| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| * |
| * $Date: 19. March 2015 |
| * $Revision: V.1.4.5 |
| * |
| * 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 |
| */ |