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author | Ali Labbene <ali.labbene@st.com> | 2019-12-09 11:25:19 +0100 |
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committer | Ali Labbene <ali.labbene@st.com> | 2019-12-10 16:34:57 +0100 |
commit | 76177aa280494bb36d7a0bcbda1078d4db717020 (patch) | |
tree | 1046b1d15478b732a6398bd810a314d2eef1d6f1 /DSP_Lib/Source/FilteringFunctions/arm_fir_q15.c | |
parent | c2b2a927a229ee06e25ebc085d62ce0985dc0ee4 (diff) | |
download | st-cmsis-core-lowfat-76177aa280494bb36d7a0bcbda1078d4db717020.tar.gz st-cmsis-core-lowfat-76177aa280494bb36d7a0bcbda1078d4db717020.tar.bz2 st-cmsis-core-lowfat-76177aa280494bb36d7a0bcbda1078d4db717020.zip |
Official ARM version: v4.5
Diffstat (limited to 'DSP_Lib/Source/FilteringFunctions/arm_fir_q15.c')
-rw-r--r-- | DSP_Lib/Source/FilteringFunctions/arm_fir_q15.c | 691 |
1 files changed, 691 insertions, 0 deletions
diff --git a/DSP_Lib/Source/FilteringFunctions/arm_fir_q15.c b/DSP_Lib/Source/FilteringFunctions/arm_fir_q15.c new file mode 100644 index 0000000..b0d3d09 --- /dev/null +++ b/DSP_Lib/Source/FilteringFunctions/arm_fir_q15.c @@ -0,0 +1,691 @@ +/* ---------------------------------------------------------------------- +* 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_q15.c +* +* Description: Q15 FIR filter processing function. +* +* 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 + */ + +/** + * @addtogroup FIR + * @{ + */ + +/** + * @brief Processing function for the Q15 FIR filter. + * @param[in] *S points to an instance of the Q15 FIR 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. + * + * + * \par Restrictions + * If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE + * In this case input, output, state buffers should be aligned by 32-bit + * + * <b>Scaling and Overflow Behavior:</b> + * \par + * The function is implemented using a 64-bit internal accumulator. + * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result. + * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format. + * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved. + * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits. + * Lastly, the accumulator is saturated to yield a result in 1.15 format. + * + * \par + * Refer to the function <code>arm_fir_fast_q15()</code> for a faster but less precise implementation of this function. + */ + +#ifndef ARM_MATH_CM0_FAMILY + +/* Run the below code for Cortex-M4 and Cortex-M3 */ + +#ifndef UNALIGNED_SUPPORT_DISABLE + + +void arm_fir_q15( + const arm_fir_instance_q15 * S, + q15_t * pSrc, + q15_t * pDst, + uint32_t blockSize) +{ + q15_t *pState = S->pState; /* State pointer */ + q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ + q15_t *pStateCurnt; /* Points to the current sample of the state */ + q15_t *px1; /* Temporary q15 pointer for state buffer */ + q15_t *pb; /* Temporary pointer for coefficient buffer */ + q31_t x0, x1, x2, x3, c0; /* Temporary variables to hold SIMD state and coefficient values */ + q63_t acc0, acc1, acc2, acc3; /* Accumulators */ + uint32_t numTaps = S->numTaps; /* Number of taps in the filter */ + uint32_t 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 >> 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) + { + /* Copy four new input samples into the state buffer. + ** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */ + *__SIMD32(pStateCurnt)++ = *__SIMD32(pSrc)++; + *__SIMD32(pStateCurnt)++ = *__SIMD32(pSrc)++; + + /* Set all accumulators to zero */ + acc0 = 0; + acc1 = 0; + acc2 = 0; + acc3 = 0; + + /* Initialize state pointer of type q15 */ + px1 = pState; + + /* Initialize coeff pointer of type q31 */ + pb = pCoeffs; + + /* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */ + x0 = _SIMD32_OFFSET(px1); + + /* Read the third and forth samples from the state buffer: x[n-N-1], x[n-N-2] */ + x1 = _SIMD32_OFFSET(px1 + 1u); + + px1 += 2u; + + /* Loop over the number of taps. Unroll by a factor of 4. + ** Repeat until we've computed numTaps-4 coefficients. */ + tapCnt = numTaps >> 2; + + while(tapCnt > 0u) + { + /* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */ + c0 = *__SIMD32(pb)++; + + /* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */ + acc0 = __SMLALD(x0, c0, acc0); + + /* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */ + acc1 = __SMLALD(x1, c0, acc1); + + /* Read state x[n-N-2], x[n-N-3] */ + x2 = _SIMD32_OFFSET(px1); + + /* Read state x[n-N-3], x[n-N-4] */ + x3 = _SIMD32_OFFSET(px1 + 1u); + + /* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */ + acc2 = __SMLALD(x2, c0, acc2); + + /* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */ + acc3 = __SMLALD(x3, c0, acc3); + + /* Read coefficients b[N-2], b[N-3] */ + c0 = *__SIMD32(pb)++; + + /* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */ + acc0 = __SMLALD(x2, c0, acc0); + + /* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */ + acc1 = __SMLALD(x3, c0, acc1); + + /* Read state x[n-N-4], x[n-N-5] */ + x0 = _SIMD32_OFFSET(px1 + 2u); + + /* Read state x[n-N-5], x[n-N-6] */ + x1 = _SIMD32_OFFSET(px1 + 3u); + + /* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */ + acc2 = __SMLALD(x0, c0, acc2); + + /* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */ + acc3 = __SMLALD(x1, c0, acc3); + + px1 += 4u; + + tapCnt--; + + } + + + /* If the filter length is not a multiple of 4, compute the remaining filter taps. + ** This is always be 2 taps since the filter length is even. */ + if((numTaps & 0x3u) != 0u) + { + /* Read 2 coefficients */ + c0 = *__SIMD32(pb)++; + + /* Fetch 4 state variables */ + x2 = _SIMD32_OFFSET(px1); + + x3 = _SIMD32_OFFSET(px1 + 1u); + + /* Perform the multiply-accumulates */ + acc0 = __SMLALD(x0, c0, acc0); + + px1 += 2u; + + acc1 = __SMLALD(x1, c0, acc1); + acc2 = __SMLALD(x2, c0, acc2); + acc3 = __SMLALD(x3, c0, acc3); + } + + /* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation. + ** Then store the 4 outputs in the destination buffer. */ + +#ifndef ARM_MATH_BIG_ENDIAN + + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16); + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16); + +#else + + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16); + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16); + +#endif /* #ifndef ARM_MATH_BIG_ENDIAN */ + + + + /* Advance the state pointer by 4 to process the next group of 4 samples */ + pState = pState + 4; + + /* Decrement the loop counter */ + 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) + { + /* Copy two samples into state buffer */ + *pStateCurnt++ = *pSrc++; + + /* Set the accumulator to zero */ + acc0 = 0; + + /* Initialize state pointer of type q15 */ + px1 = pState; + + /* Initialize coeff pointer of type q31 */ + pb = pCoeffs; + + tapCnt = numTaps >> 1; + + do + { + + c0 = *__SIMD32(pb)++; + x0 = *__SIMD32(px1)++; + + acc0 = __SMLALD(x0, c0, acc0); + tapCnt--; + } + while(tapCnt > 0u); + + /* The result is in 2.30 format. Convert to 1.15 with saturation. + ** Then store the output in the destination buffer. */ + *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16)); + + /* Advance state pointer by 1 for the next sample */ + pState = pState + 1; + + /* Decrement the loop counter */ + 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; + + /* Calculation of count for copying integer writes */ + tapCnt = (numTaps - 1u) >> 2; + + while(tapCnt > 0u) + { + + /* Copy state values to start of state buffer */ + *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; + *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; + + tapCnt--; + + } + + /* Calculation of count for remaining q15_t data */ + tapCnt = (numTaps - 1u) % 0x4u; + + /* copy remaining data */ + while(tapCnt > 0u) + { + *pStateCurnt++ = *pState++; + + /* Decrement the loop counter */ + tapCnt--; + } +} + +#else /* UNALIGNED_SUPPORT_DISABLE */ + +void arm_fir_q15( + const arm_fir_instance_q15 * S, + q15_t * pSrc, + q15_t * pDst, + uint32_t blockSize) +{ + q15_t *pState = S->pState; /* State pointer */ + q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ + q15_t *pStateCurnt; /* Points to the current sample of the state */ + q63_t acc0, acc1, acc2, acc3; /* Accumulators */ + q15_t *pb; /* Temporary pointer for coefficient buffer */ + q15_t *px; /* Temporary q31 pointer for SIMD state buffer accesses */ + q31_t x0, x1, x2, c0; /* Temporary variables to hold SIMD state and coefficient values */ + uint32_t numTaps = S->numTaps; /* Number of taps in the filter */ + uint32_t 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 >> 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) + { + /* Copy four new input samples into the state buffer. + ** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */ + *pStateCurnt++ = *pSrc++; + *pStateCurnt++ = *pSrc++; + *pStateCurnt++ = *pSrc++; + *pStateCurnt++ = *pSrc++; + + + /* Set all accumulators to zero */ + acc0 = 0; + acc1 = 0; + acc2 = 0; + acc3 = 0; + + /* Typecast q15_t pointer to q31_t pointer for state reading in q31_t */ + px = pState; + + /* Typecast q15_t pointer to q31_t pointer for coefficient reading in q31_t */ + pb = pCoeffs; + + /* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */ + x0 = *__SIMD32(px)++; + + /* Read the third and forth samples from the state buffer: x[n-N-2], x[n-N-3] */ + x2 = *__SIMD32(px)++; + + /* Loop over the number of taps. Unroll by a factor of 4. + ** Repeat until we've computed numTaps-(numTaps%4) coefficients. */ + tapCnt = numTaps >> 2; + + while(tapCnt > 0) + { + /* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */ + c0 = *__SIMD32(pb)++; + + /* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */ + acc0 = __SMLALD(x0, c0, acc0); + + /* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */ + acc2 = __SMLALD(x2, c0, acc2); + + /* pack x[n-N-1] and x[n-N-2] */ +#ifndef ARM_MATH_BIG_ENDIAN + x1 = __PKHBT(x2, x0, 0); +#else + x1 = __PKHBT(x0, x2, 0); +#endif + + /* Read state x[n-N-4], x[n-N-5] */ + x0 = _SIMD32_OFFSET(px); + + /* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */ + acc1 = __SMLALDX(x1, c0, acc1); + + /* pack x[n-N-3] and x[n-N-4] */ +#ifndef ARM_MATH_BIG_ENDIAN + x1 = __PKHBT(x0, x2, 0); +#else + x1 = __PKHBT(x2, x0, 0); +#endif + + /* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */ + acc3 = __SMLALDX(x1, c0, acc3); + + /* Read coefficients b[N-2], b[N-3] */ + c0 = *__SIMD32(pb)++; + + /* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */ + acc0 = __SMLALD(x2, c0, acc0); + + /* Read state x[n-N-6], x[n-N-7] with offset */ + x2 = _SIMD32_OFFSET(px + 2u); + + /* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */ + acc2 = __SMLALD(x0, c0, acc2); + + /* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */ + acc1 = __SMLALDX(x1, c0, acc1); + + /* pack x[n-N-5] and x[n-N-6] */ +#ifndef ARM_MATH_BIG_ENDIAN + x1 = __PKHBT(x2, x0, 0); +#else + x1 = __PKHBT(x0, x2, 0); +#endif + + /* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */ + acc3 = __SMLALDX(x1, c0, acc3); + + /* Update state pointer for next state reading */ + px += 4u; + + /* Decrement tap count */ + tapCnt--; + + } + + /* If the filter length is not a multiple of 4, compute the remaining filter taps. + ** This is always be 2 taps since the filter length is even. */ + if((numTaps & 0x3u) != 0u) + { + + /* Read last two coefficients */ + c0 = *__SIMD32(pb)++; + + /* Perform the multiply-accumulates */ + acc0 = __SMLALD(x0, c0, acc0); + acc2 = __SMLALD(x2, c0, acc2); + + /* pack state variables */ +#ifndef ARM_MATH_BIG_ENDIAN + x1 = __PKHBT(x2, x0, 0); +#else + x1 = __PKHBT(x0, x2, 0); +#endif + + /* Read last state variables */ + x0 = *__SIMD32(px); + + /* Perform the multiply-accumulates */ + acc1 = __SMLALDX(x1, c0, acc1); + + /* pack state variables */ +#ifndef ARM_MATH_BIG_ENDIAN + x1 = __PKHBT(x0, x2, 0); +#else + x1 = __PKHBT(x2, x0, 0); +#endif + + /* Perform the multiply-accumulates */ + acc3 = __SMLALDX(x1, c0, acc3); + } + + /* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation. + ** Then store the 4 outputs in the destination buffer. */ + +#ifndef ARM_MATH_BIG_ENDIAN + + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16); + + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16); + +#else + + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16); + + *__SIMD32(pDst)++ = + __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16); + +#endif /* #ifndef ARM_MATH_BIG_ENDIAN */ + + /* Advance the state pointer by 4 to process the next group of 4 samples */ + pState = pState + 4; + + /* Decrement the loop counter */ + 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) + { + /* Copy two samples into state buffer */ + *pStateCurnt++ = *pSrc++; + + /* Set the accumulator to zero */ + acc0 = 0; + + /* Use SIMD to hold states and coefficients */ + px = pState; + pb = pCoeffs; + + tapCnt = numTaps >> 1u; + + do + { + acc0 += (q31_t) * px++ * *pb++; + acc0 += (q31_t) * px++ * *pb++; + tapCnt--; + } + while(tapCnt > 0u); + + /* The result is in 2.30 format. Convert to 1.15 with saturation. + ** Then store the output in the destination buffer. */ + *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16)); + + /* Advance state pointer by 1 for the next sample */ + pState = pState + 1u; + + /* Decrement the loop counter */ + 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; + + /* Calculation of count for copying integer writes */ + tapCnt = (numTaps - 1u) >> 2; + + while(tapCnt > 0u) + { + *pStateCurnt++ = *pState++; + *pStateCurnt++ = *pState++; + *pStateCurnt++ = *pState++; + *pStateCurnt++ = *pState++; + + tapCnt--; + + } + + /* Calculation of count for remaining q15_t data */ + tapCnt = (numTaps - 1u) % 0x4u; + + /* copy remaining data */ + while(tapCnt > 0u) + { + *pStateCurnt++ = *pState++; + + /* Decrement the loop counter */ + tapCnt--; + } +} + + +#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */ + +#else /* ARM_MATH_CM0_FAMILY */ + + +/* Run the below code for Cortex-M0 */ + +void arm_fir_q15( + const arm_fir_instance_q15 * S, + q15_t * pSrc, + q15_t * pDst, + uint32_t blockSize) +{ + q15_t *pState = S->pState; /* State pointer */ + q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ + q15_t *pStateCurnt; /* Points to the current sample of the state */ + + + + q15_t *px; /* Temporary pointer for state buffer */ + q15_t *pb; /* Temporary pointer for coefficient buffer */ + q63_t acc; /* Accumulator */ + uint32_t numTaps = S->numTaps; /* Number of nTaps in the filter */ + uint32_t tapCnt, blkCnt; /* Loop counters */ + + /* S->pState buffer 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; + + /* Initialize state pointer */ + px = pState; + + /* Initialize Coefficient pointer */ + pb = pCoeffs; + + tapCnt = 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 += (q31_t) * px++ * *pb++; + tapCnt--; + } while(tapCnt > 0u); + + /* The result is in 2.30 format. Convert to 1.15 + ** Then store the output in the destination buffer. */ + *pDst++ = (q15_t) __SSAT((acc >> 15u), 16); + + /* Advance state pointer by 1 for the next sample */ + pState = pState + 1; + + /* Decrement the samples loop counter */ + 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; + + /* 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_FAMILY */ + + + + +/** + * @} end of FIR group + */ |