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Diffstat (limited to 'DSP_Lib/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c')
-rw-r--r-- | DSP_Lib/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c | 351 |
1 files changed, 0 insertions, 351 deletions
diff --git a/DSP_Lib/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c b/DSP_Lib/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c deleted file mode 100644 index 4f01269..0000000 --- a/DSP_Lib/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c +++ /dev/null @@ -1,351 +0,0 @@ -/* ---------------------------------------------------------------------- -* 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_q31.c -* -* Description: Fast Q31 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 Q31 FIR decimator (fast variant) for Cortex-M3 and Cortex-M4. - * @param[in] *S points to an instance of the Q31 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 - * - * <b>Scaling and Overflow Behavior:</b> - * - * \par - * This function is optimized for speed at the expense of fixed-point precision and overflow protection. - * The result of each 1.31 x 1.31 multiplication is truncated to 2.30 format. - * These intermediate results are added to a 2.30 accumulator. - * Finally, the accumulator is saturated and converted to a 1.31 result. - * The fast version has the same overflow behavior as the standard version and provides less precision since it discards the low 32 bits of each multiplication result. - * In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits (where log2 is read as log to the base 2). - * - * \par - * Refer to the function <code>arm_fir_decimate_q31()</code> for a slower implementation of this function which uses a 64-bit accumulator to provide higher precision. - * Both the slow and the fast versions use the same instance structure. - * Use the function <code>arm_fir_decimate_init_q31()</code> to initialize the filter structure. - */ - -void arm_fir_decimate_fast_q31( - arm_fir_decimate_instance_q31 * S, - q31_t * pSrc, - q31_t * pDst, - uint32_t blockSize) -{ - q31_t *pState = S->pState; /* State pointer */ - q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ - q31_t *pStateCurnt; /* Points to the current sample of the state */ - q31_t x0, c0; /* Temporary variables to hold state and coefficient values */ - q31_t *px; /* Temporary pointers for state buffer */ - q31_t *pb; /* Temporary pointers for coefficient buffer */ - q31_t sum0; /* Accumulator */ - uint32_t numTaps = S->numTaps; /* Number of taps */ - uint32_t i, tapCnt, blkCnt, outBlockSize = blockSize / S->M; /* Loop counters */ - uint32_t blkCntN2; - q31_t x1; - q31_t acc0, acc1; - q31_t *px0, *px1; - - /* 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; - blkCntN2 = 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 b[numTaps-1] coefficient */ - c0 = *(pb); - - /* Read x[n-numTaps-1] for sample 0 sample 1 */ - x0 = *(px0); - x1 = *(px1); - - /* Perform the multiply-accumulate */ - acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32); - acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32); - - /* Read the b[numTaps-2] coefficient */ - c0 = *(pb + 1u); - - /* Read x[n-numTaps-2] for sample 0 sample 1 */ - x0 = *(px0 + 1u); - x1 = *(px1 + 1u); - - /* Perform the multiply-accumulate */ - acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32); - acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32); - - /* Read the b[numTaps-3] coefficient */ - c0 = *(pb + 2u); - - /* Read x[n-numTaps-3] for sample 0 sample 1 */ - x0 = *(px0 + 2u); - x1 = *(px1 + 2u); - pb += 4u; - - /* Perform the multiply-accumulate */ - acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32); - acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32); - - /* Read the b[numTaps-4] coefficient */ - c0 = *(pb - 1u); - - /* Read x[n-numTaps-4] for sample 0 sample 1 */ - x0 = *(px0 + 3u); - x1 = *(px1 + 3u); - - - /* Perform the multiply-accumulate */ - acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32); - acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32); - - /* update state pointers */ - px0 += 4u; - px1 += 4u; - - /* 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 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32); - acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32); - - /* 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; - - /* The result is in the accumulator, store in the destination buffer. */ - *pDst++ = (q31_t) (acc0 << 1); - *pDst++ = (q31_t) (acc1 << 1); - - /* Decrement the loop counter */ - blkCnt--; - } - - while(blkCntN2 > 0u) - { - /* Copy decimation factor number of new input samples into the state buffer */ - i = S->M; - - do - { - *pStateCurnt++ = *pSrc++; - - } while(--i); - - /* Set accumulator 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 b[numTaps-1] coefficient */ - c0 = *(pb++); - - /* Read x[n-numTaps-1] sample */ - x0 = *(px++); - - /* Perform the multiply-accumulate */ - sum0 = (q31_t) ((((q63_t) sum0 << 32) + ((q63_t) x0 * c0)) >> 32); - - /* Read the b[numTaps-2] coefficient */ - c0 = *(pb++); - - /* Read x[n-numTaps-2] sample */ - x0 = *(px++); - - /* Perform the multiply-accumulate */ - sum0 = (q31_t) ((((q63_t) sum0 << 32) + ((q63_t) x0 * c0)) >> 32); - - /* Read the b[numTaps-3] coefficient */ - c0 = *(pb++); - - /* Read x[n-numTaps-3] sample */ - x0 = *(px++); - - /* Perform the multiply-accumulate */ - sum0 = (q31_t) ((((q63_t) sum0 << 32) + ((q63_t) x0 * c0)) >> 32); - - /* Read the b[numTaps-4] coefficient */ - c0 = *(pb++); - - /* Read x[n-numTaps-4] sample */ - x0 = *(px++); - - /* Perform the multiply-accumulate */ - sum0 = (q31_t) ((((q63_t) sum0 << 32) + ((q63_t) x0 * c0)) >> 32); - - /* 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 = (q31_t) ((((q63_t) sum0 << 32) + ((q63_t) x0 * c0)) >> 32); - - /* 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; - - /* The result is in the accumulator, store in the destination buffer. */ - *pDst++ = (q31_t) (sum0 << 1); - - /* Decrement the loop counter */ - blkCntN2--; - } - - /* 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--; - } -} - -/** - * @} end of FIR_decimate group - */ |