arm_fir_lattice_f32.c
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r71 | /* ---------------------------------------------------------------------- | |||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 15. July 2011 | ||||
* $Revision: V1.0.10 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_fir_lattice_f32.c | ||||
* | ||||
* Description: Processing function for the floating-point FIR Lattice filter. | ||||
* | ||||
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | ||||
* | ||||
* 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 FIR_Lattice Finite Impulse Response (FIR) Lattice Filters | ||||
* | ||||
* This set of functions implements Finite Impulse Response (FIR) lattice filters | ||||
* for Q15, Q31 and floating-point data types. Lattice filters are used in a | ||||
* variety of adaptive filter applications. The filter structure is feedforward and | ||||
* the net impulse response is finite 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 FIRLattice.gif "Finite Impulse Response Lattice filter" | ||||
* The following difference equation is implemented: | ||||
* <pre> | ||||
* f0[n] = g0[n] = x[n] | ||||
* fm[n] = fm-1[n] + km * gm-1[n-1] for m = 1, 2, ...M | ||||
* gm[n] = km * fm-1[n] + gm-1[n-1] for m = 1, 2, ...M | ||||
* y[n] = fM[n] | ||||
* </pre> | ||||
* \par | ||||
* <code>pCoeffs</code> points to tha array of reflection coefficients of size <code>numStages</code>. | ||||
* Reflection Coefficients are stored in the following order. | ||||
* \par | ||||
* <pre> | ||||
* {k1, k2, ..., kM} | ||||
* </pre> | ||||
* where M is number of stages | ||||
* \par | ||||
* <code>pState</code> points to a state array of size <code>numStages</code>. | ||||
* The state variables (g values) hold previous inputs and are stored in the following order. | ||||
* <pre> | ||||
* {g0[n], g1[n], g2[n] ...gM-1[n]} | ||||
* </pre> | ||||
* 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_fir_lattice_instance_f32 S = {numStages, pState, pCoeffs}; | ||||
*arm_fir_lattice_instance_q31 S = {numStages, pState, pCoeffs}; | ||||
*arm_fir_lattice_instance_q15 S = {numStages, pState, pCoeffs}; | ||||
* </pre> | ||||
* \par | ||||
* where <code>numStages</code> is the number of stages 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 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 FIR_Lattice | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Processing function for the floating-point FIR lattice filter. | ||||
* @param[in] *S points to an instance of the floating-point 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. | ||||
*/ | ||||
void arm_fir_lattice_f32( | ||||
const arm_fir_lattice_instance_f32 * S, | ||||
float32_t * pSrc, | ||||
float32_t * pDst, | ||||
uint32_t blockSize) | ||||
{ | ||||
float32_t *pState; /* State pointer */ | ||||
float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ | ||||
float32_t *px; /* temporary state pointer */ | ||||
float32_t *pk; /* temporary coefficient pointer */ | ||||
#ifndef ARM_MATH_CM0 | ||||
/* Run the below code for Cortex-M4 and Cortex-M3 */ | ||||
float32_t fcurr1, fnext1, gcurr1, gnext1; /* temporary variables for first sample in loop unrolling */ | ||||
float32_t fcurr2, fnext2, gnext2; /* temporary variables for second sample in loop unrolling */ | ||||
float32_t fcurr3, fnext3, gnext3; /* temporary variables for third sample in loop unrolling */ | ||||
float32_t fcurr4, fnext4, gnext4; /* temporary variables for fourth sample in loop unrolling */ | ||||
uint32_t numStages = S->numStages; /* Number of stages in the filter */ | ||||
uint32_t blkCnt, stageCnt; /* temporary variables for counts */ | ||||
gcurr1 = 0.0f; | ||||
pState = &S->pState[0]; | ||||
blkCnt = blockSize >> 2; | ||||
/* 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) | ||||
{ | ||||
/* Read two samples from input buffer */ | ||||
/* f0(n) = x(n) */ | ||||
fcurr1 = *pSrc++; | ||||
fcurr2 = *pSrc++; | ||||
/* Initialize coeff pointer */ | ||||
pk = (pCoeffs); | ||||
/* Initialize state pointer */ | ||||
px = pState; | ||||
/* Read g0(n-1) from state */ | ||||
gcurr1 = *px; | ||||
/* Process first sample for first tap */ | ||||
/* f1(n) = f0(n) + K1 * g0(n-1) */ | ||||
fnext1 = fcurr1 + ((*pk) * gcurr1); | ||||
/* g1(n) = f0(n) * K1 + g0(n-1) */ | ||||
gnext1 = (fcurr1 * (*pk)) + gcurr1; | ||||
/* Process second sample for first tap */ | ||||
/* for sample 2 processing */ | ||||
fnext2 = fcurr2 + ((*pk) * fcurr1); | ||||
gnext2 = (fcurr2 * (*pk)) + fcurr1; | ||||
/* Read next two samples from input buffer */ | ||||
/* f0(n+2) = x(n+2) */ | ||||
fcurr3 = *pSrc++; | ||||
fcurr4 = *pSrc++; | ||||
/* Copy only last input samples into the state buffer | ||||
which will be used for next four samples processing */ | ||||
*px++ = fcurr4; | ||||
/* Process third sample for first tap */ | ||||
fnext3 = fcurr3 + ((*pk) * fcurr2); | ||||
gnext3 = (fcurr3 * (*pk)) + fcurr2; | ||||
/* Process fourth sample for first tap */ | ||||
fnext4 = fcurr4 + ((*pk) * fcurr3); | ||||
gnext4 = (fcurr4 * (*pk++)) + fcurr3; | ||||
/* Update of f values for next coefficient set processing */ | ||||
fcurr1 = fnext1; | ||||
fcurr2 = fnext2; | ||||
fcurr3 = fnext3; | ||||
fcurr4 = fnext4; | ||||
/* Loop unrolling. Process 4 taps at a time . */ | ||||
stageCnt = (numStages - 1u) >> 2u; | ||||
/* Loop over the number of taps. Unroll by a factor of 4. | ||||
** Repeat until we've computed numStages-3 coefficients. */ | ||||
/* Process 2nd, 3rd, 4th and 5th taps ... here */ | ||||
while(stageCnt > 0u) | ||||
{ | ||||
/* Read g1(n-1), g3(n-1) .... from state */ | ||||
gcurr1 = *px; | ||||
/* save g1(n) in state buffer */ | ||||
*px++ = gnext4; | ||||
/* Process first sample for 2nd, 6th .. tap */ | ||||
/* Sample processing for K2, K6.... */ | ||||
/* f2(n) = f1(n) + K2 * g1(n-1) */ | ||||
fnext1 = fcurr1 + ((*pk) * gcurr1); | ||||
/* Process second sample for 2nd, 6th .. tap */ | ||||
/* for sample 2 processing */ | ||||
fnext2 = fcurr2 + ((*pk) * gnext1); | ||||
/* Process third sample for 2nd, 6th .. tap */ | ||||
fnext3 = fcurr3 + ((*pk) * gnext2); | ||||
/* Process fourth sample for 2nd, 6th .. tap */ | ||||
fnext4 = fcurr4 + ((*pk) * gnext3); | ||||
/* g2(n) = f1(n) * K2 + g1(n-1) */ | ||||
/* Calculation of state values for next stage */ | ||||
gnext4 = (fcurr4 * (*pk)) + gnext3; | ||||
gnext3 = (fcurr3 * (*pk)) + gnext2; | ||||
gnext2 = (fcurr2 * (*pk)) + gnext1; | ||||
gnext1 = (fcurr1 * (*pk++)) + gcurr1; | ||||
/* Read g2(n-1), g4(n-1) .... from state */ | ||||
gcurr1 = *px; | ||||
/* save g2(n) in state buffer */ | ||||
*px++ = gnext4; | ||||
/* Sample processing for K3, K7.... */ | ||||
/* Process first sample for 3rd, 7th .. tap */ | ||||
/* f3(n) = f2(n) + K3 * g2(n-1) */ | ||||
fcurr1 = fnext1 + ((*pk) * gcurr1); | ||||
/* Process second sample for 3rd, 7th .. tap */ | ||||
fcurr2 = fnext2 + ((*pk) * gnext1); | ||||
/* Process third sample for 3rd, 7th .. tap */ | ||||
fcurr3 = fnext3 + ((*pk) * gnext2); | ||||
/* Process fourth sample for 3rd, 7th .. tap */ | ||||
fcurr4 = fnext4 + ((*pk) * gnext3); | ||||
/* Calculation of state values for next stage */ | ||||
/* g3(n) = f2(n) * K3 + g2(n-1) */ | ||||
gnext4 = (fnext4 * (*pk)) + gnext3; | ||||
gnext3 = (fnext3 * (*pk)) + gnext2; | ||||
gnext2 = (fnext2 * (*pk)) + gnext1; | ||||
gnext1 = (fnext1 * (*pk++)) + gcurr1; | ||||
/* Read g1(n-1), g3(n-1) .... from state */ | ||||
gcurr1 = *px; | ||||
/* save g3(n) in state buffer */ | ||||
*px++ = gnext4; | ||||
/* Sample processing for K4, K8.... */ | ||||
/* Process first sample for 4th, 8th .. tap */ | ||||
/* f4(n) = f3(n) + K4 * g3(n-1) */ | ||||
fnext1 = fcurr1 + ((*pk) * gcurr1); | ||||
/* Process second sample for 4th, 8th .. tap */ | ||||
/* for sample 2 processing */ | ||||
fnext2 = fcurr2 + ((*pk) * gnext1); | ||||
/* Process third sample for 4th, 8th .. tap */ | ||||
fnext3 = fcurr3 + ((*pk) * gnext2); | ||||
/* Process fourth sample for 4th, 8th .. tap */ | ||||
fnext4 = fcurr4 + ((*pk) * gnext3); | ||||
/* g4(n) = f3(n) * K4 + g3(n-1) */ | ||||
/* Calculation of state values for next stage */ | ||||
gnext4 = (fcurr4 * (*pk)) + gnext3; | ||||
gnext3 = (fcurr3 * (*pk)) + gnext2; | ||||
gnext2 = (fcurr2 * (*pk)) + gnext1; | ||||
gnext1 = (fcurr1 * (*pk++)) + gcurr1; | ||||
/* Read g2(n-1), g4(n-1) .... from state */ | ||||
gcurr1 = *px; | ||||
/* save g4(n) in state buffer */ | ||||
*px++ = gnext4; | ||||
/* Sample processing for K5, K9.... */ | ||||
/* Process first sample for 5th, 9th .. tap */ | ||||
/* f5(n) = f4(n) + K5 * g4(n-1) */ | ||||
fcurr1 = fnext1 + ((*pk) * gcurr1); | ||||
/* Process second sample for 5th, 9th .. tap */ | ||||
fcurr2 = fnext2 + ((*pk) * gnext1); | ||||
/* Process third sample for 5th, 9th .. tap */ | ||||
fcurr3 = fnext3 + ((*pk) * gnext2); | ||||
/* Process fourth sample for 5th, 9th .. tap */ | ||||
fcurr4 = fnext4 + ((*pk) * gnext3); | ||||
/* Calculation of state values for next stage */ | ||||
/* g5(n) = f4(n) * K5 + g4(n-1) */ | ||||
gnext4 = (fnext4 * (*pk)) + gnext3; | ||||
gnext3 = (fnext3 * (*pk)) + gnext2; | ||||
gnext2 = (fnext2 * (*pk)) + gnext1; | ||||
gnext1 = (fnext1 * (*pk++)) + gcurr1; | ||||
stageCnt--; | ||||
} | ||||
/* If the (filter length -1) is not a multiple of 4, compute the remaining filter taps */ | ||||
stageCnt = (numStages - 1u) % 0x4u; | ||||
while(stageCnt > 0u) | ||||
{ | ||||
gcurr1 = *px; | ||||
/* save g value in state buffer */ | ||||
*px++ = gnext4; | ||||
/* Process four samples for last three taps here */ | ||||
fnext1 = fcurr1 + ((*pk) * gcurr1); | ||||
fnext2 = fcurr2 + ((*pk) * gnext1); | ||||
fnext3 = fcurr3 + ((*pk) * gnext2); | ||||
fnext4 = fcurr4 + ((*pk) * gnext3); | ||||
/* g1(n) = f0(n) * K1 + g0(n-1) */ | ||||
gnext4 = (fcurr4 * (*pk)) + gnext3; | ||||
gnext3 = (fcurr3 * (*pk)) + gnext2; | ||||
gnext2 = (fcurr2 * (*pk)) + gnext1; | ||||
gnext1 = (fcurr1 * (*pk++)) + gcurr1; | ||||
/* Update of f values for next coefficient set processing */ | ||||
fcurr1 = fnext1; | ||||
fcurr2 = fnext2; | ||||
fcurr3 = fnext3; | ||||
fcurr4 = fnext4; | ||||
stageCnt--; | ||||
} | ||||
/* The results in the 4 accumulators, store in the destination buffer. */ | ||||
/* y(n) = fN(n) */ | ||||
*pDst++ = fcurr1; | ||||
*pDst++ = fcurr2; | ||||
*pDst++ = fcurr3; | ||||
*pDst++ = fcurr4; | ||||
blkCnt--; | ||||
} | ||||
/* If the blockSize is not a multiple of 4, compute any remaining output samples here. | ||||
** No loop unrolling is used. */ | ||||
blkCnt = blockSize % 0x4u; | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* f0(n) = x(n) */ | ||||
fcurr1 = *pSrc++; | ||||
/* Initialize coeff pointer */ | ||||
pk = (pCoeffs); | ||||
/* Initialize state pointer */ | ||||
px = pState; | ||||
/* read g2(n) from state buffer */ | ||||
gcurr1 = *px; | ||||
/* for sample 1 processing */ | ||||
/* f1(n) = f0(n) + K1 * g0(n-1) */ | ||||
fnext1 = fcurr1 + ((*pk) * gcurr1); | ||||
/* g1(n) = f0(n) * K1 + g0(n-1) */ | ||||
gnext1 = (fcurr1 * (*pk++)) + gcurr1; | ||||
/* 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 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 = fcurr1 + ((*pk) * gcurr1); | ||||
/* g2(n) = f1(n) * K2 + g1(n-1) */ | ||||
gnext1 = (fcurr1 * (*pk++)) + gcurr1; | ||||
/* 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 */ | ||||
float32_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 = fcurr + ((*pk) * gcurr); | ||||
/* g1(n) = f0(n) * K1 + g0(n-1) */ | ||||
gnext = (fcurr * (*pk++)) + gcurr; | ||||
/* save f0(n) in state buffer */ | ||||
*px++ = fcurr; | ||||
/* f1(n) is saved in fcurr | ||||
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 = fcurr + ((*pk) * gcurr); | ||||
/* g2(n) = f1(n) * K2 + g1(n-1) */ | ||||
gnext = (fcurr * (*pk++)) + 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 | ||||
*/ | ||||