Diff: cmsis_dsp/FilteringFunctions/arm_fir_lattice_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_fir_lattice_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,348 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_fir_lattice_q31.c    
+*    
+* Description:    Q31 FIR lattice filter processing function.    
+*    
+* 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 FIR_Lattice    
+ * @{    
+ */
+
+
+/**    
+ * @brief Processing function for the Q31 FIR lattice filter.    
+ * @param[in]  *S        points to an instance of the Q31 FIR lattice structure.    
+ * @param[in]  *pSrc     points to the block of input data.    
+ * @param[out] *pDst     points to the block of output data    
+ * @param[in]  blockSize number of samples to process.    
+ * @return none.    
+ *    
+ * @details    
+ * <b>Scaling and Overflow Behavior:</b>    
+ * In order to avoid overflows the input signal must be scaled down by 2*log2(numStages) bits.    
+ */
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+void arm_fir_lattice_q31(
+  const arm_fir_lattice_instance_q31 * S,
+  q31_t * pSrc,
+  q31_t * pDst,
+  uint32_t blockSize)
+{
+  q31_t *pState;                                 /* State pointer */
+  q31_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
+  q31_t *px;                                     /* temporary state pointer */
+  q31_t *pk;                                     /* temporary coefficient pointer */
+  q31_t fcurr1, fnext1, gcurr1 = 0, gnext1;      /* temporary variables for first sample in loop unrolling */
+  q31_t fcurr2, fnext2, gnext2;                  /* temporary variables for second sample in loop unrolling */
+  uint32_t numStages = S->numStages;             /* Length of the filter */
+  uint32_t blkCnt, stageCnt;                     /* temporary variables for counts */
+  q31_t k;
+
+  pState = &S->pState[0];
+
+  blkCnt = blockSize >> 1u;
+
+  /* First part of the processing with loop unrolling.  Compute 2 outputs at a time.        
+     a second loop below computes the remaining 1 sample. */
+  while(blkCnt > 0u)
+  {
+    /* f0(n) = x(n) */
+    fcurr1 = *pSrc++;
+
+    /* f0(n) = x(n) */
+    fcurr2 = *pSrc++;
+
+    /* Initialize coeff pointer */
+    pk = (pCoeffs);
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* read g0(n - 1) from state buffer */
+    gcurr1 = *px;
+
+    /* Read the reflection coefficient */
+    k = *pk++;
+
+    /* for sample 1 processing */
+    /* f1(n) = f0(n) +  K1 * g0(n-1) */
+    fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
+
+    /* g1(n) = f0(n) * K1  +  g0(n-1) */
+    gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
+    fnext1 = fcurr1 + (fnext1 << 1u);
+    gnext1 = gcurr1 + (gnext1 << 1u);
+
+    /* for sample 1 processing */
+    /* f1(n) = f0(n) +  K1 * g0(n-1) */
+    fnext2 = (q31_t) (((q63_t) fcurr1 * k) >> 32);
+
+    /* g1(n) = f0(n) * K1  +  g0(n-1) */
+    gnext2 = (q31_t) (((q63_t) fcurr2 * (k)) >> 32);
+    fnext2 = fcurr2 + (fnext2 << 1u);
+    gnext2 = fcurr1 + (gnext2 << 1u);
+
+    /* save g1(n) in state buffer */
+    *px++ = fcurr2;
+
+    /* f1(n) is saved in fcurr1        
+       for next stage processing */
+    fcurr1 = fnext1;
+    fcurr2 = fnext2;
+
+    stageCnt = (numStages - 1u);
+
+    /* stage loop */
+    while(stageCnt > 0u)
+    {
+
+      /* Read the reflection coefficient */
+      k = *pk++;
+
+      /* read g2(n) from state buffer */
+      gcurr1 = *px;
+
+      /* save g1(n) in state buffer */
+      *px++ = gnext2;
+
+      /* Sample processing for K2, K3.... */
+      /* f2(n) = f1(n) +  K2 * g1(n-1) */
+      fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
+      fnext2 = (q31_t) (((q63_t) gnext1 * k) >> 32);
+
+      fnext1 = fcurr1 + (fnext1 << 1u);
+      fnext2 = fcurr2 + (fnext2 << 1u);
+
+      /* g2(n) = f1(n) * K2  +  g1(n-1) */
+      gnext2 = (q31_t) (((q63_t) fcurr2 * (k)) >> 32);
+      gnext2 = gnext1 + (gnext2 << 1u);
+
+      /* g2(n) = f1(n) * K2  +  g1(n-1) */
+      gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
+      gnext1 = gcurr1 + (gnext1 << 1u);
+
+      /* f1(n) is saved in fcurr1        
+         for next stage processing */
+      fcurr1 = fnext1;
+      fcurr2 = fnext2;
+
+      stageCnt--;
+
+    }
+
+    /* y(n) = fN(n) */
+    *pDst++ = fcurr1;
+    *pDst++ = fcurr2;
+
+    blkCnt--;
+
+  }
+
+  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.        
+   ** No loop unrolling is used. */
+  blkCnt = blockSize % 0x2u;
+
+  while(blkCnt > 0u)
+  {
+    /* f0(n) = x(n) */
+    fcurr1 = *pSrc++;
+
+    /* Initialize coeff pointer */
+    pk = (pCoeffs);
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* read g0(n - 1) from state buffer */
+    gcurr1 = *px;
+
+    /* Read the reflection coefficient */
+    k = *pk++;
+
+    /* for sample 1 processing */
+    /* f1(n) = f0(n) +  K1 * g0(n-1) */
+    fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
+    fnext1 = fcurr1 + (fnext1 << 1u);
+
+    /* g1(n) = f0(n) * K1  +  g0(n-1) */
+    gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
+    gnext1 = gcurr1 + (gnext1 << 1u);
+
+    /* save g1(n) in state buffer */
+    *px++ = fcurr1;
+
+    /* f1(n) is saved in fcurr1        
+       for next stage processing */
+    fcurr1 = fnext1;
+
+    stageCnt = (numStages - 1u);
+
+    /* stage loop */
+    while(stageCnt > 0u)
+    {
+      /* Read the reflection coefficient */
+      k = *pk++;
+
+      /* read g2(n) from state buffer */
+      gcurr1 = *px;
+
+      /* save g1(n) in state buffer */
+      *px++ = gnext1;
+
+      /* Sample processing for K2, K3.... */
+      /* f2(n) = f1(n) +  K2 * g1(n-1) */
+      fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
+      fnext1 = fcurr1 + (fnext1 << 1u);
+
+      /* g2(n) = f1(n) * K2  +  g1(n-1) */
+      gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
+      gnext1 = gcurr1 + (gnext1 << 1u);
+
+      /* f1(n) is saved in fcurr1        
+         for next stage processing */
+      fcurr1 = fnext1;
+
+      stageCnt--;
+
+    }
+
+
+    /* y(n) = fN(n) */
+    *pDst++ = fcurr1;
+
+    blkCnt--;
+
+  }
+
+
+}
+
+
+#else
+
+/* Run the below code for Cortex-M0 */
+
+void arm_fir_lattice_q31(
+  const arm_fir_lattice_instance_q31 * S,
+  q31_t * pSrc,
+  q31_t * pDst,
+  uint32_t blockSize)
+{
+  q31_t *pState;                                 /* State pointer */
+  q31_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
+  q31_t *px;                                     /* temporary state pointer */
+  q31_t *pk;                                     /* temporary coefficient pointer */
+  q31_t fcurr, fnext, gcurr, gnext;              /* temporary variables */
+  uint32_t numStages = S->numStages;             /* Length of the filter */
+  uint32_t blkCnt, stageCnt;                     /* temporary variables for counts */
+
+  pState = &S->pState[0];
+
+  blkCnt = blockSize;
+
+  while(blkCnt > 0u)
+  {
+    /* f0(n) = x(n) */
+    fcurr = *pSrc++;
+
+    /* Initialize coeff pointer */
+    pk = (pCoeffs);
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* read g0(n-1) from state buffer */
+    gcurr = *px;
+
+    /* for sample 1 processing */
+    /* f1(n) = f0(n) +  K1 * g0(n-1) */
+    fnext = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr;
+    /* g1(n) = f0(n) * K1  +  g0(n-1) */
+    gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr;
+    /* save g1(n) in state buffer */
+    *px++ = fcurr;
+
+    /* f1(n) is saved in fcurr1            
+       for next stage processing */
+    fcurr = fnext;
+
+    stageCnt = (numStages - 1u);
+
+    /* stage loop */
+    while(stageCnt > 0u)
+    {
+      /* read g2(n) from state buffer */
+      gcurr = *px;
+
+      /* save g1(n) in state buffer */
+      *px++ = gnext;
+
+      /* Sample processing for K2, K3.... */
+      /* f2(n) = f1(n) +  K2 * g1(n-1) */
+      fnext = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr;
+      /* g2(n) = f1(n) * K2  +  g1(n-1) */
+      gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr;
+
+      /* f1(n) is saved in fcurr1            
+         for next stage processing */
+      fcurr = fnext;
+
+      stageCnt--;
+
+    }
+
+    /* y(n) = fN(n) */
+    *pDst++ = fcurr;
+
+    blkCnt--;
+
+  }
+
+}
+
+#endif /*   #ifndef ARM_MATH_CM0 */
+
+
+/**    
+ * @} end of FIR_Lattice group    
+ */