Diff: cmsis_dsp/FilteringFunctions/arm_iir_lattice_f32.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_iir_lattice_f32.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,440 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_iir_lattice_f32.c    
+*    
+* Description:    Floating-point IIR 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    
+ */
+
+/**    
+ * @defgroup IIR_Lattice Infinite Impulse Response (IIR) Lattice Filters    
+ *    
+ * This set of functions implements lattice filters    
+ * for Q15, Q31 and floating-point data types.  Lattice filters are used in a     
+ * variety of adaptive filter applications.  The filter structure has feedforward and    
+ * feedback components and the net impulse response is infinite length.    
+ * 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> point to input and output arrays containing <code>blockSize</code> values.    
+    
+ * \par Algorithm:    
+ * \image html IIRLattice.gif "Infinite Impulse Response Lattice filter"    
+ * <pre>    
+ *    fN(n)   =  x(n)    
+ *    fm-1(n) = fm(n) - km * gm-1(n-1)   for m = N, N-1, ...1    
+ *    gm(n)   = km * fm-1(n) + gm-1(n-1) for m = N, N-1, ...1    
+ *    y(n)    = vN * gN(n) + vN-1 * gN-1(n) + ...+ v0 * g0(n)    
+ * </pre>    
+ * \par    
+ * <code>pkCoeffs</code> points to array of reflection coefficients of size <code>numStages</code>.     
+ * Reflection coefficients are stored in time-reversed order.    
+ * \par    
+ * <pre>    
+ *    {kN, kN-1, ....k1}    
+ * </pre>    
+ * <code>pvCoeffs</code> points to the array of ladder coefficients of size <code>(numStages+1)</code>.     
+ * Ladder coefficients are stored in time-reversed order.    
+ * \par    
+ * <pre>    
+ *    {vN, vN-1, ...v0}    
+ * </pre>    
+ * <code>pState</code> points to a state array of size <code>numStages + blockSize</code>.    
+ * The state variables shown in the figure above (the g values) are stored in the <code>pState</code> array.    
+ * The state variables are updated after each block of data is processed; the coefficients are untouched.    
+ * \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 arrays may be shared among several instances while state variable arrays cannot be shared.    
+ * There are separate instance structure declarations for each of the 3 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 and then manually initialize the instance structure as follows:    
+ * <pre>    
+ *arm_iir_lattice_instance_f32 S = {numStages, pState, pkCoeffs, pvCoeffs};    
+ *arm_iir_lattice_instance_q31 S = {numStages, pState, pkCoeffs, pvCoeffs};    
+ *arm_iir_lattice_instance_q15 S = {numStages, pState, pkCoeffs, pvCoeffs};    
+ * </pre>    
+ * \par    
+ * where <code>numStages</code> is the number of stages in the filter; <code>pState</code> points to the state buffer array;    
+ * <code>pkCoeffs</code> points to array of the reflection coefficients; <code>pvCoeffs</code> points to the array of ladder coefficients.    
+ * \par Fixed-Point Behavior    
+ * Care must be taken when using the fixed-point versions of the IIR lattice 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 IIR_Lattice    
+ * @{    
+ */
+
+/**    
+ * @brief Processing function for the floating-point IIR lattice filter.    
+ * @param[in] *S points to an instance of the floating-point IIR 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.    
+ */
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+void arm_iir_lattice_f32(
+  const arm_iir_lattice_instance_f32 * S,
+  float32_t * pSrc,
+  float32_t * pDst,
+  uint32_t blockSize)
+{
+  float32_t fnext1, gcurr1, gnext;               /* Temporary variables for lattice stages */
+  float32_t acc;                                 /* Accumlator */
+  uint32_t blkCnt, tapCnt;                       /* temporary variables for counts */
+  float32_t *px1, *px2, *pk, *pv;                /* temporary pointers for state and coef */
+  uint32_t numStages = S->numStages;             /* number of stages */
+  float32_t *pState;                             /* State pointer */
+  float32_t *pStateCurnt;                        /* State current pointer */
+  float32_t k1, k2;
+  float32_t v1, v2, v3, v4;
+  float32_t gcurr2;
+  float32_t fnext2;
+
+  /* initialise loop count */
+  blkCnt = blockSize;
+
+  /* initialise state pointer */
+  pState = &S->pState[0];
+
+  /* Sample processing */
+  while(blkCnt > 0u)
+  {
+    /* Read Sample from input buffer */
+    /* fN(n) = x(n) */
+    fnext2 = *pSrc++;
+
+    /* Initialize Ladder coeff pointer */
+    pv = &S->pvCoeffs[0];
+    /* Initialize Reflection coeff pointer */
+    pk = &S->pkCoeffs[0];
+
+    /* Initialize state read pointer */
+    px1 = pState;
+    /* Initialize state write pointer */
+    px2 = pState;
+
+    /* Set accumulator to zero */
+    acc = 0.0;
+
+    /* Loop unrolling.  Process 4 taps at a time. */
+    tapCnt = (numStages) >> 2;
+
+    while(tapCnt > 0u)
+    {
+      /* Read gN-1(n-1) from state buffer */
+      gcurr1 = *px1;
+
+      /* read reflection coefficient kN */
+      k1 = *pk;
+
+      /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
+      fnext1 = fnext2 - (k1 * gcurr1);
+
+      /* read ladder coefficient vN */
+      v1 = *pv;
+
+      /* read next reflection coefficient kN-1 */
+      k2 = *(pk + 1u);
+
+      /* Read gN-2(n-1) from state buffer */
+      gcurr2 = *(px1 + 1u);
+
+      /* read next ladder coefficient vN-1 */
+      v2 = *(pv + 1u);
+
+      /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
+      fnext2 = fnext1 - (k2 * gcurr2);
+
+      /* gN(n)   = kN * fN-1(n) + gN-1(n-1) */
+      gnext = gcurr1 + (k1 * fnext1);
+
+      /* read reflection coefficient kN-2 */
+      k1 = *(pk + 2u);
+
+      /* write gN(n) into state for next sample processing */
+      *px2++ = gnext;
+
+      /* Read gN-3(n-1) from state buffer */
+      gcurr1 = *(px1 + 2u);
+
+      /* y(n) += gN(n) * vN  */
+      acc += (gnext * v1);
+
+      /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
+      fnext1 = fnext2 - (k1 * gcurr1);
+
+      /* gN-1(n)   = kN-1 * fN-2(n) + gN-2(n-1) */
+      gnext = gcurr2 + (k2 * fnext2);
+
+      /* Read gN-4(n-1) from state buffer */
+      gcurr2 = *(px1 + 3u);
+
+      /* y(n) += gN-1(n) * vN-1  */
+      acc += (gnext * v2);
+
+      /* read reflection coefficient kN-3 */
+      k2 = *(pk + 3u);
+
+      /* write gN-1(n) into state for next sample processing */
+      *px2++ = gnext;
+
+      /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
+      fnext2 = fnext1 - (k2 * gcurr2);
+
+      /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
+      gnext = gcurr1 + (k1 * fnext1);
+
+      /* read ladder coefficient vN-2 */
+      v3 = *(pv + 2u);
+
+      /* y(n) += gN-2(n) * vN-2  */
+      acc += (gnext * v3);
+
+      /* write gN-2(n) into state for next sample processing */
+      *px2++ = gnext;
+
+      /* update pointer */
+      pk += 4u;
+
+      /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
+      gnext = (fnext2 * k2) + gcurr2;
+
+      /* read next ladder coefficient vN-3 */
+      v4 = *(pv + 3u);
+
+      /* y(n) += gN-4(n) * vN-4  */
+      acc += (gnext * v4);
+
+      /* write gN-3(n) into state for next sample processing */
+      *px2++ = gnext;
+
+      /* update pointers */
+      px1 += 4u;
+      pv += 4u;
+
+      tapCnt--;
+
+    }
+
+    /* If the filter length is not a multiple of 4, compute the remaining filter taps */
+    tapCnt = (numStages) % 0x4u;
+
+    while(tapCnt > 0u)
+    {
+      gcurr1 = *px1++;
+      /* Process sample for last taps */
+      fnext1 = fnext2 - ((*pk) * gcurr1);
+      gnext = (fnext1 * (*pk++)) + gcurr1;
+      /* Output samples for last taps */
+      acc += (gnext * (*pv++));
+      *px2++ = gnext;
+      fnext2 = fnext1;
+
+      tapCnt--;
+
+    }
+
+    /* y(n) += g0(n) * v0 */
+    acc += (fnext2 * (*pv));
+
+    *px2++ = fnext2;
+
+    /* write out into pDst */
+    *pDst++ = acc;
+
+    /* Advance the state pointer by 4 to process the next group of 4 samples */
+    pState = pState + 1u;
+
+    blkCnt--;
+
+  }
+
+  /* Processing is complete. Now copy last S->numStages samples to start of the buffer        
+     for the preperation of next frame process */
+
+  /* Points to the start of the state buffer */
+  pStateCurnt = &S->pState[0];
+  pState = &S->pState[blockSize];
+
+  tapCnt = numStages >> 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 = (numStages) % 0x4u;
+
+  /* Copy the remaining q31_t data */
+  while(tapCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    tapCnt--;
+  }
+}
+
+#else
+
+void arm_iir_lattice_f32(
+  const arm_iir_lattice_instance_f32 * S,
+  float32_t * pSrc,
+  float32_t * pDst,
+  uint32_t blockSize)
+{
+  float32_t fcurr, fnext = 0, gcurr, gnext;      /* Temporary variables for lattice stages */
+  float32_t acc;                                 /* Accumlator */
+  uint32_t blkCnt, tapCnt;                       /* temporary variables for counts */
+  float32_t *px1, *px2, *pk, *pv;                /* temporary pointers for state and coef */
+  uint32_t numStages = S->numStages;             /* number of stages */
+  float32_t *pState;                             /* State pointer */
+  float32_t *pStateCurnt;                        /* State current pointer */
+
+
+  /* Run the below code for Cortex-M0 */
+
+  blkCnt = blockSize;
+
+  pState = &S->pState[0];
+
+  /* Sample processing */
+  while(blkCnt > 0u)
+  {
+    /* Read Sample from input buffer */
+    /* fN(n) = x(n) */
+    fcurr = *pSrc++;
+
+    /* Initialize state read pointer */
+    px1 = pState;
+    /* Initialize state write pointer */
+    px2 = pState;
+    /* Set accumulator to zero */
+    acc = 0.0f;
+    /* Initialize Ladder coeff pointer */
+    pv = &S->pvCoeffs[0];
+    /* Initialize Reflection coeff pointer */
+    pk = &S->pkCoeffs[0];
+
+
+    /* Process sample for numStages */
+    tapCnt = numStages;
+
+    while(tapCnt > 0u)
+    {
+      gcurr = *px1++;
+      /* Process sample for last taps */
+      fnext = fcurr - ((*pk) * gcurr);
+      gnext = (fnext * (*pk++)) + gcurr;
+
+      /* Output samples for last taps */
+      acc += (gnext * (*pv++));
+      *px2++ = gnext;
+      fcurr = fnext;
+
+      /* Decrementing loop counter */
+      tapCnt--;
+
+    }
+
+    /* y(n) += g0(n) * v0 */
+    acc += (fnext * (*pv));
+
+    *px2++ = fnext;
+
+    /* write out into pDst */
+    *pDst++ = acc;
+
+    /* Advance the state pointer by 1 to process the next group of samples */
+    pState = pState + 1u;
+    blkCnt--;
+
+  }
+
+  /* Processing is complete. Now copy last S->numStages samples to start of the buffer           
+     for the preperation of next frame process */
+
+  /* Points to the start of the state buffer */
+  pStateCurnt = &S->pState[0];
+  pState = &S->pState[blockSize];
+
+  tapCnt = numStages;
+
+  /* Copy the data */
+  while(tapCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    tapCnt--;
+  }
+
+}
+
+#endif /*   #ifndef ARM_MATH_CM0 */
+
+
+/**    
+ * @} end of IIR_Lattice group    
+ */