Diff: cmsis_dsp/FilteringFunctions/arm_correlate_fast_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_correlate_fast_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,607 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_correlate_fast_q31.c    
+*    
+* Description:    Fast Q31 Correlation.    
+*    
+* Target Processor: Cortex-M4/Cortex-M3
+*  
+* Version 1.1.0 2012/02/15 
+*    Updated with more optimizations, bug fixes and minor API changes.  
+* 
+* Version 1.0.11 2011/10/18  
+*    Bug Fix in conv, correlation, partial convolution.  
+* 
+* Version 1.0.10 2011/7/15  
+*    Big Endian support added and Merged M0 and M3/M4 Source code.   
+*    
+* 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.    
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**    
+ * @ingroup groupFilters    
+ */
+
+/**    
+ * @addtogroup Corr    
+ * @{    
+ */
+
+/**    
+ * @brief Correlation of Q31 sequences (fast version) for Cortex-M3 and Cortex-M4.    
+ * @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    
+ * This function is optimized for speed at the expense of fixed-point precision and overflow protection.    
+ * The result of each 1.31 x 1.31 multiplication is truncated to 2.30 format.    
+ * These intermediate results are accumulated in a 32-bit register in 2.30 format.    
+ * Finally, the accumulator is saturated and converted to a 1.31 result.    
+ *    
+ * \par    
+ * The fast version has the same overflow behavior as the standard version but provides less precision since it discards the low 32 bits of each multiplication result.    
+ * In order to avoid overflows completely the input signals must be scaled down.    
+ * 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.    
+ *    
+ * \par    
+ * See <code>arm_correlate_q31()</code> for a slower implementation of this function which uses 64-bit accumulation to provide higher precision.    
+ */
+
+void arm_correlate_fast_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        */
+  q31_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 */
+  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));
+
+    /* Updating the pointer position to non zero value */
+    pOut += 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 = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+      /* x[1] * y[srcBLen - 3] */
+      sum = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+      /* x[2] * y[srcBLen - 2] */
+      sum = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+      /* x[3] * y[srcBLen - 1] */
+      sum = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+
+      /* 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 = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+
+      /* Decrement the loop counter */
+      k--;
+    }
+
+    /* Store the result in the accumulator in the destination buffer. */
+    *pOut = sum << 1;
+    /* 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 = 0u;
+
+  /* -------------------    
+   * 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 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+        /* acc1 +=  x[1] * y[0] */
+        acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32);
+        /* acc2 +=  x[2] * y[0] */
+        acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+        /* acc3 +=  x[3] * y[0] */
+        acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+        /* Read y[1] sample */
+        c0 = *(py++);
+
+        /* Read x[4] sample */
+        x0 = *(px++);
+
+        /* Perform the multiply-accumulates */
+        /* acc0 +=  x[1] * y[1] */
+        acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x1 * c0)) >> 32);
+        /* acc1 +=  x[2] * y[1] */
+        acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x2 * c0)) >> 32);
+        /* acc2 +=  x[3] * y[1] */
+        acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x3 * c0)) >> 32);
+        /* acc3 +=  x[4] * y[1] */
+        acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+        /* Read y[2] sample */
+        c0 = *(py++);
+
+        /* Read x[5] sample */
+        x1 = *(px++);
+
+        /* Perform the multiply-accumulates */
+        /* acc0 +=  x[2] * y[2] */
+        acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x2 * c0)) >> 32);
+        /* acc1 +=  x[3] * y[2] */
+        acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x3 * c0)) >> 32);
+        /* acc2 +=  x[4] * y[2] */
+        acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x0 * c0)) >> 32);
+        /* acc3 +=  x[5] * y[2] */
+        acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x1 * c0)) >> 32);
+
+        /* Read y[3] sample */
+        c0 = *(py++);
+
+        /* Read x[6] sample */
+        x2 = *(px++);
+
+        /* Perform the multiply-accumulates */
+        /* acc0 +=  x[3] * y[3] */
+        acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x3 * c0)) >> 32);
+        /* acc1 +=  x[4] * y[3] */
+        acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x0 * c0)) >> 32);
+        /* acc2 +=  x[5] * y[3] */
+        acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x1 * c0)) >> 32);
+        /* acc3 +=  x[6] * y[3] */
+        acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x2 * c0)) >> 32);
+
+
+      } 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 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+        /* acc1 +=  x[5] * y[4] */
+        acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32);
+        /* acc2 +=  x[6] * y[4] */
+        acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+        /* acc3 +=  x[7] * y[4] */
+        acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+        /* 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 << 1);
+      /* Destination pointer is updated according to the address modifier, inc */
+      pOut += inc;
+
+      *pOut = (q31_t) (acc1 << 1);
+      pOut += inc;
+
+      *pOut = (q31_t) (acc2 << 1);
+      pOut += inc;
+
+      *pOut = (q31_t) (acc3 << 1);
+      pOut += inc;
+
+      /* Increment the pointer pIn1 index, count by 4 */
+      count += 4u;
+
+      /* Update the inputA and inputB pointers for next MAC calculation */
+      px = pIn1 + count;
+      py = pIn2;
+
+
+      /* 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 = (q31_t) ((((q63_t) sum << 32) +
+                        ((q63_t) * px++ * (*py++))) >> 32);
+        sum = (q31_t) ((((q63_t) sum << 32) +
+                        ((q63_t) * px++ * (*py++))) >> 32);
+        sum = (q31_t) ((((q63_t) sum << 32) +
+                        ((q63_t) * px++ * (*py++))) >> 32);
+        sum = (q31_t) ((((q63_t) sum << 32) +
+                        ((q63_t) * px++ * (*py++))) >> 32);
+
+        /* 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 = (q31_t) ((((q63_t) sum << 32) +
+                        ((q63_t) * px++ * (*py++))) >> 32);
+
+        /* Decrement the loop counter */
+        k--;
+      }
+
+      /* Store the result in the accumulator in the destination buffer. */
+      *pOut = sum << 1;
+      /* Destination pointer is updated according to the address modifier, inc */
+      pOut += inc;
+
+      /* Increment the MAC count */
+      count++;
+
+      /* Update the inputA and inputB pointers for next MAC calculation */
+      px = pIn1 + count;
+      py = pIn2;
+
+
+      /* 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 = (q31_t) ((((q63_t) sum << 32) +
+                        ((q63_t) * px++ * (*py++))) >> 32);
+
+        /* Decrement the loop counter */
+        k--;
+      }
+
+      /* Store the result in the accumulator in the destination buffer. */
+      *pOut = sum << 1;
+      /* Destination pointer is updated according to the address modifier, inc */
+      pOut += inc;
+
+      /* Increment the MAC count */
+      count++;
+
+      /* Update the inputA and inputB pointers for next MAC calculation */
+      px = pIn1 + count;
+      py = pIn2;
+
+      /* 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 = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+      /* sum += x[srcALen - srcBLen + 3] * y[2] */
+      sum = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+      /* sum += x[srcALen - srcBLen + 2] * y[1] */
+      sum = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+      /* sum += x[srcALen - srcBLen + 1] * y[0] */
+      sum = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+
+      /* 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 = (q31_t) ((((q63_t) sum << 32) +
+                      ((q63_t) * px++ * (*py++))) >> 32);
+
+      /* Decrement the loop counter */
+      k--;
+    }
+
+    /* Store the result in the accumulator in the destination buffer. */
+    *pOut = sum << 1;
+    /* 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    
+ */