 00072 * The 2.62 accumulator is right shifted by 31 bits and saturated to 1.31 format to yield the final result. 00073 * 00074 * \par 00075 * See <code>arm_correlate_fast_q31()</code> for a faster but less precise implementation of this function for Cortex-M3 and Cortex-M4. 00076 */ 00077 00078 void arm_correlate_q31( 00079 q31_t * pSrcA, 00080 uint32_t srcALen, 00081 q31_t * pSrcB, 00082 uint32_t srcBLen, 00083 q31_t * pDst) 00084 { 00085 00086 #ifndef ARM_MATH_CM0_FAMILY 00087 00088 /* Run the below code for Cortex-M4 and Cortex-M3 */ 00089 00090 q31_t *pIn1; /* inputA pointer */ 00091 q31_t *pIn2; /* inputB pointer */ 00092 q31_t *pOut = pDst; /* output pointer */ 00093 q31_t *px; /* Intermediate inputA pointer */ 00094 q31_t *py; /* Intermediate inputB pointer */ 00095 q31_t *pSrc1; /* Intermediate pointers */ 00096 q63_t sum, acc0, acc1, acc2; /* Accumulators */ 00097 q31_t x0, x1, x2, c0; /* temporary variables for holding input and coefficient values */ 00098 uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3; /* loop counter */ 00099 int32_t inc = 1; /* Destination address modifier */ 00100 00101 00102 /* The algorithm implementation is based on the lengths of the inputs. */ 00103 /* srcB is always made to slide across srcA. */ 00104 /* So srcBLen is always considered as shorter or equal to srcALen */ 00105 /* But CORR(x, y) is reverse of CORR(y, x) */ 00106 /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */ 00107 /* and the destination pointer modifier, inc is set to -1 */ 00108 /* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */ 00109 /* But to improve the performance, 00110 * we include zeroes in the output instead of zero padding either of the the inputs*/ 00111 /* If srcALen > srcBLen, 00112 * (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */ 00113 /* If srcALen < srcBLen, 00114 * (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */ 00115 if(srcALen >= srcBLen) 00116 { 00117 /* Initialization of inputA pointer */ 00118 pIn1 = (pSrcA); 00119 00120 /* Initialization of inputB pointer */ 00121 pIn2 = (pSrcB); 00122 00123 /* Number of output samples is calculated */ 00124 outBlockSize = (2u * srcALen) - 1u; 00125 00126 /* When srcALen > srcBLen, zero padding is done to srcB 00127 * to make their lengths equal. 00128 * Instead, (outBlockSize - (srcALen + srcBLen - 1)) 00129 * number of output samples are made zero */ 00130 j = outBlockSize - (srcALen + (srcBLen - 1u)); 00131 00132 /* Updating the pointer position to non zero value */ 00133 pOut += j; 00134 00135 } 00136 else 00137 { 00138 /* Initialization of inputA pointer */ 00139 pIn1 = (pSrcB); 00140 00141 /* Initialization of inputB pointer */ 00142 pIn2 = (pSrcA); 00143 00144 /* srcBLen is always considered as shorter or equal to srcALen */ 00145 j = srcBLen; 00146 srcBLen = srcALen; 00147 srcALen = j; 00148 00149 /* CORR(x, y) = Reverse order(CORR(y, x)) */ 00150 /* Hence set the destination pointer to point to the last output sample */ 00151 pOut = pDst + ((srcALen + srcBLen) - 2u); 00152 00153 /* Destination address modifier is set to -1 */ 00154 inc = -1; 00155 00156 } 00157 00158 /* The function is internally 00159 * divided into three parts according to the number of multiplications that has to be 00160 * taken place between inputA samples and inputB samples. In the first part of the 00161 * algorithm, the multiplications increase by one for every iteration. 00162 * In the second part of the algorithm, srcBLen number of multiplications are done. 00163 * In the third part of the algorithm, the multiplications decrease by one 00164 * for every iteration.*/ 00165 /* The algorithm is implemented in three stages. 00166 * The loop counters of each stage is initiated here. */ 00167 blockSize1 = srcBLen - 1u; 00168 blockSize2 = srcALen - (srcBLen - 1u); 00169 blockSize3 = blockSize1; 00170 00171 /* -------------------------- 00172 * Initializations of stage1 00173 * -------------------------*/ 00174 00175 /* sum = x[0] * y[srcBlen - 1] 00176 * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1] 00177 * .... 00178 * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1] 00179 */ 00180 00181 /* In this stage the MAC operations are increased by 1 for every iteration. 00182 The count variable holds the number of MAC operations performed */ 00183 count = 1u; 00184 00185 /* Working pointer of inputA */ 00186 px = pIn1; 00187 00188 /* Working pointer of inputB */ 00189 pSrc1 = pIn2 + (srcBLen - 1u); 00190 py = pSrc1; 00191 00192 /* ------------------------ 00193 * Stage1 process 00194 * ----------------------*/ 00195 00196 /* The first stage starts here */ 00197 while(blockSize1 > 0u) 00198 { 00199 /* Accumulator is made zero for every iteration */ 00200 sum = 0; 00201 00202 /* Apply loop unrolling and compute 4 MACs simultaneously. */ 00203 k = count >> 2; 00204 00205 /* First part of the processing with loop unrolling. Compute 4 MACs at a time. 00206 ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 00207 while(k > 0u) 00208 { 00209 /* x[0] * y[srcBLen - 4] */ 00210 sum += (q63_t) * px++ * (*py++); 00211 /* x[1] * y[srcBLen - 3] */ 00212 sum += (q63_t) * px++ * (*py++); 00213 /* x[2] * y[srcBLen - 2] */ 00214 sum += (q63_t) * px++ * (*py++); 00215 /* x[3] * y[srcBLen - 1] */ 00216 sum += (q63_t) * px++ * (*py++); 00217 00218 /* Decrement the loop counter */ 00219 k--; 00220 } 00221 00222 /* If the count is not a multiple of 4, compute any remaining MACs here. 00223 ** No loop unrolling is used. */ 00224 k = count % 0x4u; 00225 00226 while(k > 0u) 00227 { 00228 /* Perform the multiply-accumulates */ 00229 /* x[0] * y[srcBLen - 1] */ 00230 sum += (q63_t) * px++ * (*py++); 00231 00232 /* Decrement the loop counter */ 00233 k--; 00234 } 00235 00236 /* Store the result in the accumulator in the destination buffer. */ 00237 *pOut = (q31_t) (sum >> 31); 00238 /* Destination pointer is updated according to the address modifier, inc */ 00239 pOut += inc; 00240 00241 /* Update the inputA and inputB pointers for next MAC calculation */ 00242 py = pSrc1 - count; 00243 px = pIn1; 00244 00245 /* Increment the MAC count */ 00246 count++; 00247 00248 /* Decrement the loop counter */ 00249 blockSize1--; 00250 } 00251 00252 /* -------------------------- 00253 * Initializations of stage2 00254 * ------------------------*/ 00255 00256 /* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1] 00257 * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1] 00258 * .... 00259 * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1] 00260 */ 00261 00262 /* Working pointer of inputA */ 00263 px = pIn1; 00264 00265 /* Working pointer of inputB */ 00266 py = pIn2; 00267 00268 /* count is index by which the pointer pIn1 to be incremented */ 00269 count = 0u; 00270 00271 /* ------------------- 00272 * Stage2 process 00273 * ------------------*/ 00274 00275 /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed. 00276 * So, to loop unroll over blockSize2, 00277 * srcBLen should be greater than or equal to 4 */ 00278 if(srcBLen >= 4u) 00279 { 00280 /* Loop unroll by 3 */ 00281 blkCnt = blockSize2 / 3; 00282 00283 while(blkCnt > 0u) 00284 { 00285 /* Set all accumulators to zero */ 00286 acc0 = 0; 00287 acc1 = 0; 00288 acc2 = 0; 00289 00290 /* read x[0], x[1] samples */ 00291 x0 = *(px++); 00292 x1 = *(px++); 00293 00294 /* Apply loop unrolling and compute 3 MACs simultaneously. */ 00295 k = srcBLen / 3; 00296 00297 /* First part of the processing with loop unrolling. Compute 3 MACs at a time. 00298 ** a second loop below computes MACs for the remaining 1 to 2 samples. */ 00299 do 00300 { 00301 /* Read y[0] sample */ 00302 c0 = *(py); 00303 00304 /* Read x[2] sample */ 00305 x2 = *(px); 00306 00307 /* Perform the multiply-accumulate */ 00308 /* acc0 += x[0] * y[0] */ 00309 acc0 += ((q63_t) x0 * c0); 00310 /* acc1 += x[1] * y[0] */ 00311 acc1 += ((q63_t) x1 * c0); 00312 /* acc2 += x[2] * y[0] */ 00313 acc2 += ((q63_t) x2 * c0); 00314 00315 /* Read y[1] sample */ 00316 c0 = *(py + 1u); 00317 00318 /* Read x[3] sample */ 00319 x0 = *(px + 1u); 00320 00321 /* Perform the multiply-accumulates */ 00322 /* acc0 += x[1] * y[1] */ 00323 acc0 += ((q63_t) x1 * c0); 00324 /* acc1 += x[2] * y[1] */ 00325 acc1 += ((q63_t) x2 * c0); 00326 /* acc2 += x[3] * y[1] */ 00327 acc2 += ((q63_t) x0 * c0); 00328 00329 /* Read y[2] sample */ 00330 c0 = *(py + 2u); 00331 00332 /* Read x[4] sample */ 00333 x1 = *(px + 2u); 00334 00335 /* Perform the multiply-accumulates */ 00336 /* acc0 += x[2] * y[2] */ 00337 acc0 += ((q63_t) x2 * c0); 00338 /* acc1 += x[3] * y[2] */ 00339 acc1 += ((q63_t) x0 * c0); 00340 /* acc2 += x[4] * y[2] */ 00341 acc2 += ((q63_t) x1 * c0); 00342 00343 /* update scratch pointers */ 00344 px += 3u; 00345 py += 3u; 00346 00347 } while(--k); 00348 00349 /* If the srcBLen is not a multiple of 3, compute any remaining MACs here. 00350 ** No loop unrolling is used. */ 00351 k = srcBLen - (3 * (srcBLen / 3)); 00352 00353 while(k > 0u) 00354 { 00355 /* Read y[4] sample */ 00356 c0 = *(py++); 00357 00358 /* Read x[7] sample */ 00359 x2 = *(px++); 00360 00361 /* Perform the multiply-accumulates */ 00362 /* acc0 += x[4] * y[4] */ 00363 acc0 += ((q63_t) x0 * c0); 00364 /* acc1 += x[5] * y[4] */ 00365 acc1 += ((q63_t) x1 * c0); 00366 /* acc2 += x[6] * y[4] */ 00367 acc2 += ((q63_t) x2 * c0); 00368 00369 /* Reuse the present samples for the next MAC */ 00370 x0 = x1; 00371 x1 = x2; 00372 00373 /* Decrement the loop counter */ 00374 k--; 00375 } 00376 00377 /* Store the result in the accumulator in the destination buffer. */ 00378 *pOut = (q31_t) (acc0 >> 31); 00379 /* Destination pointer is updated according to the address modifier, inc */ 00380 pOut += inc; 00381 00382 *pOut = (q31_t) (acc1 >> 31); 00383 pOut += inc; 00384 00385 *pOut = (q31_t) (acc2 >> 31); 00386 pOut += inc; 00387 00388 /* Increment the pointer pIn1 index, count by 3 */ 00389 count += 3u; 00390 00391 /* Update the inputA and inputB pointers for next MAC calculation */ 00392 px = pIn1 + count; 00393 py = pIn2; 00394 00395 00396 /* Decrement the loop counter */ 00397 blkCnt--; 00398 } 00399 00400 /* If the blockSize2 is not a multiple of 3, compute any remaining output samples here. 00401 ** No loop unrolling is used. */ 00402 blkCnt = blockSize2 - 3 * (blockSize2 / 3); 00403 00404 while(blkCnt > 0u) 00405 { 00406 /* Accumulator is made zero for every iteration */ 00407 sum = 0; 00408 00409 /* Apply loop unrolling and compute 4 MACs simultaneously. */ 00410 k = srcBLen >> 2u; 00411 00412 /* First part of the processing with loop unrolling. Compute 4 MACs at a time. 00413 ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 00414 while(k > 0u) 00415 { 00416 /* Perform the multiply-accumulates */ 00417 sum += (q63_t) * px++ * (*py++); 00418 sum += (q63_t) * px++ * (*py++); 00419 sum += (q63_t) * px++ * (*py++); 00420 sum += (q63_t) * px++ * (*py++); 00421 00422 /* Decrement the loop counter */ 00423 k--; 00424 } 00425 00426 /* If the srcBLen is not a multiple of 4, compute any remaining MACs here. 00427 ** No loop unrolling is used. */ 00428 k = srcBLen % 0x4u; 00429 00430 while(k > 0u) 00431 { 00432 /* Perform the multiply-accumulate */ 00433 sum += (q63_t) * px++ * (*py++); 00434 00435 /* Decrement the loop counter */ 00436 k--; 00437 } 00438 00439 /* Store the result in the accumulator in the destination buffer. */ 00440 *pOut = (q31_t) (sum >> 31); 00441 /* Destination pointer is updated according to the address modifier, inc */ 00442 pOut += inc; 00443 00444 /* Increment the MAC count */ 00445 count++; 00446 00447 /* Update the inputA and inputB pointers for next MAC calculation */ 00448 px = pIn1 + count; 00449 py = pIn2; 00450 00451 /* Decrement the loop counter */ 00452 blkCnt--; 00453 } 00454 } 00455 else 00456 { 00457 /* If the srcBLen is not a multiple of 4, 00458 * the blockSize2 loop cannot be unrolled by 4 */ 00459 blkCnt = blockSize2; 00460 00461 while(blkCnt > 0u) 00462 { 00463 /* Accumulator is made zero for every iteration */ 00464 sum = 0; 00465 00466 /* Loop over srcBLen */ 00467 k = srcBLen; 00468 00469 while(k > 0u) 00470 { 00471 /* Perform the multiply-accumulate */ 00472 sum += (q63_t) * px++ * (*py++); 00473 00474 /* Decrement the loop counter */ 00475 k--; 00476 } 00477 00478 /* Store the result in the accumulator in the destination buffer. */ 00479 *pOut = (q31_t) (sum >> 31); 00480 /* Destination pointer is updated according to the address modifier, inc */ 00481 pOut += inc; 00482 00483 /* Increment the MAC count */ 00484 count++; 00485 00486 /* Update the inputA and inputB pointers for next MAC calculation */ 00487 px = pIn1 + count; 00488 py = pIn2; 00489 00490 /* Decrement the loop counter */ 00491 blkCnt--; 00492 } 00493 } 00494 00495 /* -------------------------- 00496 * Initializations of stage3 00497 * -------------------------*/ 00498 00499 /* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1] 00500 * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1] 00501 * .... 00502 * sum += x[srcALen-2] * y[0] + x[srcALen-1] * y[1] 00503 * sum += x[srcALen-1] * y[0] 00504 */ 00505 00506 /* In this stage the MAC operations are decreased by 1 for every iteration. 00507 The count variable holds the number of MAC operations performed */ 00508 count = srcBLen - 1u; 00509 00510 /* Working pointer of inputA */ 00511 pSrc1 = pIn1 + (srcALen - (srcBLen - 1u)); 00512 px = pSrc1; 00513 00514 /* Working pointer of inputB */ 00515 py = pIn2; 00516 00517 /* ------------------- 00518 * Stage3 process 00519 * ------------------*/ 00520 00521 while(blockSize3 > 0u) 00522 { 00523 /* Accumulator is made zero for every iteration */ 00524 sum = 0; 00525 00526 /* Apply loop unrolling and compute 4 MACs simultaneously. */ 00527 k = count >> 2u; 00528 00529 /* First part of the processing with loop unrolling. Compute 4 MACs at a time. 00530 ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 00531 while(k > 0u) 00532 { 00533 /* Perform the multiply-accumulates */ 00534 /* sum += x[srcALen - srcBLen + 4] * y[3] */ 00535 sum += (q63_t) * px++ * (*py++); 00536 /* sum += x[srcALen - srcBLen + 3] * y[2] */ 00537 sum += (q63_t) * px++ * (*py++); 00538 /* sum += x[srcALen - srcBLen + 2] * y[1] */ 00539 sum += (q63_t) * px++ * (*py++); 00540 /* sum += x[srcALen - srcBLen + 1] * y[0] */ 00541 sum += (q63_t) * px++ * (*py++); 00542 00543 /* Decrement the loop counter */ 00544 k--; 00545 } 00546 00547 /* If the count is not a multiple of 4, compute any remaining MACs here. 00548 ** No loop unrolling is used. */ 00549 k = count % 0x4u; 00550 00551 while(k > 0u) 00552 { 00553 /* Perform the multiply-accumulates */ 00554 sum += (q63_t) * px++ * (*py++); 00555 00556 /* Decrement the loop counter */ 00557 k--; 00558 } 00559 00560 /* Store the result in the accumulator in the destination buffer. */ 00561 *pOut = (q31_t) (sum >> 31); 00562 /* Destination pointer is updated according to the address modifier, inc */ 00563 pOut += inc; 00564 00565 /* Update the inputA and inputB pointers for next MAC calculation */ 00566 px = ++pSrc1; 00567 py = pIn2; 00568 00569 /* Decrement the MAC count */ 00570 count--; 00571 00572 /* Decrement the loop counter */ 00573 blockSize3--; 00574 } 00575 00576 #else 00577 00578 /* Run the below code for Cortex-M0 */ 00579 00580 q31_t *pIn1 = pSrcA; /* inputA pointer */ 00581 q31_t *pIn2 = pSrcB + (srcBLen - 1u); /* inputB pointer */ 00582 q63_t sum; /* Accumulators */ 00583 uint32_t i = 0u, j; /* loop counters */ 00584 uint32_t inv = 0u; /* Reverse order flag */ 00585 uint32_t tot = 0u; /* Length */ 00586 00587 /* The algorithm implementation is based on the lengths of the inputs. */ 00588 /* srcB is always made to slide across srcA. */ 00589 /* So srcBLen is always considered as shorter or equal to srcALen */ 00590 /* But CORR(x, y) is reverse of CORR(y, x) */ 00591 /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */ 00592 /* and a varaible, inv is set to 1 */ 00593 /* If lengths are not equal then zero pad has to be done to make the two 00594 * inputs of same length. But to improve the performance, we include zeroes 00595 * in the output instead of zero padding either of the the inputs*/ 00596 /* If srcALen > srcBLen, (srcALen - srcBLen) zeroes has to included in the 00597 * starting of the output buffer */ 00598 /* If srcALen < srcBLen, (srcALen - srcBLen) zeroes has to included in the 00599 * ending of the output buffer */ 00600 /* Once the zero padding is done the remaining of the output is calcualted 00601 * using correlation but with the shorter signal time shifted. */ 00602 00603 /* Calculate the length of the remaining sequence */ 00604 tot = ((srcALen + srcBLen) - 2u); 00605 00606 if(srcALen > srcBLen) 00607 { 00608 /* Calculating the number of zeros to be padded to the output */ 00609 j = srcALen - srcBLen; 00610 00611 /* Initialise the pointer after zero padding */ 00612 pDst += j; 00613 } 00614 00615 else if(srcALen < srcBLen) 00616 { 00617 /* Initialization to inputB pointer */ 00618 pIn1 = pSrcB; 00619 00620 /* Initialization to the end of inputA pointer */ 00621 pIn2 = pSrcA + (srcALen - 1u); 00622 00623 /* Initialisation of the pointer after zero padding */ 00624 pDst = pDst + tot; 00625 00626 /* Swapping the lengths */ 00627 j = srcALen; 00628 srcALen = srcBLen; 00629 srcBLen = j; 00630 00631 /* Setting the reverse flag */ 00632 inv = 1; 00633 00634 } 00635 00636 /* Loop to calculate correlation for output length number of times */ 00637 for (i = 0u; i <= tot; i++) 00638 { 00639 /* Initialize sum with zero to carry on MAC operations */ 00640 sum = 0; 00641 00642 /* Loop to perform MAC operations according to correlation equation */ 00643 for (j = 0u; j <= i; j++) 00644 { 00645 /* Check the array limitations */ 00646 if((((i - j) < srcBLen) && (j < srcALen))) 00647 { 00648 /* z[i] += x[i-j] * y[j] */ 00649 sum += ((q63_t) pIn1[j] * pIn2[-((int32_t) i - j)]); 00650 } 00651 } 00652 /* Store the output in the destination buffer */ 00653 if(inv == 1) 00654 *pDst-- = (q31_t) (sum >> 31u); 00655 else 00656 *pDst++ = (q31_t) (sum >> 31u); 00657 } 00658 00659 #endif /* #ifndef ARM_MATH_CM0_FAMILY */ 00660 00661 } 00662 00663 /** 00664 * @} end of Corr group 00665 */
Generated on Tue Jul 12 2022 12:36:54 by 1.7.2