Diff: src/Cortex-M4-M3/FilteringFunctions/arm_correlate_q31.c

Revision:

0:1014af42efd9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Cortex-M4-M3/FilteringFunctions/arm_correlate_q31.c	Thu Mar 10 15:07:50 2011 +0000
@@ -0,0 +1,596 @@
+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:		arm_correlate_q31.c  
+*  
+* Description:	Q31 Correlation.  
+*  
+* Target Processor: Cortex-M4/Cortex-M3
+*  
+* Version 1.0.3 2010/11/29 
+*    Re-organized the CMSIS folders and updated documentation.  
+*   
+* Version 1.0.2 2010/11/11  
+*    Documentation updated.   
+*  
+* Version 1.0.1 2010/10/05   
+*    Production release and review comments incorporated.  
+*  
+* Version 1.0.0 2010/09/20   
+*    Production release and review comments incorporated  
+*  
+* Version 0.0.7  2010/06/10   
+*    Misra-C changes done  
+*  
+* -------------------------------------------------------------------- */ 
+ 
+#include "arm_math.h" 
+ 
+/**  
+ * @ingroup groupFilters  
+ */ 
+ 
+/**  
+ * @addtogroup Corr  
+ * @{  
+ */ 
+ 
+/**  
+ * @brief Correlate Q31 sequences  
+ * @param[in] *pSrcA points to the first input sequence.  
+ * @param[in] srcALen length of the first input sequence.  
+ * @param[in] *pSrcB points to the second input sequence.  
+ * @param[in] srcBLen length of the second input sequence.  
+ * @param[out] *pDst points to the location where the output result is written.  Length 2 * max(srcALen, srcBLen) - 1.  
+ * @return none.  
+ *  
+ * @details  
+ * <b>Scaling and Overflow Behavior:</b>  
+ *  
+ * \par  
+ * The function is implemented using an internal 64-bit accumulator.  
+ * The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit.  
+ * There is no saturation on intermediate additions.  
+ * Thus, if the accumulator overflows it wraps around and distorts the result.  
+ * The input signals should be scaled down to avoid intermediate overflows.  
+ * Scale down one of the inputs by 1/min(srcALen, srcBLen)to avoid overflows since a  
+ * maximum of min(srcALen, srcBLen) number of additions is carried internally.  
+ * The 2.62 accumulator is right shifted by 31 bits and saturated to 1.31 format to yield the final result.  
+ *  
+ * \par  
+ * See <code>arm_correlate_fast_q31()</code> for a faster but less precise implementation of this function.  
+ */ 
+ 
+void arm_correlate_q31( 
+  q31_t * pSrcA, 
+  uint32_t srcALen, 
+  q31_t * pSrcB, 
+  uint32_t srcBLen, 
+  q31_t * pDst) 
+{ 
+  q31_t *pIn1;                                   /* inputA pointer               */ 
+  q31_t *pIn2;                                   /* inputB pointer               */ 
+  q31_t *pOut = pDst;                            /* output pointer               */ 
+  q31_t *px;                                     /* Intermediate inputA pointer  */ 
+  q31_t *py;                                     /* Intermediate inputB pointer  */ 
+  q31_t *pSrc1;                                  /* Intermediate pointers        */ 
+  q63_t sum, acc0, acc1, acc2, acc3;             /* Accumulators                  */ 
+  q31_t x0, x1, x2, x3, c0;                      /* temporary variables for holding input and coefficient values */ 
+  uint32_t j, k = 0u, count, blkCnt, outBlockSize, blockSize1, blockSize2, blockSize3;  /* loop counter                 */ 
+  int32_t inc = 1;                               /* Destination address modifier */ 
+ 
+ 
+  /* The algorithm implementation is based on the lengths of the inputs. */ 
+  /* srcB is always made to slide across srcA. */ 
+  /* So srcBLen is always considered as shorter or equal to srcALen */ 
+  /* But CORR(x, y) is reverse of CORR(y, x) */ 
+  /* So, when srcBLen > srcALen, output pointer is made to point to the end of the output buffer */ 
+  /* and the destination pointer modifier, inc is set to -1 */ 
+  /* If srcALen > srcBLen, zero pad has to be done to srcB to make the two inputs of same length */ 
+  /* But to improve the performance,  
+   * we include zeroes in the output instead of zero padding either of the the inputs*/ 
+  /* If srcALen > srcBLen,  
+   * (srcALen - srcBLen) zeroes has to included in the starting of the output buffer */ 
+  /* If srcALen < srcBLen,  
+   * (srcALen - srcBLen) zeroes has to included in the ending of the output buffer */ 
+  if(srcALen >= srcBLen) 
+  { 
+    /* Initialization of inputA pointer */ 
+    pIn1 = (pSrcA); 
+ 
+    /* Initialization of inputB pointer */ 
+    pIn2 = (pSrcB); 
+ 
+    /* Number of output samples is calculated */ 
+    outBlockSize = (2u * srcALen) - 1u; 
+ 
+    /* When srcALen > srcBLen, zero padding is done to srcB  
+     * to make their lengths equal.  
+     * Instead, (outBlockSize - (srcALen + srcBLen - 1))  
+     * number of output samples are made zero */ 
+    j = outBlockSize - (srcALen + (srcBLen - 1u)); 
+ 
+    while(j > 0u) 
+    { 
+      /* Zero is stored in the destination buffer */ 
+      *pOut++ = 0; 
+ 
+      /* Decrement the loop counter */ 
+      j--; 
+    } 
+ 
+  } 
+  else 
+  { 
+    /* Initialization of inputA pointer */ 
+    pIn1 = (pSrcB); 
+ 
+    /* Initialization of inputB pointer */ 
+    pIn2 = (pSrcA); 
+ 
+    /* srcBLen is always considered as shorter or equal to srcALen */ 
+    j = srcBLen; 
+    srcBLen = srcALen; 
+    srcALen = j; 
+ 
+    /* CORR(x, y) = Reverse order(CORR(y, x)) */ 
+    /* Hence set the destination pointer to point to the last output sample */ 
+    pOut = pDst + ((srcALen + srcBLen) - 2u); 
+ 
+    /* Destination address modifier is set to -1 */ 
+    inc = -1; 
+ 
+  } 
+ 
+  /* The function is internally  
+   * divided into three parts according to the number of multiplications that has to be  
+   * taken place between inputA samples and inputB samples. In the first part of the  
+   * algorithm, the multiplications increase by one for every iteration.  
+   * In the second part of the algorithm, srcBLen number of multiplications are done.  
+   * In the third part of the algorithm, the multiplications decrease by one  
+   * for every iteration.*/ 
+  /* The algorithm is implemented in three stages.  
+   * The loop counters of each stage is initiated here. */ 
+  blockSize1 = srcBLen - 1u; 
+  blockSize2 = srcALen - (srcBLen - 1u); 
+  blockSize3 = blockSize1; 
+ 
+  /* --------------------------  
+   * Initializations of stage1  
+   * -------------------------*/ 
+ 
+  /* sum = x[0] * y[srcBlen - 1]  
+   * sum = x[0] * y[srcBlen - 2] + x[1] * y[srcBlen - 1]  
+   * ....  
+   * sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen - 1] * y[srcBLen - 1]  
+   */ 
+ 
+  /* In this stage the MAC operations are increased by 1 for every iteration.  
+     The count variable holds the number of MAC operations performed */ 
+  count = 1u; 
+ 
+  /* Working pointer of inputA */ 
+  px = pIn1; 
+ 
+  /* Working pointer of inputB */ 
+  pSrc1 = pIn2 + (srcBLen - 1u); 
+  py = pSrc1; 
+ 
+  /* ------------------------  
+   * Stage1 process  
+   * ----------------------*/ 
+ 
+  /* The first stage starts here */ 
+  while(blockSize1 > 0u) 
+  { 
+    /* Accumulator is made zero for every iteration */ 
+    sum = 0; 
+ 
+    /* Apply loop unrolling and compute 4 MACs simultaneously. */ 
+    k = count >> 2; 
+ 
+    /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.  
+     ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 
+    while(k > 0u) 
+    { 
+      /* x[0] * y[srcBLen - 4] */ 
+      sum += (q63_t) * px++ * (*py++); 
+      /* x[1] * y[srcBLen - 3] */ 
+      sum += (q63_t) * px++ * (*py++); 
+      /* x[2] * y[srcBLen - 2] */ 
+      sum += (q63_t) * px++ * (*py++); 
+      /* x[3] * y[srcBLen - 1] */ 
+      sum += (q63_t) * px++ * (*py++); 
+ 
+      /* Decrement the loop counter */ 
+      k--; 
+    } 
+ 
+    /* If the count is not a multiple of 4, compute any remaining MACs here.  
+     ** No loop unrolling is used. */ 
+    k = count % 0x4u; 
+ 
+    while(k > 0u) 
+    { 
+      /* Perform the multiply-accumulates */ 
+      /* x[0] * y[srcBLen - 1] */ 
+      sum += (q63_t) * px++ * (*py++); 
+ 
+      /* Decrement the loop counter */ 
+      k--; 
+    } 
+ 
+    /* Store the result in the accumulator in the destination buffer. */ 
+    *pOut = (q31_t) (sum >> 31); 
+    /* Destination pointer is updated according to the address modifier, inc */ 
+    pOut += inc; 
+ 
+    /* Update the inputA and inputB pointers for next MAC calculation */ 
+    py = pSrc1 - count; 
+    px = pIn1; 
+ 
+    /* Increment the MAC count */ 
+    count++; 
+ 
+    /* Decrement the loop counter */ 
+    blockSize1--; 
+  } 
+ 
+  /* --------------------------  
+   * Initializations of stage2  
+   * ------------------------*/ 
+ 
+  /* sum = x[0] * y[0] + x[1] * y[1] +...+ x[srcBLen-1] * y[srcBLen-1]  
+   * sum = x[1] * y[0] + x[2] * y[1] +...+ x[srcBLen] * y[srcBLen-1]  
+   * ....  
+   * sum = x[srcALen-srcBLen-2] * y[0] + x[srcALen-srcBLen-1] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]  
+   */ 
+ 
+  /* Working pointer of inputA */ 
+  px = pIn1; 
+ 
+  /* Working pointer of inputB */ 
+  py = pIn2; 
+ 
+  /* count is index by which the pointer pIn1 to be incremented */ 
+  count = 1u; 
+ 
+  /* -------------------  
+   * Stage2 process  
+   * ------------------*/ 
+ 
+  /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.  
+   * So, to loop unroll over blockSize2,  
+   * srcBLen should be greater than or equal to 4 */ 
+  if(srcBLen >= 4u) 
+  { 
+    /* Loop unroll over blockSize2, by 4 */ 
+    blkCnt = blockSize2 >> 2u; 
+ 
+    while(blkCnt > 0u) 
+    { 
+      /* Set all accumulators to zero */ 
+      acc0 = 0; 
+      acc1 = 0; 
+      acc2 = 0; 
+      acc3 = 0; 
+ 
+      /* read x[0], x[1], x[2] samples */ 
+      x0 = *(px++); 
+      x1 = *(px++); 
+      x2 = *(px++); 
+ 
+      /* Apply loop unrolling and compute 4 MACs simultaneously. */ 
+      k = srcBLen >> 2u; 
+ 
+      /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.  
+       ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 
+      do 
+      { 
+        /* Read y[0] sample */ 
+        c0 = *(py++); 
+ 
+        /* Read x[3] sample */ 
+        x3 = *(px++); 
+ 
+        /* Perform the multiply-accumulate */ 
+        /* acc0 +=  x[0] * y[0] */ 
+        acc0 += ((q63_t) x0 * c0); 
+        /* acc1 +=  x[1] * y[0] */ 
+        acc1 += ((q63_t) x1 * c0); 
+        /* acc2 +=  x[2] * y[0] */ 
+        acc2 += ((q63_t) x2 * c0); 
+        /* acc3 +=  x[3] * y[0] */ 
+        acc3 += ((q63_t) x3 * c0); 
+ 
+        /* Read y[1] sample */ 
+        c0 = *(py++); 
+ 
+        /* Read x[4] sample */ 
+        x0 = *(px++); 
+ 
+        /* Perform the multiply-accumulates */ 
+        /* acc0 +=  x[1] * y[1] */ 
+        acc0 += ((q63_t) x1 * c0); 
+        /* acc1 +=  x[2] * y[1] */ 
+        acc1 += ((q63_t) x2 * c0); 
+        /* acc2 +=  x[3] * y[1] */ 
+        acc2 += ((q63_t) x3 * c0); 
+        /* acc3 +=  x[4] * y[1] */ 
+        acc3 += ((q63_t) x0 * c0); 
+        /* Read y[2] sample */ 
+        c0 = *(py++); 
+ 
+        /* Read x[5] sample */ 
+        x1 = *(px++); 
+ 
+        /* Perform the multiply-accumulates */ 
+        /* acc0 +=  x[2] * y[2] */ 
+        acc0 += ((q63_t) x2 * c0); 
+        /* acc1 +=  x[3] * y[2] */ 
+        acc1 += ((q63_t) x3 * c0); 
+        /* acc2 +=  x[4] * y[2] */ 
+        acc2 += ((q63_t) x0 * c0); 
+        /* acc3 +=  x[5] * y[2] */ 
+        acc3 += ((q63_t) x1 * c0); 
+ 
+        /* Read y[3] sample */ 
+        c0 = *(py++); 
+ 
+        /* Read x[6] sample */ 
+        x2 = *(px++); 
+ 
+        /* Perform the multiply-accumulates */ 
+        /* acc0 +=  x[3] * y[3] */ 
+        acc0 += ((q63_t) x3 * c0); 
+        /* acc1 +=  x[4] * y[3] */ 
+        acc1 += ((q63_t) x0 * c0); 
+        /* acc2 +=  x[5] * y[3] */ 
+        acc2 += ((q63_t) x1 * c0); 
+        /* acc3 +=  x[6] * y[3] */ 
+        acc3 += ((q63_t) x2 * c0); 
+ 
+ 
+      } while(--k); 
+ 
+      /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.  
+       ** No loop unrolling is used. */ 
+      k = srcBLen % 0x4u; 
+ 
+      while(k > 0u) 
+      { 
+        /* Read y[4] sample */ 
+        c0 = *(py++); 
+ 
+        /* Read x[7] sample */ 
+        x3 = *(px++); 
+ 
+        /* Perform the multiply-accumulates */ 
+        /* acc0 +=  x[4] * y[4] */ 
+        acc0 += ((q63_t) x0 * c0); 
+        /* acc1 +=  x[5] * y[4] */ 
+        acc1 += ((q63_t) x1 * c0); 
+        /* acc2 +=  x[6] * y[4] */ 
+        acc2 += ((q63_t) x2 * c0); 
+        /* acc3 +=  x[7] * y[4] */ 
+        acc3 += ((q63_t) x3 * c0); 
+ 
+        /* Reuse the present samples for the next MAC */ 
+        x0 = x1; 
+        x1 = x2; 
+        x2 = x3; 
+ 
+        /* Decrement the loop counter */ 
+        k--; 
+      } 
+ 
+      /* Store the result in the accumulator in the destination buffer. */ 
+      *pOut = (q31_t) (acc0 >> 31); 
+      /* Destination pointer is updated according to the address modifier, inc */ 
+      pOut += inc; 
+ 
+      *pOut = (q31_t) (acc1 >> 31); 
+      pOut += inc; 
+ 
+      *pOut = (q31_t) (acc2 >> 31); 
+      pOut += inc; 
+ 
+      *pOut = (q31_t) (acc3 >> 31); 
+      pOut += inc; 
+ 
+      /* Update the inputA and inputB pointers for next MAC calculation */ 
+      px = pIn1 + (count * 4u); 
+      py = pIn2; 
+ 
+      /* Increment the pointer pIn1 index, count by 1 */ 
+      count++; 
+ 
+      /* Decrement the loop counter */ 
+      blkCnt--; 
+    } 
+ 
+    /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.  
+     ** No loop unrolling is used. */ 
+    blkCnt = blockSize2 % 0x4u; 
+ 
+    while(blkCnt > 0u) 
+    { 
+      /* Accumulator is made zero for every iteration */ 
+      sum = 0; 
+ 
+      /* Apply loop unrolling and compute 4 MACs simultaneously. */ 
+      k = srcBLen >> 2u; 
+ 
+      /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.  
+       ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 
+      while(k > 0u) 
+      { 
+        /* Perform the multiply-accumulates */ 
+        sum += (q63_t) * px++ * (*py++); 
+        sum += (q63_t) * px++ * (*py++); 
+        sum += (q63_t) * px++ * (*py++); 
+        sum += (q63_t) * px++ * (*py++); 
+ 
+        /* Decrement the loop counter */ 
+        k--; 
+      } 
+ 
+      /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.  
+       ** No loop unrolling is used. */ 
+      k = srcBLen % 0x4u; 
+ 
+      while(k > 0u) 
+      { 
+        /* Perform the multiply-accumulate */ 
+        sum += (q63_t) * px++ * (*py++); 
+ 
+        /* Decrement the loop counter */ 
+        k--; 
+      } 
+ 
+      /* Store the result in the accumulator in the destination buffer. */ 
+      *pOut = (q31_t) (sum >> 31); 
+      /* Destination pointer is updated according to the address modifier, inc */ 
+      pOut += inc; 
+ 
+      /* Update the inputA and inputB pointers for next MAC calculation */ 
+      px = pIn1 + count; 
+      py = pIn2; 
+ 
+      /* Increment the MAC count */ 
+      count++; 
+ 
+      /* Decrement the loop counter */ 
+      blkCnt--; 
+    } 
+  } 
+  else 
+  { 
+    /* If the srcBLen is not a multiple of 4,  
+     * the blockSize2 loop cannot be unrolled by 4 */ 
+    blkCnt = blockSize2; 
+ 
+    while(blkCnt > 0u) 
+    { 
+      /* Accumulator is made zero for every iteration */ 
+      sum = 0; 
+ 
+      /* Loop over srcBLen */ 
+      k = srcBLen; 
+ 
+      while(k > 0u) 
+      { 
+        /* Perform the multiply-accumulate */ 
+        sum += (q63_t) * px++ * (*py++); 
+ 
+        /* Decrement the loop counter */ 
+        k--; 
+      } 
+ 
+      /* Store the result in the accumulator in the destination buffer. */ 
+      *pOut = (q31_t) (sum >> 31); 
+      /* Destination pointer is updated according to the address modifier, inc */ 
+      pOut += inc; 
+ 
+      /* Update the inputA and inputB pointers for next MAC calculation */ 
+      px = pIn1 + count; 
+      py = pIn2; 
+ 
+      /* Increment the MAC count */ 
+      count++; 
+ 
+      /* Decrement the loop counter */ 
+      blkCnt--; 
+    } 
+  } 
+ 
+  /* --------------------------  
+   * Initializations of stage3  
+   * -------------------------*/ 
+ 
+  /* sum += x[srcALen-srcBLen+1] * y[0] + x[srcALen-srcBLen+2] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]  
+   * sum += x[srcALen-srcBLen+2] * y[0] + x[srcALen-srcBLen+3] * y[1] +...+ x[srcALen-1] * y[srcBLen-1]  
+   * ....  
+   * sum +=  x[srcALen-2] * y[0] + x[srcALen-1] * y[1]  
+   * sum +=  x[srcALen-1] * y[0]  
+   */ 
+ 
+  /* In this stage the MAC operations are decreased by 1 for every iteration.  
+     The count variable holds the number of MAC operations performed */ 
+  count = srcBLen - 1u; 
+ 
+  /* Working pointer of inputA */ 
+  pSrc1 = pIn1 + (srcALen - (srcBLen - 1u)); 
+  px = pSrc1; 
+ 
+  /* Working pointer of inputB */ 
+  py = pIn2; 
+ 
+  /* -------------------  
+   * Stage3 process  
+   * ------------------*/ 
+ 
+  while(blockSize3 > 0u) 
+  { 
+    /* Accumulator is made zero for every iteration */ 
+    sum = 0; 
+ 
+    /* Apply loop unrolling and compute 4 MACs simultaneously. */ 
+    k = count >> 2u; 
+ 
+    /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.  
+     ** a second loop below computes MACs for the remaining 1 to 3 samples. */ 
+    while(k > 0u) 
+    { 
+      /* Perform the multiply-accumulates */ 
+      /* sum += x[srcALen - srcBLen + 4] * y[3] */ 
+      sum += (q63_t) * px++ * (*py++); 
+      /* sum += x[srcALen - srcBLen + 3] * y[2] */ 
+      sum += (q63_t) * px++ * (*py++); 
+      /* sum += x[srcALen - srcBLen + 2] * y[1] */ 
+      sum += (q63_t) * px++ * (*py++); 
+      /* sum += x[srcALen - srcBLen + 1] * y[0] */ 
+      sum += (q63_t) * px++ * (*py++); 
+ 
+      /* Decrement the loop counter */ 
+      k--; 
+    } 
+ 
+    /* If the count is not a multiple of 4, compute any remaining MACs here.  
+     ** No loop unrolling is used. */ 
+    k = count % 0x4u; 
+ 
+    while(k > 0u) 
+    { 
+      /* Perform the multiply-accumulates */ 
+      sum += (q63_t) * px++ * (*py++); 
+ 
+      /* Decrement the loop counter */ 
+      k--; 
+    } 
+ 
+    /* Store the result in the accumulator in the destination buffer. */ 
+    *pOut = (q31_t) (sum >> 31); 
+    /* Destination pointer is updated according to the address modifier, inc */ 
+    pOut += inc; 
+ 
+    /* Update the inputA and inputB pointers for next MAC calculation */ 
+    px = ++pSrc1; 
+    py = pIn2; 
+ 
+    /* Decrement the MAC count */ 
+    count--; 
+ 
+    /* Decrement the loop counter */ 
+    blockSize3--; 
+  } 
+ 
+} 
+ 
+/**  
+ * @} end of Corr group  
+ */