diff options
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c | 390 |
1 files changed, 390 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c new file mode 100644 index 0000000..f9a686d --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_fast_q31.c @@ -0,0 +1,390 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_fir_decimate_fast_q31.c
+ * Description: Fast Q31 FIR Decimator
+ *
+ * $Date: 18. March 2019
+ * $Revision: V1.6.0
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "arm_math.h"
+
+/**
+ @ingroup groupFilters
+ */
+
+/**
+ @addtogroup FIR_decimate
+ @{
+ */
+
+/**
+ @brief Processing function for the Q31 FIR decimator (fast variant).
+ @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 samples to process
+ @return none
+
+ @par Scaling and Overflow Behavior
+ 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).
+
+ @remark
+ Refer to \ref arm_fir_decimate_q31() 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 function \ref arm_fir_decimate_init_q31() to initialize the filter structure.
+ */
+
+void arm_fir_decimate_fast_q31(
+ const arm_fir_decimate_instance_q31 * S,
+ const q31_t * pSrc,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ q31_t *pState = S->pState; /* State pointer */
+ const q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ q31_t *pStateCur; /* Points to the current sample of the state */
+ q31_t *px0; /* Temporary pointer for state buffer */
+ const q31_t *pb; /* Temporary pointer for coefficient buffer */
+ q31_t x0, c0; /* Temporary variables to hold state and coefficient values */
+ q63_t acc0; /* Accumulator */
+ uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
+ uint32_t i, tapCnt, blkCnt, outBlockSize = blockSize / S->M; /* Loop counters */
+
+#if defined (ARM_MATH_LOOPUNROLL)
+ q31_t *px1, *px2, *px3;
+ q31_t x1, x2, x3;
+ q63_t acc1, acc2, acc3;
+#endif
+
+ /* S->pState buffer contains previous frame (numTaps - 1) samples */
+ /* pStateCur points to the location where the new input data should be written */
+ pStateCur = S->pState + (numTaps - 1U);
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 samples at a time */
+ blkCnt = outBlockSize >> 2U;
+
+ /* Samples loop unrolled by 4 */
+ while (blkCnt > 0U)
+ {
+ /* Copy 4 * decimation factor number of new input samples into the state buffer */
+ i = S->M * 4;
+
+ do
+ {
+ *pStateCur++ = *pSrc++;
+
+ } while (--i);
+
+ /* Set accumulators to zero */
+ acc0 = 0;
+ acc1 = 0;
+ acc2 = 0;
+ acc3 = 0;
+
+ /* Initialize state pointer for all the samples */
+ px0 = pState;
+ px1 = pState + S->M;
+ px2 = pState + 2 * S->M;
+ px3 = pState + 3 * S->M;
+
+ /* Initialize coeff pointer */
+ pb = pCoeffs;
+
+ /* Loop unrolling: Compute 4 taps at a time */
+ tapCnt = numTaps >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ /* Read the b[numTaps-1] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-1] sample for acc0 */
+ x0 = *(px0++);
+ /* Read x[n-numTaps-1] sample for acc1 */
+ x1 = *(px1++);
+ /* Read x[n-numTaps-1] sample for acc2 */
+ x2 = *(px2++);
+ /* Read x[n-numTaps-1] sample for acc3 */
+ x3 = *(px3++);
+
+ /* 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);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Read the b[numTaps-2] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-2] sample for acc0, acc1, acc2, acc3 */
+ x0 = *(px0++);
+ x1 = *(px1++);
+ x2 = *(px2++);
+ x3 = *(px3++);
+
+ /* 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);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Read the b[numTaps-3] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-3] sample acc0, acc1, acc2, acc3 */
+ x0 = *(px0++);
+ x1 = *(px1++);
+ x2 = *(px2++);
+ x3 = *(px3++);
+
+ /* 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);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-4] sample acc0, acc1, acc2, acc3 */
+ x0 = *(px0++);
+ x1 = *(px1++);
+ x2 = *(px2++);
+ x3 = *(px3++);
+
+ /* 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);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining taps */
+ tapCnt = numTaps % 0x4U;
+
+ while (tapCnt > 0U)
+ {
+ /* Read coefficients */
+ c0 = *(pb++);
+
+ /* Fetch state variables for acc0, acc1, acc2, acc3 */
+ x0 = *(px0++);
+ x1 = *(px1++);
+ x2 = *(px2++);
+ x3 = *(px3++);
+
+ /* 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);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Decrement 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 * 4;
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *pDst++ = (q31_t) (acc0 << 1);
+ *pDst++ = (q31_t) (acc1 << 1);
+ *pDst++ = (q31_t) (acc2 << 1);
+ *pDst++ = (q31_t) (acc3 << 1);
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining samples */
+ blkCnt = outBlockSize % 0x4U;
+
+#else
+
+ /* Initialize blkCnt with number of samples */
+ blkCnt = outBlockSize;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (blkCnt > 0U)
+ {
+ /* Copy decimation factor number of new input samples into the state buffer */
+ i = S->M;
+
+ do
+ {
+ *pStateCur++ = *pSrc++;
+
+ } while (--i);
+
+ /* Set accumulator to zero */
+ acc0 = 0;
+
+ /* Initialize state pointer */
+ px0 = pState;
+
+ /* Initialize coeff pointer */
+ pb = pCoeffs;
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 taps at a time */
+ tapCnt = numTaps >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ /* Read the b[numTaps-1] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-1] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* Read the b[numTaps-2] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-2] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* Read the b[numTaps-3] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-3] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-4] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining taps */
+ tapCnt = numTaps % 0x4U;
+
+#else
+
+ /* Initialize tapCnt with number of taps */
+ tapCnt = numTaps;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (tapCnt > 0U)
+ {
+ /* Read coefficients */
+ c0 = *pb++;
+
+ /* Fetch 1 state variable */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* Decrement 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) (acc0 << 1);
+
+ /* Decrement 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 */
+ pStateCur = S->pState;
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 taps at a time */
+ tapCnt = (numTaps - 1U) >> 2U;
+
+ /* Copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining taps */
+ tapCnt = (numTaps - 1U) % 0x04U;
+
+#else
+
+ /* Initialize tapCnt with number of taps */
+ tapCnt = (numTaps - 1U);
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ /* Copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+}
+
+/**
+ @} end of FIR_decimate group
+ */
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