| /* ---------------------------------------------------------------------- |
| * 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_decimate_fast_q15.c |
| * |
| * Description: Fast Q15 FIR Decimator. |
| * |
| * Target Processor: Cortex-M4/Cortex-M3 |
| * |
| * 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_decimate |
| * @{ |
| */ |
| |
| /** |
| * @brief Processing function for the Q15 FIR decimator (fast variant) for Cortex-M3 and Cortex-M4. |
| * @param[in] *S points to an instance of the Q15 FIR decimator 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 input 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 |
| * This fast version uses a 32-bit accumulator with 2.30 format. |
| * The accumulator maintains full precision of the intermediate multiplication results but provides only a single guard bit. |
| * Thus, if the accumulator result overflows it wraps around and distorts the result. |
| * In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits (log2 is read as log to the base 2). |
| * The 2.30 accumulator is then truncated to 2.15 format and saturated to yield the 1.15 result. |
| * |
| * \par |
| * Refer to the function <code>arm_fir_decimate_q15()</code> for a slower implementation of this function which uses 64-bit accumulation to avoid wrap around distortion. |
| * Both the slow and the fast versions use the same instance structure. |
| * Use the function <code>arm_fir_decimate_init_q15()</code> to initialize the filter structure. |
| */ |
| |
| #ifndef UNALIGNED_SUPPORT_DISABLE |
| |
| void arm_fir_decimate_fast_q15( |
| const arm_fir_decimate_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 coefficient buffer */ |
| q31_t x0, x1, c0, c1; /* Temporary variables to hold state and coefficient values */ |
| q31_t sum0; /* Accumulators */ |
| q31_t acc0, acc1; |
| q15_t *px0, *px1; |
| uint32_t blkCntN3; |
| uint32_t numTaps = S->numTaps; /* Number of taps */ |
| uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* 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); |
| |
| |
| /* Total number of output samples to be computed */ |
| blkCnt = outBlockSize / 2; |
| blkCntN3 = outBlockSize - (2 * blkCnt); |
| |
| |
| while(blkCnt > 0u) |
| { |
| /* Copy decimation factor number of new input samples into the state buffer */ |
| i = 2 * S->M; |
| |
| do |
| { |
| *pStateCurnt++ = *pSrc++; |
| |
| } while(--i); |
| |
| /* Set accumulator to zero */ |
| acc0 = 0; |
| acc1 = 0; |
| |
| /* Initialize state pointer */ |
| px0 = pState; |
| |
| px1 = pState + S->M; |
| |
| |
| /* Initialize coeff pointer */ |
| pb = pCoeffs; |
| |
| /* Loop unrolling. Process 4 taps at a time. */ |
| tapCnt = numTaps >> 2; |
| |
| /* Loop over the number of taps. Unroll by a factor of 4. |
| ** Repeat until we've computed numTaps-4 coefficients. */ |
| while(tapCnt > 0u) |
| { |
| /* Read the Read b[numTaps-1] and b[numTaps-2] coefficients */ |
| c0 = *__SIMD32(pb)++; |
| |
| /* Read x[n-numTaps-1] and x[n-numTaps-2]sample */ |
| x0 = *__SIMD32(px0)++; |
| |
| x1 = *__SIMD32(px1)++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 = __SMLAD(x0, c0, acc0); |
| |
| acc1 = __SMLAD(x1, c0, acc1); |
| |
| /* Read the b[numTaps-3] and b[numTaps-4] coefficient */ |
| c0 = *__SIMD32(pb)++; |
| |
| /* Read x[n-numTaps-2] and x[n-numTaps-3] sample */ |
| x0 = *__SIMD32(px0)++; |
| |
| x1 = *__SIMD32(px1)++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 = __SMLAD(x0, c0, acc0); |
| |
| acc1 = __SMLAD(x1, c0, acc1); |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
| tapCnt = numTaps % 0x4u; |
| |
| while(tapCnt > 0u) |
| { |
| /* Read coefficients */ |
| c0 = *pb++; |
| |
| /* Fetch 1 state variable */ |
| x0 = *px0++; |
| |
| x1 = *px1++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 = __SMLAD(x0, c0, acc0); |
| acc1 = __SMLAD(x1, c0, acc1); |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* Advance the state pointer by the decimation factor |
| * to process the next group of decimation factor number samples */ |
| pState = pState + S->M * 2; |
| |
| /* Store filter output, smlad returns the values in 2.14 format */ |
| /* so downsacle by 15 to get output in 1.15 */ |
| *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16)); |
| *pDst++ = (q15_t) (__SSAT((acc1 >> 15), 16)); |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| |
| |
| while(blkCntN3 > 0u) |
| { |
| /* Copy decimation factor number of new input samples into the state buffer */ |
| i = S->M; |
| |
| do |
| { |
| *pStateCurnt++ = *pSrc++; |
| |
| } while(--i); |
| |
| /*Set sum to zero */ |
| sum0 = 0; |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* Initialize coeff pointer */ |
| pb = pCoeffs; |
| |
| /* Loop unrolling. Process 4 taps at a time. */ |
| tapCnt = numTaps >> 2; |
| |
| /* Loop over the number of taps. Unroll by a factor of 4. |
| ** Repeat until we've computed numTaps-4 coefficients. */ |
| while(tapCnt > 0u) |
| { |
| /* Read the Read b[numTaps-1] and b[numTaps-2] coefficients */ |
| c0 = *__SIMD32(pb)++; |
| |
| /* Read x[n-numTaps-1] and x[n-numTaps-2]sample */ |
| x0 = *__SIMD32(px)++; |
| |
| /* Read the b[numTaps-3] and b[numTaps-4] coefficient */ |
| c1 = *__SIMD32(pb)++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 = __SMLAD(x0, c0, sum0); |
| |
| /* Read x[n-numTaps-2] and x[n-numTaps-3] sample */ |
| x0 = *__SIMD32(px)++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 = __SMLAD(x0, c1, sum0); |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
| tapCnt = numTaps % 0x4u; |
| |
| while(tapCnt > 0u) |
| { |
| /* Read coefficients */ |
| c0 = *pb++; |
| |
| /* Fetch 1 state variable */ |
| x0 = *px++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 = __SMLAD(x0, c0, sum0); |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* Advance the state pointer by the decimation factor |
| * to process the next group of decimation factor number samples */ |
| pState = pState + S->M; |
| |
| /* Store filter output, smlad returns the values in 2.14 format */ |
| /* so downsacle by 15 to get output in 1.15 */ |
| *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); |
| |
| /* Decrement the loop counter */ |
| blkCntN3--; |
| } |
| |
| /* 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; |
| |
| i = (numTaps - 1u) >> 2u; |
| |
| /* copy data */ |
| while(i > 0u) |
| { |
| *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; |
| *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; |
| |
| /* Decrement the loop counter */ |
| i--; |
| } |
| |
| i = (numTaps - 1u) % 0x04u; |
| |
| /* copy data */ |
| while(i > 0u) |
| { |
| *pStateCurnt++ = *pState++; |
| |
| /* Decrement the loop counter */ |
| i--; |
| } |
| } |
| |
| #else |
| |
| |
| void arm_fir_decimate_fast_q15( |
| const arm_fir_decimate_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 coefficient buffer */ |
| q15_t x0, x1, c0; /* Temporary variables to hold state and coefficient values */ |
| q31_t sum0; /* Accumulators */ |
| q31_t acc0, acc1; |
| q15_t *px0, *px1; |
| uint32_t blkCntN3; |
| uint32_t numTaps = S->numTaps; /* Number of taps */ |
| uint32_t i, blkCnt, tapCnt, outBlockSize = blockSize / S->M; /* 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); |
| |
| |
| /* Total number of output samples to be computed */ |
| blkCnt = outBlockSize / 2; |
| blkCntN3 = outBlockSize - (2 * blkCnt); |
| |
| while(blkCnt > 0u) |
| { |
| /* Copy decimation factor number of new input samples into the state buffer */ |
| i = 2 * S->M; |
| |
| do |
| { |
| *pStateCurnt++ = *pSrc++; |
| |
| } while(--i); |
| |
| /* Set accumulator to zero */ |
| acc0 = 0; |
| acc1 = 0; |
| |
| /* Initialize state pointer */ |
| px0 = pState; |
| |
| px1 = pState + S->M; |
| |
| |
| /* Initialize coeff pointer */ |
| pb = pCoeffs; |
| |
| /* Loop unrolling. Process 4 taps at a time. */ |
| tapCnt = numTaps >> 2; |
| |
| /* Loop over the number of taps. Unroll by a factor of 4. |
| ** Repeat until we've computed numTaps-4 coefficients. */ |
| while(tapCnt > 0u) |
| { |
| /* Read the Read b[numTaps-1] coefficients */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-1] for sample 0 and for sample 1 */ |
| x0 = *px0++; |
| x1 = *px1++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 += x0 * c0; |
| acc1 += x1 * c0; |
| |
| /* Read the b[numTaps-2] coefficient */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-2] for sample 0 and sample 1 */ |
| x0 = *px0++; |
| x1 = *px1++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 += x0 * c0; |
| acc1 += x1 * c0; |
| |
| /* Read the b[numTaps-3] coefficients */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-3] for sample 0 and sample 1 */ |
| x0 = *px0++; |
| x1 = *px1++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 += x0 * c0; |
| acc1 += x1 * c0; |
| |
| /* Read the b[numTaps-4] coefficient */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-4] for sample 0 and sample 1 */ |
| x0 = *px0++; |
| x1 = *px1++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 += x0 * c0; |
| acc1 += x1 * c0; |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
| tapCnt = numTaps % 0x4u; |
| |
| while(tapCnt > 0u) |
| { |
| /* Read coefficients */ |
| c0 = *pb++; |
| |
| /* Fetch 1 state variable */ |
| x0 = *px0++; |
| x1 = *px1++; |
| |
| /* Perform the multiply-accumulate */ |
| acc0 += x0 * c0; |
| acc1 += x1 * c0; |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* Advance the state pointer by the decimation factor |
| * to process the next group of decimation factor number samples */ |
| pState = pState + S->M * 2; |
| |
| /* Store filter output, smlad returns the values in 2.14 format */ |
| /* so downsacle by 15 to get output in 1.15 */ |
| |
| *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16)); |
| *pDst++ = (q15_t) (__SSAT((acc1 >> 15), 16)); |
| |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| while(blkCntN3 > 0u) |
| { |
| /* Copy decimation factor number of new input samples into the state buffer */ |
| i = S->M; |
| |
| do |
| { |
| *pStateCurnt++ = *pSrc++; |
| |
| } while(--i); |
| |
| /*Set sum to zero */ |
| sum0 = 0; |
| |
| /* Initialize state pointer */ |
| px = pState; |
| |
| /* Initialize coeff pointer */ |
| pb = pCoeffs; |
| |
| /* Loop unrolling. Process 4 taps at a time. */ |
| tapCnt = numTaps >> 2; |
| |
| /* Loop over the number of taps. Unroll by a factor of 4. |
| ** Repeat until we've computed numTaps-4 coefficients. */ |
| while(tapCnt > 0u) |
| { |
| /* Read the Read b[numTaps-1] coefficients */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-1] and sample */ |
| x0 = *px++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 += x0 * c0; |
| |
| /* Read the b[numTaps-2] coefficient */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-2] and sample */ |
| x0 = *px++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 += x0 * c0; |
| |
| /* Read the b[numTaps-3] coefficients */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-3] sample */ |
| x0 = *px++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 += x0 * c0; |
| |
| /* Read the b[numTaps-4] coefficient */ |
| c0 = *pb++; |
| |
| /* Read x[n-numTaps-4] sample */ |
| x0 = *px++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 += x0 * c0; |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* If the filter length is not a multiple of 4, compute the remaining filter taps */ |
| tapCnt = numTaps % 0x4u; |
| |
| while(tapCnt > 0u) |
| { |
| /* Read coefficients */ |
| c0 = *pb++; |
| |
| /* Fetch 1 state variable */ |
| x0 = *px++; |
| |
| /* Perform the multiply-accumulate */ |
| sum0 += x0 * c0; |
| |
| /* Decrement the loop counter */ |
| tapCnt--; |
| } |
| |
| /* Advance the state pointer by the decimation factor |
| * to process the next group of decimation factor number samples */ |
| pState = pState + S->M; |
| |
| /* Store filter output, smlad returns the values in 2.14 format */ |
| /* so downsacle by 15 to get output in 1.15 */ |
| *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); |
| |
| /* Decrement the loop counter */ |
| blkCntN3--; |
| } |
| |
| /* 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; |
| |
| i = (numTaps - 1u) >> 2u; |
| |
| /* copy data */ |
| while(i > 0u) |
| { |
| *pStateCurnt++ = *pState++; |
| *pStateCurnt++ = *pState++; |
| *pStateCurnt++ = *pState++; |
| *pStateCurnt++ = *pState++; |
| |
| /* Decrement the loop counter */ |
| i--; |
| } |
| |
| i = (numTaps - 1u) % 0x04u; |
| |
| /* copy data */ |
| while(i > 0u) |
| { |
| *pStateCurnt++ = *pState++; |
| |
| /* Decrement the loop counter */ |
| i--; |
| } |
| } |
| |
| |
| #endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */ |
| |
| /** |
| * @} end of FIR_decimate group |
| */ |