| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010 ARM Limited. All rights reserved. |
| * |
| * $Date: 15. July 2011 |
| * $Revision: V1.0.10 |
| * |
| * Project: CMSIS DSP Library |
| * Title: arm_fir_lattice_q31.c |
| * |
| * Description: Q31 FIR lattice filter processing function. |
| * |
| * 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 |
| */ |
| |
| /** |
| * @addtogroup FIR_Lattice |
| * @{ |
| */ |
| |
| |
| /** |
| * @brief Processing function for the Q31 FIR lattice filter. |
| * @param[in] *S points to an instance of the Q31 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. |
| * |
| * @details |
| * <b>Scaling and Overflow Behavior:</b> |
| * In order to avoid overflows the input signal must be scaled down by 2*log2(numStages) bits. |
| */ |
| |
| void arm_fir_lattice_q31( |
| const arm_fir_lattice_instance_q31 * S, |
| q31_t * pSrc, |
| q31_t * pDst, |
| uint32_t blockSize) |
| { |
| q31_t *pState; /* State pointer */ |
| q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
| q31_t *px; /* temporary state pointer */ |
| q31_t *pk; /* temporary coefficient pointer */ |
| |
| |
| #ifndef ARM_MATH_CM0 |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| |
| q31_t fcurr1, fnext1, gcurr1 = 0, gnext1; /* temporary variables for first sample in loop unrolling */ |
| q63_t fcurr2, fnext2, gnext2; /* temporary variables for second sample in loop unrolling */ |
| q63_t fcurr3, fnext3, gnext3; /* temporary variables for third sample in loop unrolling */ |
| q63_t fcurr4, fnext4, gnext4; /* temporary variables for fourth sample in loop unrolling */ |
| uint32_t numStages = S->numStages; /* Length of the filter */ |
| uint32_t blkCnt, stageCnt; /* temporary variables for counts */ |
| |
| pState = &S->pState[0]; |
| |
| blkCnt = blockSize >> 2u; |
| |
| /* 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++; |
| /* f0(n) = x(n) */ |
| 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 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fcurr1; |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (*pk)) >> 31) + gcurr1; |
| |
| /* Process second sample for first tap */ |
| /* for sample 2 processing */ |
| fnext2 = (q31_t) (((q63_t) fcurr1 * (*pk)) >> 31) + fcurr2; |
| gnext2 = (q31_t) (((q63_t) fcurr2 * (*pk)) >> 31) + 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++ = (q31_t) fcurr4; |
| |
| /* Process third sample for first tap */ |
| fnext3 = (q31_t) (((q63_t) fcurr2 * (*pk)) >> 31) + fcurr3; |
| gnext3 = (q31_t) (((q63_t) fcurr3 * (*pk)) >> 31) + fcurr2; |
| |
| /* Process fourth sample for first tap */ |
| fnext4 = (q31_t) (((q63_t) fcurr3 * (*pk)) >> 31) + fcurr4; |
| gnext4 = (q31_t) (((q63_t) fcurr4 * (*pk++)) >> 31) + fcurr3; |
| |
| /* save g1(n) in state buffer for next sample processing */ |
| /* *px++ = gnext4; */ |
| |
| /* 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++ = (q31_t) gnext4; |
| |
| /* Process first sample for 2nd, 6th .. tap */ |
| /* Sample processing for K2, K6.... */ |
| /* f2(n) = f1(n) + K2 * g1(n-1) */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fcurr1; |
| /* Process second sample for 2nd, 6th .. tap */ |
| /* for sample 2 processing */ |
| fnext2 = (q31_t) (((q63_t) gnext1 * (*pk)) >> 31) + fcurr2; |
| /* Process third sample for 2nd, 6th .. tap */ |
| fnext3 = (q31_t) (((q63_t) gnext2 * (*pk)) >> 31) + fcurr3; |
| /* Process fourth sample for 2nd, 6th .. tap */ |
| fnext4 = (q31_t) (((q63_t) gnext3 * (*pk)) >> 31) + fcurr4; |
| |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| /* Calculation of state values for next stage */ |
| gnext4 = (q31_t) (((q63_t) fcurr4 * (*pk)) >> 31) + gnext3; |
| gnext3 = (q31_t) (((q63_t) fcurr3 * (*pk)) >> 31) + gnext2; |
| gnext2 = (q31_t) (((q63_t) fcurr2 * (*pk)) >> 31) + gnext1; |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (*pk++)) >> 31) + gcurr1; |
| |
| |
| /* Read g2(n-1), g4(n-1) .... from state */ |
| gcurr1 = *px; |
| |
| /* save g2(n) in state buffer */ |
| *px++ = (q31_t) gnext4; |
| |
| /* Sample processing for K3, K7.... */ |
| /* Process first sample for 3rd, 7th .. tap */ |
| /* f3(n) = f2(n) + K3 * g2(n-1) */ |
| fcurr1 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fnext1; |
| /* Process second sample for 3rd, 7th .. tap */ |
| fcurr2 = (q31_t) (((q63_t) gnext1 * (*pk)) >> 31) + fnext2; |
| /* Process third sample for 3rd, 7th .. tap */ |
| fcurr3 = (q31_t) (((q63_t) gnext2 * (*pk)) >> 31) + fnext3; |
| /* Process fourth sample for 3rd, 7th .. tap */ |
| fcurr4 = (q31_t) (((q63_t) gnext3 * (*pk)) >> 31) + fnext4; |
| |
| /* Calculation of state values for next stage */ |
| /* gnext4 = fnext4 * (*pk) + gnext3; */ |
| gnext4 = (q31_t) (((q63_t) fnext4 * (*pk)) >> 31) + gnext3; |
| gnext3 = (q31_t) (((q63_t) fnext3 * (*pk)) >> 31) + gnext2; |
| /* gnext2 = fnext2 * (*pk) + gnext1; */ |
| gnext2 = (q31_t) (((q63_t) fnext2 * (*pk)) >> 31) + gnext1; |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| /* gnext1 = fnext1 * (*pk++) + gcurr1; */ |
| gnext1 = (q31_t) (((q63_t) fnext1 * (*pk++)) >> 31) + gcurr1; |
| |
| /* Read g1(n-1), g3(n-1) .... from state */ |
| gcurr1 = *px; |
| |
| /* save g1(n) in state buffer */ |
| *px++ = (q31_t) gnext4; |
| |
| /* Sample processing for K4, K8.... */ |
| /* Process first sample for 4th, 8th .. tap */ |
| /* f4(n) = f3(n) + K4 * g3(n-1) */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fcurr1; |
| /* Process second sample for 4th, 8th .. tap */ |
| /* for sample 2 processing */ |
| fnext2 = (q31_t) (((q63_t) gnext1 * (*pk)) >> 31) + fcurr2; |
| /* Process third sample for 4th, 8th .. tap */ |
| fnext3 = (q31_t) (((q63_t) gnext2 * (*pk)) >> 31) + fcurr3; |
| /* Process fourth sample for 4th, 8th .. tap */ |
| fnext4 = (q31_t) (((q63_t) gnext3 * (*pk)) >> 31) + fcurr4; |
| |
| /* g4(n) = f3(n) * K4 + g3(n-1) */ |
| /* Calculation of state values for next stage */ |
| gnext4 = (q31_t) (((q63_t) fcurr4 * (*pk)) >> 31) + gnext3; |
| gnext3 = (q31_t) (((q63_t) fcurr3 * (*pk)) >> 31) + gnext2; |
| gnext2 = (q31_t) (((q63_t) fcurr2 * (*pk)) >> 31) + gnext1; |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (*pk++)) >> 31) + gcurr1; |
| |
| /* Read g2(n-1), g4(n-1) .... from state */ |
| gcurr1 = *px; |
| |
| /* save g4(n) in state buffer */ |
| *px++ = (q31_t) gnext4; |
| |
| /* Sample processing for K5, K9.... */ |
| /* Process first sample for 5th, 9th .. tap */ |
| /* f5(n) = f4(n) + K5 * g4(n-1) */ |
| fcurr1 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fnext1; |
| /* Process second sample for 5th, 9th .. tap */ |
| fcurr2 = (q31_t) (((q63_t) gnext1 * (*pk)) >> 31) + fnext2; |
| /* Process third sample for 5th, 9th .. tap */ |
| fcurr3 = (q31_t) (((q63_t) gnext2 * (*pk)) >> 31) + fnext3; |
| /* Process fourth sample for 5th, 9th .. tap */ |
| fcurr4 = (q31_t) (((q63_t) gnext3 * (*pk)) >> 31) + fnext4; |
| |
| /* Calculation of state values for next stage */ |
| /* g5(n) = f4(n) * K5 + g4(n-1) */ |
| gnext4 = (q31_t) (((q63_t) fnext4 * (*pk)) >> 31) + gnext3; |
| gnext3 = (q31_t) (((q63_t) fnext3 * (*pk)) >> 31) + gnext2; |
| gnext2 = (q31_t) (((q63_t) fnext2 * (*pk)) >> 31) + gnext1; |
| gnext1 = (q31_t) (((q63_t) fnext1 * (*pk++)) >> 31) + 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++ = (q31_t) gnext4; |
| |
| /* Process four samples for last three taps here */ |
| fnext1 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fcurr1; |
| fnext2 = (q31_t) (((q63_t) gnext1 * (*pk)) >> 31) + fcurr2; |
| fnext3 = (q31_t) (((q63_t) gnext2 * (*pk)) >> 31) + fcurr3; |
| fnext4 = (q31_t) (((q63_t) gnext3 * (*pk)) >> 31) + fcurr4; |
| |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext4 = (q31_t) (((q63_t) fcurr4 * (*pk)) >> 31) + gnext3; |
| gnext3 = (q31_t) (((q63_t) fcurr3 * (*pk)) >> 31) + gnext2; |
| gnext2 = (q31_t) (((q63_t) fcurr2 * (*pk)) >> 31) + gnext1; |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (*pk++)) >> 31) + 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++ = (q31_t) fcurr2; |
| *pDst++ = (q31_t) fcurr3; |
| *pDst++ = (q31_t) 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 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fcurr1; |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (*pk++)) >> 31) + 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 = (q31_t) (((q63_t) gcurr1 * (*pk)) >> 31) + fcurr1; |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext1 = (q31_t) (((q63_t) fcurr1 * (*pk++)) >> 31) + 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 */ |
| |
| q31_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 = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr; |
| /* g1(n) = f0(n) * K1 + g0(n-1) */ |
| gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr; |
| /* save g1(n) in state buffer */ |
| *px++ = fcurr; |
| |
| /* f1(n) is saved in fcurr1 |
| 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 = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr; |
| /* g2(n) = f1(n) * K2 + g1(n-1) */ |
| gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + 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 |
| */ |
