Diff: cmsis_dsp/FilteringFunctions/arm_fir_sparse_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_fir_sparse_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,370 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_fir_sparse_q31.c    
+*    
+* Description:    Q31 sparse FIR filter processing function.   
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Version 1.1.0 2012/02/15 
+*    Updated with more optimizations, bug fixes and minor API changes.  
+*   
+* 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    
+*    
+* Version 0.0.7  2010/06/10     
+*    Misra-C changes done    
+* ------------------------------------------------------------------- */
+#include "arm_math.h"
+
+
+/**    
+ * @addtogroup FIR_Sparse    
+ * @{    
+ */
+
+/**   
+ * @brief Processing function for the Q31 sparse FIR filter.   
+ * @param[in]  *S          points to an instance of the Q31 sparse FIR structure.   
+ * @param[in]  *pSrc       points to the block of input data.   
+ * @param[out] *pDst       points to the block of output data   
+ * @param[in]  *pScratchIn points to a temporary buffer of size blockSize.   
+ * @param[in]  blockSize   number of input samples to process per call.   
+ * @return none.   
+ *    
+ * <b>Scaling and Overflow Behavior:</b>    
+ * \par    
+ * The function is implemented using an internal 32-bit accumulator.   
+ * The 1.31 x 1.31 multiplications are truncated to 2.30 format.   
+ * This leads to loss of precision on the intermediate multiplications and provides only a single guard bit.    
+ * If the accumulator result overflows, it wraps around rather than saturate.   
+ * In order to avoid overflows the input signal or coefficients must be scaled down by log2(numTaps) bits.   
+ */
+
+void arm_fir_sparse_q31(
+  arm_fir_sparse_instance_q31 * S,
+  q31_t * pSrc,
+  q31_t * pDst,
+  q31_t * pScratchIn,
+  uint32_t blockSize)
+{
+
+  q31_t *pState = S->pState;                     /* State pointer */
+  q31_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
+  q31_t *px;                                     /* Scratch buffer pointer */
+  q31_t *py = pState;                            /* Temporary pointers for state buffer */
+  q31_t *pb = pScratchIn;                        /* Temporary pointers for scratch buffer */
+  q31_t *pOut;                                   /* Destination pointer */
+  q63_t out;                                     /* Temporary output variable */
+  int32_t *pTapDelay = S->pTapDelay;             /* Pointer to the array containing offset of the non-zero tap values. */
+  uint32_t delaySize = S->maxDelay + blockSize;  /* state length */
+  uint16_t numTaps = S->numTaps;                 /* Filter order */
+  int32_t readIndex;                             /* Read index of the state buffer */
+  uint32_t tapCnt, blkCnt;                       /* loop counters */
+  q31_t coeff = *pCoeffs++;                      /* Read the first coefficient value */
+  q31_t in;
+
+
+  /* BlockSize of Input samples are copied into the state buffer */
+  /* StateIndex points to the starting position to write in the state buffer */
+  arm_circularWrite_f32((int32_t *) py, delaySize, &S->stateIndex, 1,
+                        (int32_t *) pSrc, 1, blockSize);
+
+  /* Read Index, from where the state buffer should be read, is calculated. */
+  readIndex = (int32_t) (S->stateIndex - blockSize) - *pTapDelay++;
+
+  /* Wraparound of readIndex */
+  if(readIndex < 0)
+  {
+    readIndex += (int32_t) delaySize;
+  }
+
+  /* Working pointer for state buffer is updated */
+  py = pState;
+
+  /* blockSize samples are read from the state buffer */
+  arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1,
+                       (int32_t *) pb, (int32_t *) pb, blockSize, 1,
+                       blockSize);
+
+  /* Working pointer for the scratch buffer of state values */
+  px = pb;
+
+  /* Working pointer for scratch buffer of output values */
+  pOut = pDst;
+
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+  /* Loop over the blockSize. Unroll by a factor of 4.    
+   * Compute 4 Multiplications at a time. */
+  blkCnt = blockSize >> 2;
+
+  while(blkCnt > 0u)
+  {
+    /* Perform Multiplications and store in the destination buffer */
+    *pOut++ = (q31_t) (((q63_t) * px++ * coeff) >> 32);
+    *pOut++ = (q31_t) (((q63_t) * px++ * coeff) >> 32);
+    *pOut++ = (q31_t) (((q63_t) * px++ * coeff) >> 32);
+    *pOut++ = (q31_t) (((q63_t) * px++ * coeff) >> 32);
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* If the blockSize is not a multiple of 4,    
+   * compute the remaining samples */
+  blkCnt = blockSize % 0x4u;
+
+  while(blkCnt > 0u)
+  {
+    /* Perform Multiplications and store in the destination buffer */
+    *pOut++ = (q31_t) (((q63_t) * px++ * coeff) >> 32);
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* Load the coefficient value and    
+   * increment the coefficient buffer for the next set of state values */
+  coeff = *pCoeffs++;
+
+  /* Read Index, from where the state buffer should be read, is calculated. */
+  readIndex = (int32_t) (S->stateIndex - blockSize) - *pTapDelay++;
+
+  /* Wraparound of readIndex */
+  if(readIndex < 0)
+  {
+    readIndex += (int32_t) delaySize;
+  }
+
+  /* Loop over the number of taps. */
+  tapCnt = (uint32_t) numTaps - 1u;
+
+  while(tapCnt > 0u)
+  {
+    /* Working pointer for state buffer is updated */
+    py = pState;
+
+    /* blockSize samples are read from the state buffer */
+    arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1,
+                         (int32_t *) pb, (int32_t *) pb, blockSize, 1,
+                         blockSize);
+
+    /* Working pointer for the scratch buffer of state values */
+    px = pb;
+
+    /* Working pointer for scratch buffer of output values */
+    pOut = pDst;
+
+    /* Loop over the blockSize. Unroll by a factor of 4.    
+     * Compute 4 MACS at a time. */
+    blkCnt = blockSize >> 2;
+
+    while(blkCnt > 0u)
+    {
+      out = *pOut;
+      out += ((q63_t) * px++ * coeff) >> 32;
+      *pOut++ = (q31_t) (out);
+
+      out = *pOut;
+      out += ((q63_t) * px++ * coeff) >> 32;
+      *pOut++ = (q31_t) (out);
+
+      out = *pOut;
+      out += ((q63_t) * px++ * coeff) >> 32;
+      *pOut++ = (q31_t) (out);
+
+      out = *pOut;
+      out += ((q63_t) * px++ * coeff) >> 32;
+      *pOut++ = (q31_t) (out);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+
+    /* If the blockSize is not a multiple of 4,    
+     * compute the remaining samples */
+    blkCnt = blockSize % 0x4u;
+
+    while(blkCnt > 0u)
+    {
+      /* Perform Multiply-Accumulate */
+      out = *pOut;
+      out += ((q63_t) * px++ * coeff) >> 32;
+      *pOut++ = (q31_t) (out);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+
+    /* Load the coefficient value and    
+     * increment the coefficient buffer for the next set of state values */
+    coeff = *pCoeffs++;
+
+    /* Read Index, from where the state buffer should be read, is calculated. */
+    readIndex = (int32_t) (S->stateIndex - blockSize) - *pTapDelay++;
+
+    /* Wraparound of readIndex */
+    if(readIndex < 0)
+    {
+      readIndex += (int32_t) delaySize;
+    }
+
+    /* Decrement the tap loop counter */
+    tapCnt--;
+  }
+
+  /* Working output pointer is updated */
+  pOut = pDst;
+
+  /* Output is converted into 1.31 format. */
+  /* Loop over the blockSize. Unroll by a factor of 4.    
+   * process 4 output samples at a time. */
+  blkCnt = blockSize >> 2;
+
+  while(blkCnt > 0u)
+  {
+    in = *pOut << 1;
+    *pOut++ = in;
+    in = *pOut << 1;
+    *pOut++ = in;
+    in = *pOut << 1;
+    *pOut++ = in;
+    in = *pOut << 1;
+    *pOut++ = in;
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* If the blockSize is not a multiple of 4,    
+   * process the remaining output samples */
+  blkCnt = blockSize % 0x4u;
+
+  while(blkCnt > 0u)
+  {
+    in = *pOut << 1;
+    *pOut++ = in;
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+  blkCnt = blockSize;
+
+  while(blkCnt > 0u)
+  {
+    /* Perform Multiplications and store in the destination buffer */
+    *pOut++ = (q31_t) (((q63_t) * px++ * coeff) >> 32);
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* Load the coefficient value and           
+   * increment the coefficient buffer for the next set of state values */
+  coeff = *pCoeffs++;
+
+  /* Read Index, from where the state buffer should be read, is calculated. */
+  readIndex = (int32_t) (S->stateIndex - blockSize) - *pTapDelay++;
+
+  /* Wraparound of readIndex */
+  if(readIndex < 0)
+  {
+    readIndex += (int32_t) delaySize;
+  }
+
+  /* Loop over the number of taps. */
+  tapCnt = (uint32_t) numTaps - 1u;
+
+  while(tapCnt > 0u)
+  {
+    /* Working pointer for state buffer is updated */
+    py = pState;
+
+    /* blockSize samples are read from the state buffer */
+    arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1,
+                         (int32_t *) pb, (int32_t *) pb, blockSize, 1,
+                         blockSize);
+
+    /* Working pointer for the scratch buffer of state values */
+    px = pb;
+
+    /* Working pointer for scratch buffer of output values */
+    pOut = pDst;
+
+    blkCnt = blockSize;
+
+    while(blkCnt > 0u)
+    {
+      /* Perform Multiply-Accumulate */
+      out = *pOut;
+      out += ((q63_t) * px++ * coeff) >> 32;
+      *pOut++ = (q31_t) (out);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+
+    /* Load the coefficient value and           
+     * increment the coefficient buffer for the next set of state values */
+    coeff = *pCoeffs++;
+
+    /* Read Index, from where the state buffer should be read, is calculated. */
+    readIndex = (int32_t) (S->stateIndex - blockSize) - *pTapDelay++;
+
+    /* Wraparound of readIndex */
+    if(readIndex < 0)
+    {
+      readIndex += (int32_t) delaySize;
+    }
+
+    /* Decrement the tap loop counter */
+    tapCnt--;
+  }
+
+  /* Working output pointer is updated */
+  pOut = pDst;
+
+  /* Output is converted into 1.31 format. */
+  blkCnt = blockSize;
+
+  while(blkCnt > 0u)
+  {
+    in = *pOut << 1;
+    *pOut++ = in;
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+#endif /*   #ifndef ARM_MATH_CM0 */
+
+}
+
+/**    
+ * @} end of FIR_Sparse group    
+ */