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- /* ----------------------------------------------------------------------
- * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
- *
- * $Date: 17. January 2013
- * $Revision: V1.4.1
- *
- * 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
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * - Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * - Neither the name of ARM LIMITED nor the names of its contributors
- * may be used to endorse or promote products derived from this
- * software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- * -------------------------------------------------------------------- */
-
- #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.
- * To do this manually without calling the init function, assign the follow subfields of the instance structure:
- * numStages, pCoeffs, pState. Also set all of the values in pState to zero.
- *
- * \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_FAMILY
-
- /* 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_FAMILY */
-
- }
-
- /**
- * @} end of FIR_Lattice group
- */
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