Diff: cmsis_dsp/FilteringFunctions/arm_lms_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_lms_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,364 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_lms_q31.c    
+*    
+* Description:    Processing function for the Q31 LMS filter.    
+*    
+* 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"
+/**    
+ * @ingroup groupFilters    
+ */
+
+/**    
+ * @addtogroup LMS    
+ * @{    
+ */
+
+ /**    
+ * @brief Processing function for Q31 LMS filter.    
+ * @param[in]  *S points to an instance of the Q15 LMS filter structure.    
+ * @param[in]  *pSrc points to the block of input data.    
+ * @param[in]  *pRef points to the block of reference data.    
+ * @param[out] *pOut points to the block of output data.    
+ * @param[out] *pErr points to the block of error data.    
+ * @param[in]  blockSize number of samples to process.    
+ * @return     none.    
+ *    
+ * \par Scaling and Overflow Behavior:     
+ * The function is implemented using an internal 64-bit accumulator.     
+ * The accumulator has a 2.62 format and maintains full precision of the intermediate    
+ * multiplication results but provides only a single guard bit.     
+ * Thus, if the accumulator result overflows it wraps around rather than clips.     
+ * In order to avoid overflows completely the input signal must be scaled down by    
+ * log2(numTaps) bits.     
+ * The reference signal should not be scaled down.     
+ * After all multiply-accumulates are performed, the 2.62 accumulator is shifted    
+ * and saturated to 1.31 format to yield the final result.     
+ * The output signal and error signal are in 1.31 format.     
+ *    
+ * \par    
+ *     In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.    
+ */
+
+void arm_lms_q31(
+  const arm_lms_instance_q31 * S,
+  q31_t * pSrc,
+  q31_t * pRef,
+  q31_t * pOut,
+  q31_t * pErr,
+  uint32_t blockSize)
+{
+  q31_t *pState = S->pState;                     /* State pointer */
+  uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
+  q31_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
+  q31_t *pStateCurnt;                            /* Points to the current sample of the state */
+  q31_t mu = S->mu;                              /* Adaptive factor */
+  q31_t *px;                                     /* Temporary pointer for state */
+  q31_t *pb;                                     /* Temporary pointer for coefficient buffer */
+  uint32_t tapCnt, blkCnt;                       /* Loop counters */
+  q63_t acc;                                     /* Accumulator */
+  q31_t e = 0;                                   /* error of data sample */
+  q31_t alpha;                                   /* Intermediate constant for taps update */
+  q31_t coef;                                    /* Temporary variable for coef */
+  q31_t acc_l, acc_h;                            /*  temporary input */
+  uint32_t uShift = ((uint32_t) S->postShift + 1u);
+  uint32_t lShift = 32u - uShift;                /*  Shift to be applied to the output */
+
+  /* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
+  /* pStateCurnt points to the location where the new input data should be written */
+  pStateCurnt = &(S->pState[(numTaps - 1u)]);
+
+  /* Initializing blkCnt with blockSize */
+  blkCnt = blockSize;
+
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+  while(blkCnt > 0u)
+  {
+    /* Copy the new input sample into the state buffer */
+    *pStateCurnt++ = *pSrc++;
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* Initialize coefficient pointer */
+    pb = pCoeffs;
+
+    /* Set the accumulator to zero */
+    acc = 0;
+
+    /* Loop unrolling.  Process 4 taps at a time. */
+    tapCnt = numTaps >> 2;
+
+    while(tapCnt > 0u)
+    {
+      /* Perform the multiply-accumulate */
+      /* acc +=  b[N] * x[n-N] */
+      acc += ((q63_t) (*px++)) * (*pb++);
+
+      /* acc +=  b[N-1] * x[n-N-1] */
+      acc += ((q63_t) (*px++)) * (*pb++);
+
+      /* acc +=  b[N-2] * x[n-N-2] */
+      acc += ((q63_t) (*px++)) * (*pb++);
+
+      /* acc +=  b[N-3] * x[n-N-3] */
+      acc += ((q63_t) (*px++)) * (*pb++);
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* If the filter length is not a multiple of 4, compute the remaining filter taps */
+    tapCnt = numTaps % 0x4u;
+
+    while(tapCnt > 0u)
+    {
+      /* Perform the multiply-accumulate */
+      acc += ((q63_t) (*px++)) * (*pb++);
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* Converting the result to 1.31 format */
+    /* Calc lower part of acc */
+    acc_l = acc & 0xffffffff;
+
+    /* Calc upper part of acc */
+    acc_h = (acc >> 32) & 0xffffffff;
+
+    acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
+
+    /* Store the result from accumulator into the destination buffer. */
+    *pOut++ = (q31_t) acc;
+
+    /* Compute and store error */
+    e = *pRef++ - (q31_t) acc;
+
+    *pErr++ = (q31_t) e;
+
+    /* Compute alpha i.e. intermediate constant for taps update */
+    alpha = (q31_t) (((q63_t) e * mu) >> 31);
+
+    /* Initialize state pointer */
+    /* Advance state pointer by 1 for the next sample */
+    px = pState++;
+
+    /* Initialize coefficient pointer */
+    pb = pCoeffs;
+
+    /* Loop unrolling.  Process 4 taps at a time. */
+    tapCnt = numTaps >> 2;
+
+    /* Update filter coefficients */
+    while(tapCnt > 0u)
+    {
+      /* coef is in 2.30 format */
+      coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
+      /* get coef in 1.31 format by left shifting */
+      *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
+      /* update coefficient buffer to next coefficient */
+      pb++;
+
+      coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
+      *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
+      pb++;
+
+      coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
+      *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
+      pb++;
+
+      coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
+      *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
+      pb++;
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* If the filter length is not a multiple of 4, compute the remaining filter taps */
+    tapCnt = numTaps % 0x4u;
+
+    while(tapCnt > 0u)
+    {
+      /* Perform the multiply-accumulate */
+      coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
+      *pb = clip_q63_to_q31((q63_t) * pb + (coef << 1u));
+      pb++;
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* Processing is complete. Now copy the last numTaps - 1 samples to the    
+     satrt of the state buffer. This prepares the state buffer for the    
+     next function call. */
+
+  /* Points to the start of the pState buffer */
+  pStateCurnt = S->pState;
+
+  /* Loop unrolling for (numTaps - 1u) samples copy */
+  tapCnt = (numTaps - 1u) >> 2u;
+
+  /* copy data */
+  while(tapCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+    *pStateCurnt++ = *pState++;
+    *pStateCurnt++ = *pState++;
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    tapCnt--;
+  }
+
+  /* Calculate remaining number of copies */
+  tapCnt = (numTaps - 1u) % 0x4u;
+
+  /* Copy the remaining q31_t data */
+  while(tapCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    tapCnt--;
+  }
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  while(blkCnt > 0u)
+  {
+    /* Copy the new input sample into the state buffer */
+    *pStateCurnt++ = *pSrc++;
+
+    /* Initialize pState pointer */
+    px = pState;
+
+    /* Initialize pCoeffs pointer */
+    pb = pCoeffs;
+
+    /* Set the accumulator to zero */
+    acc = 0;
+
+    /* Loop over numTaps number of values */
+    tapCnt = numTaps;
+
+    while(tapCnt > 0u)
+    {
+      /* Perform the multiply-accumulate */
+      acc += ((q63_t) (*px++)) * (*pb++);
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* Converting the result to 1.31 format */
+    /* Store the result from accumulator into the destination buffer. */
+    /* Calc lower part of acc */
+    acc_l = acc & 0xffffffff;
+
+    /* Calc upper part of acc */
+    acc_h = (acc >> 32) & 0xffffffff;
+
+    acc = (uint32_t) acc_l >> lShift | acc_h << uShift;
+
+    *pOut++ = (q31_t) acc;
+
+    /* Compute and store error */
+    e = *pRef++ - (q31_t) acc;
+
+    *pErr++ = (q31_t) e;
+
+    /* Weighting factor for the LMS version */
+    alpha = (q31_t) (((q63_t) e * mu) >> 31);
+
+    /* Initialize pState pointer */
+    /* Advance state pointer by 1 for the next sample */
+    px = pState++;
+
+    /* Initialize pCoeffs pointer */
+    pb = pCoeffs;
+
+    /* Loop over numTaps number of values */
+    tapCnt = numTaps;
+
+    while(tapCnt > 0u)
+    {
+      /* Perform the multiply-accumulate */
+      coef = (q31_t) (((q63_t) alpha * (*px++)) >> (32));
+      *pb += (coef << 1u);
+      pb++;
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* Processing is complete. Now copy the last numTaps - 1 samples to the     
+     start of the state buffer. This prepares the state buffer for the   
+     next function call. */
+
+  /* Points to the start of the pState buffer */
+  pStateCurnt = S->pState;
+
+  /*  Copy (numTaps - 1u) samples  */
+  tapCnt = (numTaps - 1u);
+
+  /* Copy the data */
+  while(tapCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    tapCnt--;
+  }
+
+#endif /*   #ifndef ARM_MATH_CM0 */
+
+}
+
+/**    
+   * @} end of LMS group    
+   */