Diff: FilteringFunctions/arm_fir_sparse_f32.c

Revision:

0:3d9c67d97d6f

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+++ b/FilteringFunctions/arm_fir_sparse_f32.c	Mon Jul 28 15:03:15 2014 +0000
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+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
+*    
+* $Date:        12. March 2014
+* $Revision: 	V1.4.3
+*    
+* Project: 	    CMSIS DSP Library    
+* Title:	    arm_fir_sparse_f32.c    
+*    
+* Description:	Floating-point sparse FIR filter processing function.   
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Redistribution and use in source and binary forms, with or without 
+* modification, are permitted provided that the following conditions
+* are met:
+*   - Redistributions of source code must retain the above copyright
+*     notice, this list of conditions and the following disclaimer.
+*   - Redistributions in binary form must reproduce the above copyright
+*     notice, this list of conditions and the following disclaimer in
+*     the documentation and/or other materials provided with the 
+*     distribution.
+*   - Neither the name of ARM LIMITED nor the names of its contributors
+*     may be used to endorse or promote products derived from this
+*     software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.    
+* ------------------------------------------------------------------- */
+#include "arm_math.h"
+
+/**    
+ * @ingroup groupFilters    
+ */
+
+/**    
+ * @defgroup FIR_Sparse Finite Impulse Response (FIR) Sparse Filters    
+ *    
+ * This group of functions implements sparse FIR filters.     
+ * Sparse FIR filters are equivalent to standard FIR filters except that most of the coefficients are equal to zero.   
+ * Sparse filters are used for simulating reflections in communications and audio applications.   
+ *   
+ * There are separate functions for Q7, Q15, Q31, and floating-point data types.    
+ * The functions operate on blocks  of input and output data and each call to the function processes    
+ * <code>blockSize</code> samples through the filter.  <code>pSrc</code> and    
+ * <code>pDst</code> points to input and output arrays respectively containing <code>blockSize</code> values.    
+ *    
+ * \par Algorithm:    
+ * The sparse filter instant structure contains an array of tap indices <code>pTapDelay</code> which specifies the locations of the non-zero coefficients.   
+ * This is in addition to the coefficient array <code>b</code>.   
+ * The implementation essentially skips the multiplications by zero and leads to an efficient realization.   
+ * <pre>   
+ *     y[n] = b[0] * x[n-pTapDelay[0]] + b[1] * x[n-pTapDelay[1]] + b[2] * x[n-pTapDelay[2]] + ...+ b[numTaps-1] * x[n-pTapDelay[numTaps-1]]    
+ * </pre>    
+ * \par    
+ * \image html FIRSparse.gif "Sparse FIR filter.  b[n] represents the filter coefficients"   
+ * \par    
+ * <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>;    
+ * <code>pTapDelay</code> points to an array of nonzero indices and is also of size <code>numTaps</code>;   
+ * <code>pState</code> points to a state array of size <code>maxDelay + blockSize</code>, where   
+ * <code>maxDelay</code> is the largest offset value that is ever used in the <code>pTapDelay</code> array.   
+ * Some of the processing functions also require temporary working buffers.   
+ *   
+ * \par Instance Structure    
+ * The coefficients and state variables for a filter are stored together in an instance data structure.    
+ * A separate instance structure must be defined for each filter.    
+ * Coefficient and offset arrays may be shared among several instances while state variable arrays cannot be shared.    
+ * There are separate instance structure declarations for each of the 4 supported data types.    
+ *    
+ * \par Initialization Functions    
+ * There is also an associated initialization function for each data type.    
+ * The initialization function performs the following operations:    
+ * - Sets the values of the internal structure fields.    
+ * - Zeros out the values in the state buffer.    
+ * To do this manually without calling the init function, assign the follow subfields of the instance structure:
+ * numTaps, pCoeffs, pTapDelay, maxDelay, stateIndex, pState. Also set all of the values in pState to zero. 
+ *    
+ * \par    
+ * Use of the initialization function is optional.    
+ * However, if the initialization function is used, then the instance structure cannot be placed into a const data section.    
+ * To place an instance structure into a const data section, the instance structure must be manually initialized.    
+ * Set the values in the state buffer to zeros before static initialization.    
+ * The code below statically initializes each of the 4 different data type filter instance structures    
+ * <pre>    
+ *arm_fir_sparse_instance_f32 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};    
+ *arm_fir_sparse_instance_q31 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};    
+ *arm_fir_sparse_instance_q15 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};    
+ *arm_fir_sparse_instance_q7 S =  {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};    
+ * </pre>    
+ * \par    
+ *    
+ * \par Fixed-Point Behavior    
+ * Care must be taken when using the fixed-point versions of the sparse FIR filter functions.    
+ * In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.    
+ * Refer to the function specific documentation below for usage guidelines.    
+ */
+
+/**    
+ * @addtogroup FIR_Sparse    
+ * @{    
+ */
+
+/**   
+ * @brief Processing function for the floating-point sparse FIR filter.   
+ * @param[in]  *S          points to an instance of the floating-point 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.   
+ */
+
+void arm_fir_sparse_f32(
+  arm_fir_sparse_instance_f32 * S,
+  float32_t * pSrc,
+  float32_t * pDst,
+  float32_t * pScratchIn,
+  uint32_t blockSize)
+{
+
+  float32_t *pState = S->pState;                 /* State pointer */
+  float32_t *pCoeffs = S->pCoeffs;               /* Coefficient pointer */
+  float32_t *px;                                 /* Scratch buffer pointer */
+  float32_t *py = pState;                        /* Temporary pointers for state buffer */
+  float32_t *pb = pScratchIn;                    /* Temporary pointers for scratch buffer */
+  float32_t *pOut;                               /* Destination pointer */
+  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;                 /* Number of filter coefficients in the filter  */
+  int32_t readIndex;                             /* Read index of the state buffer */
+  uint32_t tapCnt, blkCnt;                       /* loop counters */
+  float32_t coeff = *pCoeffs++;                  /* Read the first coefficient value */
+
+
+
+  /* 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 - (int32_t) 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 */
+  px = pb;
+
+  /* Working pointer for destination buffer */
+  pOut = pDst;
+
+
+#ifndef ARM_MATH_CM0_FAMILY
+
+  /* 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 >> 2u;
+
+  while(blkCnt > 0u)
+  {
+    /* Perform Multiplications and store in destination buffer */
+    *pOut++ = *px++ * coeff;
+    *pOut++ = *px++ * coeff;
+    *pOut++ = *px++ * coeff;
+    *pOut++ = *px++ * coeff;
+
+    /* 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 destination buffer */
+    *pOut++ = *px++ * coeff;
+
+    /* 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 - (int32_t) 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 */
+    px = pb;
+
+    /* Working pointer for destination buffer */
+    pOut = pDst;
+
+    /* Loop over the blockSize. Unroll by a factor of 4.    
+     * Compute 4 MACS at a time. */
+    blkCnt = blockSize >> 2u;
+
+    while(blkCnt > 0u)
+    {
+      /* Perform Multiply-Accumulate */
+      *pOut++ += *px++ * coeff;
+      *pOut++ += *px++ * coeff;
+      *pOut++ += *px++ * coeff;
+      *pOut++ += *px++ * coeff;
+
+      /* 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 */
+      *pOut++ += *px++ * coeff;
+
+      /* 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 -
+                 (int32_t) blockSize) - *pTapDelay++;
+
+    /* Wraparound of readIndex */
+    if(readIndex < 0)
+    {
+      readIndex += (int32_t) delaySize;
+    }
+
+    /* Decrement the tap loop counter */
+    tapCnt--;
+  }
+
+#else
+
+/* Run the below code for Cortex-M0 */
+
+  blkCnt = blockSize;
+
+  while(blkCnt > 0u)
+  {
+    /* Perform Multiplications and store in destination buffer */
+    *pOut++ = *px++ * coeff;
+
+    /* 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 - (int32_t) 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 */
+    px = pb;
+
+    /* Working pointer for destination buffer */
+    pOut = pDst;
+
+    blkCnt = blockSize;
+
+    while(blkCnt > 0u)
+    {
+      /* Perform Multiply-Accumulate */
+      *pOut++ += *px++ * coeff;
+
+      /* 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 - (int32_t) blockSize) - *pTapDelay++;
+
+    /* Wraparound of readIndex */
+    if(readIndex < 0)
+    {
+      readIndex += (int32_t) delaySize;
+    }
+
+    /* Decrement the tap loop counter */
+    tapCnt--;
+  }
+
+#endif /*   #ifndef ARM_MATH_CM0_FAMILY        */
+
+}
+
+/**    
+ * @} end of FIR_Sparse group    
+ */