diff options
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_f32.c | 703 |
1 files changed, 703 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_f32.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_f32.c new file mode 100644 index 0000000..d91543c --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_decimate_f32.c @@ -0,0 +1,703 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_fir_decimate_f32.c
+ * Description: FIR decimation for floating-point sequences
+ *
+ * $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
+ */
+
+/**
+ @defgroup FIR_decimate Finite Impulse Response (FIR) Decimator
+
+ These functions combine an FIR filter together with a decimator.
+ They are used in multirate systems for reducing the sample rate of a signal without introducing aliasing distortion.
+ Conceptually, the functions are equivalent to the block diagram below:
+ \image html FIRDecimator.gif "Components included in the FIR Decimator functions"
+ When decimating by a factor of <code>M</code>, the signal should be prefiltered by a lowpass filter with a normalized
+ cutoff frequency of <code>1/M</code> in order to prevent aliasing distortion.
+ The user of the function is responsible for providing the filter coefficients.
+
+ The FIR decimator functions provided in the CMSIS DSP Library combine the FIR filter and the decimator in an efficient manner.
+ Instead of calculating all of the FIR filter outputs and discarding <code>M-1</code> out of every <code>M</code>, only the
+ samples output by the decimator are computed.
+ The functions operate on blocks of input and output data.
+ <code>pSrc</code> points to an array of <code>blockSize</code> input values and
+ <code>pDst</code> points to an array of <code>blockSize/M</code> output values.
+ In order to have an integer number of output samples <code>blockSize</code>
+ must always be a multiple of the decimation factor <code>M</code>.
+
+ The library provides separate functions for Q15, Q31 and floating-point data types.
+
+ @par Algorithm:
+ The FIR portion of the algorithm uses the standard form filter:
+ <pre>
+ y[n] = b[0] * x[n] + b[1] * x[n-1] + b[2] * x[n-2] + ...+ b[numTaps-1] * x[n-numTaps+1]
+ </pre>
+ where, <code>b[n]</code> are the filter coefficients.
+ @par
+ The <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>.
+ Coefficients are stored in time reversed order.
+ @par
+ <pre>
+ {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
+ </pre>
+ @par
+ <code>pState</code> points to a state array of size <code>numTaps + blockSize - 1</code>.
+ Samples in the state buffer are stored in the order:
+ @par
+ <pre>
+ {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}
+ </pre>
+ The state variables are updated after each block of data is processed, the coefficients are untouched.
+
+ @par Instance Structure
+ The coefficients and state variables for a filter are stored together in an instance data structure.
+ A separate instance structure must be defined for each filter.
+ Coefficient arrays may be shared among several instances while state variable array should be allocated separately.
+ There are separate instance structure declarations for each of the 3 supported data types.
+
+ @par Initialization Functions
+ There is also an associated initialization function for each data type.
+ The initialization function performs the following operations:
+ - Sets the values of the internal structure fields.
+ - Zeros out the values in the state buffer.
+ - Checks to make sure that the size of the input is a multiple of the decimation factor.
+ To do this manually without calling the init function, assign the follow subfields of the instance structure:
+ numTaps, pCoeffs, M (decimation factor), pState. Also set all of the values in pState to zero.
+ @par
+ Use of the initialization function is optional.
+ However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
+ To place an instance structure into a const data section, the instance structure must be manually initialized.
+ The code below statically initializes each of the 3 different data type filter instance structures
+ <pre>
+ arm_fir_decimate_instance_f32 S = {M, numTaps, pCoeffs, pState};
+ arm_fir_decimate_instance_q31 S = {M, numTaps, pCoeffs, pState};
+ arm_fir_decimate_instance_q15 S = {M, numTaps, pCoeffs, pState};
+ </pre>
+ where <code>M</code> is the decimation factor; <code>numTaps</code> is the number of filter coefficients in the filter;
+ <code>pCoeffs</code> is the address of the coefficient buffer;
+ <code>pState</code> is the address of the state buffer.
+ Be sure to set the values in the state buffer to zeros when doing static initialization.
+
+ @par Fixed-Point Behavior
+ Care must be taken when using the fixed-point versions of the FIR decimate filter functions.
+ In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
+ Refer to the function specific documentation below for usage guidelines.
+ */
+
+/**
+ @addtogroup FIR_decimate
+ @{
+ */
+
+/**
+ @brief Processing function for floating-point FIR decimator.
+ @param[in] S points to an instance of the floating-point 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
+ */
+
+#if defined(ARM_MATH_NEON)
+void arm_fir_decimate_f32(
+ const arm_fir_decimate_instance_f32 * S,
+ const float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pState = S->pState; /* State pointer */
+ const float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ float32_t *pStateCurnt; /* Points to the current sample of the state */
+ float32_t *px; /* Temporary pointer for state buffer */
+ const float32_t *pb; /* Temporary pointer for coefficient buffer */
+ float32_t sum0; /* Accumulator */
+ float32_t x0, c0; /* Temporary variables to hold state and coefficient values */
+ uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
+ uint32_t i, tapCnt, blkCnt, outBlockSize = blockSize / S->M; /* Loop counters */
+
+ uint32_t blkCntN4;
+ float32_t *px0, *px1, *px2, *px3;
+ float32_t acc0, acc1, acc2, acc3;
+ float32_t x1, x2, x3;
+
+ float32x4_t accv,acc0v,acc1v,acc2v,acc3v;
+ float32x4_t x0v, x1v, x2v, x3v;
+ float32x4_t c0v;
+ float32x2_t temp;
+ float32x4_t sum0v;
+
+ /* 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 / 4;
+ blkCntN4 = outBlockSize - (4 * blkCnt);
+
+ while (blkCnt > 0U)
+ {
+ /* Copy 4 * decimation factor number of new input samples into the state buffer */
+ i = 4 * S->M;
+
+ do
+ {
+ *pStateCurnt++ = *pSrc++;
+
+ } while (--i);
+
+ /* Set accumulators to zero */
+ acc0v = vdupq_n_f32(0.0);
+ acc1v = vdupq_n_f32(0.0);
+ acc2v = vdupq_n_f32(0.0);
+ acc3v = vdupq_n_f32(0.0);
+
+ /* 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;
+
+ /* Process 4 taps at a time. */
+ tapCnt = numTaps >> 2;
+
+ /* Loop over the number of taps.
+ ** Repeat until we've computed numTaps-4 coefficients. */
+
+ while (tapCnt > 0U)
+ {
+ /* Read the b[numTaps-1] coefficient */
+ c0v = vld1q_f32(pb);
+ pb += 4;
+
+ /* Read x[n-numTaps-1] sample for acc0 */
+ x0v = vld1q_f32(px0);
+ x1v = vld1q_f32(px1);
+ x2v = vld1q_f32(px2);
+ x3v = vld1q_f32(px3);
+
+ px0 += 4;
+ px1 += 4;
+ px2 += 4;
+ px3 += 4;
+
+ acc0v = vmlaq_f32(acc0v, x0v, c0v);
+ acc1v = vmlaq_f32(acc1v, x1v, c0v);
+ acc2v = vmlaq_f32(acc2v, x2v, c0v);
+ acc3v = vmlaq_f32(acc3v, x3v, c0v);
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ temp = vpadd_f32(vget_low_f32(acc0v),vget_high_f32(acc0v));
+ accv[0] = temp[0] + temp[1];
+
+ temp = vpadd_f32(vget_low_f32(acc1v),vget_high_f32(acc1v));
+ accv[1] = temp[0] + temp[1];
+
+ temp = vpadd_f32(vget_low_f32(acc2v),vget_high_f32(acc2v));
+ accv[2] = temp[0] + temp[1];
+
+ temp = vpadd_f32(vget_low_f32(acc3v),vget_high_f32(acc3v));
+ accv[3] = temp[0] + temp[1];
+
+ /* 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 state variables for acc0, acc1, acc2, acc3 */
+ x0 = *(px0++);
+ x1 = *(px1++);
+ x2 = *(px2++);
+ x3 = *(px3++);
+
+ /* Perform the multiply-accumulate */
+ accv[0] += x0 * c0;
+ accv[1] += x1 * c0;
+ accv[2] += x2 * c0;
+ accv[3] += x3 * 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 + 4 * S->M;
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ vst1q_f32(pDst,accv);
+ pDst += 4;
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ while (blkCntN4 > 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 */
+ sum0v = vdupq_n_f32(0.0);
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize coeff pointer */
+ pb = pCoeffs;
+
+ /* Process 4 taps at a time. */
+ tapCnt = numTaps >> 2;
+
+ /* Loop over the number of taps.
+ ** Repeat until we've computed numTaps-4 coefficients. */
+ while (tapCnt > 0U)
+ {
+ c0v = vld1q_f32(pb);
+ pb += 4;
+
+ x0v = vld1q_f32(px);
+ px += 4;
+
+ sum0v = vmlaq_f32(sum0v, x0v, c0v);
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ temp = vpadd_f32(vget_low_f32(sum0v),vget_high_f32(sum0v));
+ sum0 = temp[0] + temp[1];
+
+ /* 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;
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *pDst++ = sum0;
+
+ /* Decrement the loop counter */
+ blkCntN4--;
+ }
+
+ /* 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) >> 2;
+
+ /* Copy data */
+ while (i > 0U)
+ {
+ sum0v = vld1q_f32(pState);
+ vst1q_f32(pStateCurnt,sum0v);
+ pState += 4;
+ pStateCurnt += 4;
+
+ /* 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_f32(
+ const arm_fir_decimate_instance_f32 * S,
+ const float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pState = S->pState; /* State pointer */
+ const float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ float32_t *pStateCur; /* Points to the current sample of the state */
+ float32_t *px0; /* Temporary pointer for state buffer */
+ const float32_t *pb; /* Temporary pointer for coefficient buffer */
+ float32_t x0, c0; /* Temporary variables to hold state and coefficient values */
+ float32_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)
+ float32_t *px1, *px2, *px3;
+ float32_t x1, x2, x3;
+ float32_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 = 0.0f;
+ acc1 = 0.0f;
+ acc2 = 0.0f;
+ acc3 = 0.0f;
+
+ /* 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 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* 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 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* 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 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* 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 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* 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 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* 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++ = acc0;
+ *pDst++ = acc1;
+ *pDst++ = acc2;
+ *pDst++ = acc3;
+
+ /* 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 = 0.0f;
+
+ /* 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 += x0 * c0;
+
+ /* Read the b[numTaps-2] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-2] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 += x0 * c0;
+
+ /* Read the b[numTaps-3] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-3] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 += x0 * c0;
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *pb++;
+
+ /* Read x[n-numTaps-4] sample */
+ x0 = *px0++;
+
+ /* Perform the multiply-accumulate */
+ acc0 += x0 * c0;
+
+ /* 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 += x0 * c0;
+
+ /* 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++ = acc0;
+
+ /* 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--;
+ }
+
+}
+#endif /* #if defined(ARM_MATH_NEON) */
+
+/**
+ @} end of FIR_decimate group
+ */
|