Diff: src/Cortex-M4-M3/FilteringFunctions/arm_fir_sparse_q15.c

Revision:

0:1014af42efd9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Cortex-M4-M3/FilteringFunctions/arm_fir_sparse_q15.c	Thu Mar 10 15:07:50 2011 +0000
@@ -0,0 +1,255 @@
+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:	    arm_fir_sparse_q15.c  
+*  
+* Description:	Q15 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" 
+ 
+/**  
+ * @addtogroup FIR_Sparse  
+ * @{  
+ */ 
+ 
+/** 
+ * @brief Processing function for the Q15 sparse FIR filter. 
+ * @param[in]  *S           points to an instance of the Q15 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]  *pScratchOut 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 1.15 x 1.15 multiplications yield a 2.30 result and these are added to a 2.30 accumulator. 
+ * Thus the full precision of the multiplications is maintained but there is only a single guard bit in the accumulator. 
+ * If the accumulator result overflows it will wrap around rather than saturate. 
+ * After all multiply-accumulates are performed, the 2.30 accumulator is truncated to 2.15 format and then saturated to 1.15 format.  
+ * In order to avoid overflows the input signal or coefficients must be scaled down by log2(numTaps) bits. 
+ */ 
+ 
+ 
+void arm_fir_sparse_q15( 
+  arm_fir_sparse_instance_q15 * S, 
+  q15_t * pSrc, 
+  q15_t * pDst, 
+  q15_t * pScratchIn, 
+  q31_t * pScratchOut, 
+  uint32_t blockSize) 
+{ 
+ 
+  q15_t *pState = S->pState;                     /* State pointer */ 
+  q15_t *pIn = (q15_t *) pSrc;                   /* Working pointer for input */ 
+  q15_t *pOut = pDst;                            /* Working pointer for output */ 
+  q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */ 
+  q15_t *px;                                     /* Temporary pointers for scratch buffer */ 
+  q15_t *pb = pScratchIn;                        /* Temporary pointers for scratch buffer */ 
+  q15_t *py = pState;                            /* Temporary pointers for state buffer */ 
+  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 */ 
+  q15_t coeff = *pCoeffs++;                      /* Read the first coefficient value */ 
+  q31_t *pScr2 = pScratchOut;                    /* Working pointer for pScratchOut */ 
+  q31_t in1, in2;                                /* Temporary variables */ 
+ 
+ 
+ 
+  /* BlockSize of Input samples are copied into the state buffer */ 
+  /* StateIndex points to the starting position to write in the state buffer */ 
+  arm_circularWrite_q15(py, delaySize, &S->stateIndex, 1, pIn, 1, blockSize); 
+ 
+  /* Loop over the number of taps. */ 
+  tapCnt = numTaps; 
+ 
+  /* Read Index, from where the state buffer should be read, is calculated. */ 
+  readIndex = (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_q15(py, delaySize, &readIndex, 1, 
+                       pb, pb, blockSize, 1, blockSize); 
+ 
+  /* Working pointer for the scratch buffer of state values */ 
+  px = pb; 
+ 
+  /* Working pointer for scratch buffer of output values */ 
+  pScratchOut = pScr2; 
+ 
+  /* Loop over the blockSize. Unroll by a factor of 4.  
+   * Compute 4 multiplications at a time. */ 
+  blkCnt = blockSize >> 2; 
+ 
+  while(blkCnt > 0u) 
+  { 
+    /* Perform multiplication and store in the scratch buffer */ 
+    *pScratchOut++ = ((q31_t) * px++ * coeff); 
+    *pScratchOut++ = ((q31_t) * px++ * coeff); 
+    *pScratchOut++ = ((q31_t) * px++ * coeff); 
+    *pScratchOut++ = ((q31_t) * 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 multiplication and store in the scratch buffer */ 
+    *pScratchOut++ = ((q31_t) * 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 = (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_q15(py, delaySize, &readIndex, 1, 
+                         pb, pb, blockSize, 1, blockSize); 
+ 
+    /* Working pointer for the scratch buffer of state values */ 
+    px = pb; 
+ 
+    /* Working pointer for scratch buffer of output values */ 
+    pScratchOut = pScr2; 
+ 
+    /* Loop over the blockSize. Unroll by a factor of 4.  
+     * Compute 4 MACS at a time. */ 
+    blkCnt = blockSize >> 2; 
+ 
+    while(blkCnt > 0u) 
+    { 
+      /* Perform Multiply-Accumulate */ 
+      *pScratchOut++ += (q31_t) * px++ * coeff; 
+      *pScratchOut++ += (q31_t) * px++ * coeff; 
+      *pScratchOut++ += (q31_t) * px++ * coeff; 
+      *pScratchOut++ += (q31_t) * 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 */ 
+      *pScratchOut++ += (q31_t) * 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 = (S->stateIndex - blockSize) - *pTapDelay++; 
+ 
+    /* Wraparound of readIndex */ 
+    if(readIndex < 0) 
+    { 
+      readIndex += (int32_t) delaySize; 
+    } 
+ 
+    /* Decrement the tap loop counter */ 
+    tapCnt--; 
+  } 
+ 
+  /* All the output values are in pScratchOut buffer.  
+     Convert them into 1.15 format, saturate and store in the destination buffer. */ 
+  /* Loop over the blockSize. */ 
+  blkCnt = blockSize >> 2; 
+ 
+  while(blkCnt > 0u) 
+  { 
+    in1 = *pScr2++; 
+    in2 = *pScr2++; 
+    *__SIMD32(pOut)++ = 
+      __PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16), 
+              16); 
+ 
+    in1 = *pScr2++; 
+    in2 = *pScr2++; 
+    *__SIMD32(pOut)++ = 
+      __PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16), 
+              16); 
+ 
+    blkCnt--; 
+ 
+  } 
+ 
+  /* If the blockSize is not a multiple of 4,  
+     remaining samples are processed in the below loop */ 
+  blkCnt = blockSize % 0x4u; 
+ 
+  while(blkCnt > 0u) 
+  { 
+    *pOut++ = (q15_t) __SSAT(*pScr2++ >> 15, 16); 
+    blkCnt--; 
+  } 
+} 
+ 
+/**  
+ * @} end of FIR_Sparse group  
+ */