Diff: src/Cortex-M4-M3/FilteringFunctions/arm_fir_sparse_f32.c

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0:1014af42efd9

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+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:	    arm_fir_sparse_f32.c  
+*  
+* Description:	Floating-point sparse FIR filter processing function. 
+*  
+* Target Processor: Cortex-M4/Cortex-M3
+*  
+* 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  
+ */ 
+ 
+/**  
+ * @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.  
+ *  
+ * \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; 
+ 
+  /* 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--; 
+  } 
+ 
+} 
+ 
+/**  
+ * @} end of FIR_Sparse group  
+ */