Diff: FilteringFunctions/arm_fir_sparse_q15.c

Revision:

0:3d9c67d97d6f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FilteringFunctions/arm_fir_sparse_q15.c	Mon Jul 28 15:03:15 2014 +0000
@@ -0,0 +1,411 @@
+/* ----------------------------------------------------------------------    
+* 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_q15.c    
+*    
+* Description:	Q15 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"
+
+/**    
+ * @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 = 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 */
+
+
+#ifndef ARM_MATH_CM0_FAMILY
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+  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++;
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+    *__SIMD32(pOut)++ =
+      __PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16),
+              16);
+
+#else
+    *__SIMD32(pOut)++ =
+      __PKHBT((q15_t) __SSAT(in2 >> 15, 16), (q15_t) __SSAT(in1 >> 15, 16),
+              16);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+    in1 = *pScr2++;
+
+    in2 = *pScr2++;
+
+#ifndef  ARM_MATH_BIG_ENDIAN
+
+    *__SIMD32(pOut)++ =
+      __PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16),
+              16);
+
+#else
+
+    *__SIMD32(pOut)++ =
+      __PKHBT((q15_t) __SSAT(in2 >> 15, 16), (q15_t) __SSAT(in1 >> 15, 16),
+              16);
+
+#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */
+
+
+    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--;
+  }
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  /* 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;
+
+  blkCnt = blockSize;
+
+  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;
+
+    blkCnt = blockSize;
+
+    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;
+
+  while(blkCnt > 0u)
+  {
+    *pOut++ = (q15_t) __SSAT(*pScr2++ >> 15, 16);
+    blkCnt--;
+  }
+
+#endif /*   #ifndef ARM_MATH_CM0_FAMILY */
+
+}
+
+/**    
+ * @} end of FIR_Sparse group    
+ */