Diff: cmsis_dsp/FilteringFunctions/arm_fir_f32.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FilteringFunctions/arm_fir_f32.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,554 @@
+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*  
+* Project:         CMSIS DSP Library  
+* Title:        arm_fir_f32.c  
+*  
+* Description:    Floating-point FIR 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 1.0.2 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 0.0.5  2010/04/26   
+*      incorporated review comments and updated with latest CMSIS layer  
+*  
+* Version 0.0.3  2010/03/10   
+*    Initial version  
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**  
+ * @ingroup groupFilters  
+ */
+
+/**  
+ * @defgroup FIR Finite Impulse Response (FIR) Filters  
+ *  
+ * This set of functions implements Finite Impulse Response (FIR) filters  
+ * for Q7, Q15, Q31, and floating-point data types.  Fast versions of Q15 and Q31 are also provided.  
+ * 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> points to input and output arrays containing <code>blockSize</code> values.  
+ *  
+ * \par Algorithm:  
+ * The FIR filter algorithm is based upon a sequence of multiply-accumulate (MAC) operations.  
+ * Each filter coefficient <code>b[n]</code> is multiplied by a state variable which equals a previous input sample <code>x[n]</code>.  
+ * <pre>  
+ *    y[n] = b[0] * x[n] + b[1] * x[n-1] + b[2] * x[n-2] + ...+ b[numTaps-1] * x[n-numTaps+1]  
+ * </pre>  
+ * \par  
+ * \image html FIR.gif "Finite Impulse Response filter"  
+ * \par  
+ * <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>.  
+ * Coefficients are stored in time reversed order.  
+ * \par  
+ * <pre>  
+ *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}  
+ * </pre>  
+ * \par  
+ * <code>pState</code> points to a state array of size <code>numTaps + blockSize - 1</code>.  
+ * Samples in the state buffer are stored in the following order.  
+ * \par  
+ * <pre>  
+ *    {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}  
+ * </pre>  
+ * \par  
+ * Note that the length of the state buffer exceeds the length of the coefficient array by <code>blockSize-1</code>.  
+ * The increased state buffer length allows circular addressing, which is traditionally used in the FIR filters,  
+ * to be avoided and yields a significant speed improvement.  
+ * 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 4 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 before static initialization.  
+ * The code below statically initializes each of the 4 different data type filter instance structures  
+ * <pre>  
+ *arm_fir_instance_f32 S = {numTaps, pState, pCoeffs};  
+ *arm_fir_instance_q31 S = {numTaps, pState, pCoeffs};  
+ *arm_fir_instance_q15 S = {numTaps, pState, pCoeffs};  
+ *arm_fir_instance_q7 S =  {numTaps, pState, pCoeffs};  
+ * </pre>  
+ *  
+ * where <code>numTaps</code> is the number of filter coefficients in the filter; <code>pState</code> is the address of the state buffer;  
+ * <code>pCoeffs</code> is the address of the coefficient buffer.  
+ *  
+ * \par Fixed-Point Behavior  
+ * Care must be taken when using the fixed-point versions of the FIR 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 FIR  
+ * @{  
+ */
+
+/**  
+ *  
+ * @param[in]  *S points to an instance of the floating-point FIR filter 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 per call.  
+ * @return     none.  
+ *  
+ */
+
+#ifndef ARM_MATH_CM0
+
+  /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+void arm_fir_f32(
+  const arm_fir_instance_f32 * S,
+  float32_t * pSrc,
+  float32_t * pDst,
+  uint32_t blockSize)
+{
+  float32_t *pState = S->pState;                 /* State pointer */
+  float32_t *pCoeffs = S->pCoeffs;               /* Coefficient pointer */
+  float32_t *pStateCurnt;                        /* Points to the current sample of the state */
+  float32_t *px, *pb;                            /* Temporary pointers for state and coefficient buffers */
+  float32_t acc0, acc1, acc2, acc3, acc4, acc5, acc6, acc7;     /* Accumulators */
+  float32_t x0, x1, x2, x3, x4, x5, x6, x7, c0;  /* Temporary variables to hold state and coefficient values */
+  uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
+  uint32_t i, tapCnt, blkCnt;                    /* Loop counters */
+
+  /* S->pState points to state array 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)]);
+
+  /* Apply loop unrolling and compute 4 output values simultaneously.  
+   * The variables acc0 ... acc3 hold output values that are being computed:  
+   *  
+   *    acc0 =  b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]  
+   *    acc1 =  b[numTaps-1] * x[n-numTaps] +   b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]  
+   *    acc2 =  b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] +   b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]  
+   *    acc3 =  b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps]   +...+ b[0] * x[3]  
+   */
+  blkCnt = blockSize >> 3;
+
+  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
+   ** a second loop below computes the remaining 1 to 3 samples. */
+  while(blkCnt > 0u)
+  {
+    /* Copy four new input samples into the state buffer */
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+    *pStateCurnt++ = *pSrc++;
+
+    /* Set all accumulators to zero */
+    acc0 = 0.0f;
+    acc1 = 0.0f;
+    acc2 = 0.0f;
+    acc3 = 0.0f;
+    acc4 = 0.0f;
+    acc5 = 0.0f;
+    acc6 = 0.0f;
+    acc7 = 0.0f;
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* Initialize coeff pointer */
+    pb = (pCoeffs);
+
+    /* Read the first three samples from the state buffer:  x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */
+    x0 = *px++;
+    x1 = *px++;
+    x2 = *px++;
+    x3 = *px++;
+    x4 = *px++;
+    x5 = *px++;
+    x6 = *px++;
+
+    /* Loop unrolling.  Process 4 taps at a time. */
+    tapCnt = numTaps >> 3u;
+
+    /* Loop over the number of taps.  Unroll by a factor of 4.  
+     ** Repeat until we've computed numTaps-4 coefficients. */
+    while(tapCnt > 0u)
+    {
+      /* Read the b[numTaps-1] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-3] sample */
+      x7 = *(px++);
+
+      /* acc0 +=  b[numTaps-1] * x[n-numTaps] */
+      acc0 += x0 * c0;
+
+      /* acc1 +=  b[numTaps-1] * x[n-numTaps-1] */
+      acc1 += x1 * c0;
+
+      /* acc2 +=  b[numTaps-1] * x[n-numTaps-2] */
+      acc2 += x2 * c0;
+
+      /* acc3 +=  b[numTaps-1] * x[n-numTaps-3] */
+      acc3 += x3 * c0;
+
+      /* acc4 +=  b[numTaps-1] * x[n-numTaps-4] */
+      acc4 += x4 * c0;
+
+      /* acc1 +=  b[numTaps-1] * x[n-numTaps-5] */
+      acc5 += x5 * c0;
+
+      /* acc2 +=  b[numTaps-1] * x[n-numTaps-6] */
+      acc6 += x6 * c0;
+
+      /* acc3 +=  b[numTaps-1] * x[n-numTaps-7] */
+      acc7 += x7 * c0;
+
+      /* Read the b[numTaps-2] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-4] sample */
+      x0 = *(px++);
+
+      /* Perform the multiply-accumulate */
+      acc0 += x1 * c0;
+      acc1 += x2 * c0;
+      acc2 += x3 * c0;
+      acc3 += x4 * c0;
+      acc4 += x5 * c0;
+      acc5 += x6 * c0;
+      acc6 += x7 * c0;
+      acc7 += x0 * c0;
+
+      /* Read the b[numTaps-3] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-5] sample */
+      x1 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x2 * c0;
+      acc1 += x3 * c0;
+      acc2 += x4 * c0;
+      acc3 += x5 * c0;
+      acc4 += x6 * c0;
+      acc5 += x7 * c0;
+      acc6 += x0 * c0;
+      acc7 += x1 * c0;
+
+      /* Read the b[numTaps-4] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-6] sample */
+      x2 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x3 * c0;
+      acc1 += x4 * c0;
+      acc2 += x5 * c0;
+      acc3 += x6 * c0;
+      acc4 += x7 * c0;
+      acc5 += x0 * c0;
+      acc6 += x1 * c0;
+      acc7 += x2 * c0;
+
+      /* Read the b[numTaps-4] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-6] sample */
+      x3 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x4 * c0;
+      acc1 += x5 * c0;
+      acc2 += x6 * c0;
+      acc3 += x7 * c0;
+      acc4 += x0 * c0;
+      acc5 += x1 * c0;
+      acc6 += x2 * c0;
+      acc7 += x3 * c0;
+
+      /* Read the b[numTaps-4] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-6] sample */
+      x4 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x5 * c0;
+      acc1 += x6 * c0;
+      acc2 += x7 * c0;
+      acc3 += x0 * c0;
+      acc4 += x1 * c0;
+      acc5 += x2 * c0;
+      acc6 += x3 * c0;
+      acc7 += x4 * c0;
+
+      /* Read the b[numTaps-4] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-6] sample */
+      x5 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x6 * c0;
+      acc1 += x7 * c0;
+      acc2 += x0 * c0;
+      acc3 += x1 * c0;
+      acc4 += x2 * c0;
+      acc5 += x3 * c0;
+      acc6 += x4 * c0;
+      acc7 += x5 * c0;
+
+      /* Read the b[numTaps-4] coefficient */
+      c0 = *(pb++);
+
+      /* Read x[n-numTaps-6] sample */
+      x6 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x7 * c0;
+      acc1 += x0 * c0;
+      acc2 += x1 * c0;
+      acc3 += x2 * c0;
+      acc4 += x3 * c0;
+      acc5 += x4 * c0;
+      acc6 += x5 * c0;
+      acc7 += x6 * c0;
+
+      tapCnt--;
+    }
+
+    /* If the filter length is not a multiple of 4, compute the remaining filter taps */
+    tapCnt = numTaps % 0x8u;
+
+    while(tapCnt > 0u)
+    {
+      /* Read coefficients */
+      c0 = *(pb++);
+
+      /* Fetch 1 state variable */
+      x7 = *(px++);
+
+      /* Perform the multiply-accumulates */
+      acc0 += x0 * c0;
+      acc1 += x1 * c0;
+      acc2 += x2 * c0;
+      acc3 += x3 * c0;
+      acc4 += x4 * c0;
+      acc5 += x5 * c0;
+      acc6 += x6 * c0;
+      acc7 += x7 * c0;
+
+      /* Reuse the present sample states for next sample */
+      x0 = x1;
+      x1 = x2;
+      x2 = x3;
+      x3 = x4;
+      x4 = x5;
+      x5 = x6;
+      x6 = x7;
+
+      /* Decrement the loop counter */
+      tapCnt--;
+    }
+
+    /* Advance the state pointer by 4 to process the next group of 4 samples */
+    pState = pState + 8;
+
+    /* The results in the 4 accumulators, store in the destination buffer. */
+    *pDst++ = acc0;
+    *pDst++ = acc1;
+    *pDst++ = acc2;
+    *pDst++ = acc3;
+    *pDst++ = acc4;
+    *pDst++ = acc5;
+    *pDst++ = acc6;
+    *pDst++ = acc7;
+
+    blkCnt--;
+  }
+
+  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.  
+   ** No loop unrolling is used. */
+  blkCnt = blockSize % 0x8u;
+
+  while(blkCnt > 0u)
+  {
+    /* Copy one sample at a time into state buffer */
+    *pStateCurnt++ = *pSrc++;
+
+    /* Set the accumulator to zero */
+    acc0 = 0.0f;
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* Initialize Coefficient pointer */
+    pb = (pCoeffs);
+
+    i = numTaps;
+
+    /* Perform the multiply-accumulates */
+    do
+    {
+      acc0 += *px++ * *pb++;
+      i--;
+
+    } while(i > 0u);
+
+    /* The result is store in the destination buffer. */
+    *pDst++ = acc0;
+
+    /* Advance state pointer by 1 for the next sample */
+    pState = pState + 1;
+
+    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 state buffer */
+  pStateCurnt = S->pState;
+
+  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
+
+void arm_fir_f32(
+  const arm_fir_instance_f32 * S,
+  float32_t * pSrc,
+  float32_t * pDst,
+  uint32_t blockSize)
+{
+  float32_t *pState = S->pState;                 /* State pointer */
+  float32_t *pCoeffs = S->pCoeffs;               /* Coefficient pointer */
+  float32_t *pStateCurnt;                        /* Points to the current sample of the state */
+  float32_t *px, *pb;                            /* Temporary pointers for state and coefficient buffers */
+  uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
+  uint32_t i, tapCnt, blkCnt;                    /* Loop counters */
+
+  /* Run the below code for Cortex-M0 */
+
+  float32_t acc;
+
+  /* S->pState points to state array 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)]);
+
+  /* Initialize blkCnt with blockSize */
+  blkCnt = blockSize;
+
+  while(blkCnt > 0u)
+  {
+    /* Copy one sample at a time into state buffer */
+    *pStateCurnt++ = *pSrc++;
+
+    /* Set the accumulator to zero */
+    acc = 0.0f;
+
+    /* Initialize state pointer */
+    px = pState;
+
+    /* Initialize Coefficient pointer */
+    pb = pCoeffs;
+
+    i = numTaps;
+
+    /* Perform the multiply-accumulates */
+    do
+    {
+      /* acc =  b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0] */
+      acc += *px++ * *pb++;
+      i--;
+
+    } while(i > 0u);
+
+    /* The result is store in the destination buffer. */
+    *pDst++ = acc;
+
+    /* Advance state pointer by 1 for the next sample */
+    pState = pState + 1;
+
+    blkCnt--;
+  }
+
+  /* Processing is complete.         
+   ** Now copy the last numTaps - 1 samples to the starting of the state buffer.       
+   ** This prepares the state buffer for the next function call. */
+
+  /* Points to the start of the state buffer */
+  pStateCurnt = S->pState;
+
+  /* Copy numTaps number of values */
+  tapCnt = numTaps - 1u;
+
+  /* Copy data */
+  while(tapCnt > 0u)
+  {
+    *pStateCurnt++ = *pState++;
+
+    /* Decrement the loop counter */
+    tapCnt--;
+  }
+
+}
+
+#endif /*   #ifndef ARM_MATH_CM0 */
+
+/**  
+ * @} end of FIR group  
+ */