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Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_interpolate_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_interpolate_f32.c | 914 |
1 files changed, 914 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_interpolate_f32.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_interpolate_f32.c new file mode 100644 index 0000000..471f25f --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_interpolate_f32.c @@ -0,0 +1,914 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_fir_interpolate_f32.c
+ * Description: Floating-point FIR interpolation 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"
+
+/**
+ @defgroup FIR_Interpolate Finite Impulse Response (FIR) Interpolator
+
+ These functions combine an upsampler (zero stuffer) and an FIR filter.
+ They are used in multirate systems for increasing the sample rate of a signal without introducing high frequency images.
+ Conceptually, the functions are equivalent to the block diagram below:
+ \image html FIRInterpolator.gif "Components included in the FIR Interpolator functions"
+ After upsampling by a factor of <code>L</code>, the signal should be filtered by a lowpass filter with a normalized
+ cutoff frequency of <code>1/L</code> in order to eliminate high frequency copies of the spectrum.
+ The user of the function is responsible for providing the filter coefficients.
+
+ The FIR interpolator functions provided in the CMSIS DSP Library combine the upsampler and FIR filter in an efficient manner.
+ The upsampler inserts <code>L-1</code> zeros between each sample.
+ Instead of multiplying by these zero values, the FIR filter is designed to skip them.
+ This leads to an efficient implementation without any wasted effort.
+ 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*L</code> output values.
+
+ The library provides separate functions for Q15, Q31, and floating-point data types.
+
+ @par Algorithm
+ The functions use a polyphase filter structure:
+ <pre>
+ y[n] = b[0] * x[n] + b[L] * x[n-1] + ... + b[L*(phaseLength-1)] * x[n-phaseLength+1]
+ y[n+1] = b[1] * x[n] + b[L+1] * x[n-1] + ... + b[L*(phaseLength-1)+1] * x[n-phaseLength+1]
+ ...
+ y[n+(L-1)] = b[L-1] * x[n] + b[2*L-1] * x[n-1] + ....+ b[L*(phaseLength-1)+(L-1)] * x[n-phaseLength+1]
+ </pre>
+ This approach is more efficient than straightforward upsample-then-filter algorithms.
+ With this method the computation is reduced by a factor of <code>1/L</code> when compared to using a standard FIR filter.
+ @par
+ <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>.
+ <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code> and this is checked by the
+ initialization functions.
+ Internally, the function divides the FIR filter's impulse response into shorter filters of length
+ <code>phaseLength=numTaps/L</code>.
+ Coefficients are stored in time reversed order.
+ <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>blockSize + phaseLength - 1</code>.
+ Samples in the state buffer are stored in the order:
+ <pre>
+ {x[n-phaseLength+1], x[n-phaseLength], x[n-phaseLength-1], x[n-phaseLength-2]....x[0], x[1], ..., x[blockSize-1]}
+ </pre>
+ @par
+ 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 length of the filter is a multiple of the interpolation factor.
+ To do this manually without calling the init function, assign the follow subfields of the instance structure:
+ L (interpolation factor), pCoeffs, phaseLength (numTaps / L), 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_interpolate_instance_f32 S = {L, phaseLength, pCoeffs, pState};
+ arm_fir_interpolate_instance_q31 S = {L, phaseLength, pCoeffs, pState};
+ arm_fir_interpolate_instance_q15 S = {L, phaseLength, pCoeffs, pState};
+ </pre>
+ @par
+ where <code>L</code> is the interpolation factor; <code>phaseLength=numTaps/L</code> is the
+ length of each of the shorter FIR filters used internally,
+ <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 interpolate 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_Interpolate
+ @{
+ */
+
+/**
+ @brief Processing function for floating-point FIR interpolator.
+ @param[in] S points to an instance of the floating-point FIR interpolator 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_interpolate_f32(
+ const arm_fir_interpolate_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 *ptr1; /* Temporary pointers for state buffer */
+ const float32_t *ptr2; /* Temporary pointers for coefficient buffer */
+ float32_t sum0; /* Accumulators */
+ float32_t x0, c0; /* Temporary variables to hold state and coefficient values */
+ uint32_t i, blkCnt, j; /* Loop counters */
+ uint16_t phaseLen = S->phaseLength, tapCnt; /* Length of each polyphase filter component */
+ float32_t acc0, acc1, acc2, acc3;
+ float32_t x1, x2, x3;
+ uint32_t blkCntN4;
+ float32_t c1, c2, c3;
+
+ float32x4_t sum0v;
+ float32x4_t accV,accV0,accV1;
+ float32x4_t x0v,x1v,x2v,xa,xb;
+ uint32x4_t x0v_u,x1v_u,x2v_u,xa_u,xb_u;
+ float32x2_t tempV;
+
+ /* S->pState buffer contains previous frame (phaseLen - 1) samples */
+ /* pStateCurnt points to the location where the new input data should be written */
+ pStateCurnt = S->pState + (phaseLen - 1U);
+
+ /* Initialise blkCnt */
+ blkCnt = blockSize >> 3;
+ blkCntN4 = blockSize & 7;
+
+ /* Loop unrolling */
+ while (blkCnt > 0U)
+ {
+ /* Copy new input samples into the state buffer */
+ sum0v = vld1q_f32(pSrc);
+ vst1q_f32(pStateCurnt,sum0v);
+ pSrc += 4;
+ pStateCurnt += 4;
+
+ sum0v = vld1q_f32(pSrc);
+ vst1q_f32(pStateCurnt,sum0v);
+ pSrc += 4;
+ pStateCurnt += 4;
+
+ /* Address modifier index of coefficient buffer */
+ j = 1U;
+
+ /* Loop over the Interpolation factor. */
+ i = (S->L);
+
+ while (i > 0U)
+ {
+ /* Set accumulator to zero */
+ accV0 = vdupq_n_f32(0.0);
+ accV1 = vdupq_n_f32(0.0);
+
+ /* Initialize state pointer */
+ ptr1 = pState;
+
+ /* Initialize coefficient pointer */
+ ptr2 = pCoeffs + (S->L - j);
+
+ /* Loop over the polyPhase length. Unroll by a factor of 4.
+ ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
+ tapCnt = phaseLen >> 2U;
+
+ x0v = vld1q_f32(ptr1);
+ x1v = vld1q_f32(ptr1 + 4);
+
+ while (tapCnt > 0U)
+ {
+ /* Read the input samples */
+ x2v = vld1q_f32(ptr1 + 8);
+
+ /* Read the coefficients */
+ c0 = *(ptr2);
+
+ /* Perform the multiply-accumulate */
+ accV0 = vmlaq_n_f32(accV0,x0v,c0);
+ accV1 = vmlaq_n_f32(accV1,x1v,c0);
+
+ /* Read the coefficients, inputs and perform multiply-accumulate */
+ c1 = *(ptr2 + S->L);
+
+ xa = vextq_f32(x0v,x1v,1);
+ xb = vextq_f32(x1v,x2v,1);
+
+ accV0 = vmlaq_n_f32(accV0,xa,c1);
+ accV1 = vmlaq_n_f32(accV1,xb,c1);
+
+ /* Read the coefficients, inputs and perform multiply-accumulate */
+ c2 = *(ptr2 + S->L * 2);
+
+ xa = vextq_f32(x0v,x1v,2);
+ xb = vextq_f32(x1v,x2v,2);
+
+ accV0 = vmlaq_n_f32(accV0,xa,c2);
+ accV1 = vmlaq_n_f32(accV1,xb,c2);
+
+ /* Read the coefficients, inputs and perform multiply-accumulate */
+ c3 = *(ptr2 + S->L * 3);
+
+ xa = vextq_f32(x0v,x1v,3);
+ xb = vextq_f32(x1v,x2v,3);
+
+ accV0 = vmlaq_n_f32(accV0,xa,c3);
+ accV1 = vmlaq_n_f32(accV1,xb,c3);
+
+ /* Upsampling is done by stuffing L-1 zeros between each sample.
+ * So instead of multiplying zeros with coefficients,
+ * Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += 4 * S->L;
+ ptr1 += 4;
+ x0v = x1v;
+ x1v = x2v;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
+ tapCnt = phaseLen % 0x4U;
+
+ x2v = vld1q_f32(ptr1 + 8);
+
+ switch (tapCnt)
+ {
+ case 3:
+ c0 = *(ptr2);
+ accV0 = vmlaq_n_f32(accV0,x0v,c0);
+ accV1 = vmlaq_n_f32(accV1,x1v,c0);
+ ptr2 += S->L;
+
+ c0 = *(ptr2);
+
+ xa = vextq_f32(x0v,x1v,1);
+ xb = vextq_f32(x1v,x2v,1);
+
+ accV0 = vmlaq_n_f32(accV0,xa,c0);
+ accV1 = vmlaq_n_f32(accV1,xb,c0);
+ ptr2 += S->L;
+
+ c0 = *(ptr2);
+
+ xa = vextq_f32(x0v,x1v,2);
+ xb = vextq_f32(x1v,x2v,2);
+
+ accV0 = vmlaq_n_f32(accV0,xa,c0);
+ accV1 = vmlaq_n_f32(accV1,xb,c0);
+ ptr2 += S->L;
+
+ break;
+
+ case 2:
+ c0 = *(ptr2);
+ accV0 = vmlaq_n_f32(accV0,x0v,c0);
+ accV1 = vmlaq_n_f32(accV1,x1v,c0);
+ ptr2 += S->L;
+
+ c0 = *(ptr2);
+
+ xa = vextq_f32(x0v,x1v,1);
+ xb = vextq_f32(x1v,x2v,1);
+
+ accV0 = vmlaq_n_f32(accV0,xa,c0);
+ accV1 = vmlaq_n_f32(accV1,xb,c0);
+ ptr2 += S->L;
+
+ break;
+
+ case 1:
+ c0 = *(ptr2);
+ accV0 = vmlaq_n_f32(accV0,x0v,c0);
+ accV1 = vmlaq_n_f32(accV1,x1v,c0);
+ ptr2 += S->L;
+
+ break;
+
+ default:
+ break;
+
+ }
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *pDst = accV0[0];
+ *(pDst + S->L) = accV0[1];
+ *(pDst + 2 * S->L) = accV0[2];
+ *(pDst + 3 * S->L) = accV0[3];
+
+ *(pDst + 4 * S->L) = accV1[0];
+ *(pDst + 5 * S->L) = accV1[1];
+ *(pDst + 6 * S->L) = accV1[2];
+ *(pDst + 7 * S->L) = accV1[3];
+
+ pDst++;
+
+ /* Increment the address modifier index of coefficient buffer */
+ j++;
+
+ /* Decrement the loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 1
+ * to process the next group of interpolation factor number samples */
+ pState = pState + 8;
+
+ pDst += S->L * 7;
+
+ /* 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. */
+
+ while (blkCntN4 > 0U)
+ {
+ /* Copy new input sample into the state buffer */
+ *pStateCurnt++ = *pSrc++;
+
+ /* Address modifier index of coefficient buffer */
+ j = 1U;
+
+ /* Loop over the Interpolation factor. */
+ i = S->L;
+
+ while (i > 0U)
+ {
+ /* Set accumulator to zero */
+ sum0v = vdupq_n_f32(0.0);
+
+ /* Initialize state pointer */
+ ptr1 = pState;
+
+ /* Initialize coefficient pointer */
+ ptr2 = pCoeffs + (S->L - j);
+
+ /* Loop over the polyPhase length. Unroll by a factor of 4.
+ ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
+ tapCnt = phaseLen >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ /* Read the coefficient */
+ x1v[0] = *(ptr2);
+
+ /* Upsampling is done by stuffing L-1 zeros between each sample.
+ * So instead of multiplying zeros with coefficients,
+ * Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* Read the input sample */
+ x0v = vld1q_f32(ptr1);
+ ptr1 += 4;
+
+ /* Read the coefficient */
+ x1v[1] = *(ptr2);
+
+ /* Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* Read the coefficient */
+ x1v[2] = *(ptr2);
+
+ /* Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* Read the coefficient */
+ x1v[3] = *(ptr2);
+
+ /* Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ sum0v = vmlaq_f32(sum0v,x0v,x1v);
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ tempV = vpadd_f32(vget_low_f32(sum0v),vget_high_f32(sum0v));
+ sum0 = tempV[0] + tempV[1];
+
+ /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
+ tapCnt = phaseLen % 0x4U;
+
+ while (tapCnt > 0U)
+ {
+ /* Perform the multiply-accumulate */
+ sum0 += *(ptr1++) * (*ptr2);
+
+ /* Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *pDst++ = sum0;
+
+ /* Increment the address modifier index of coefficient buffer */
+ j++;
+
+ /* Decrement the loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 1
+ * to process the next group of interpolation factor number samples */
+ pState = pState + 1;
+
+ /* Decrement the loop counter */
+ blkCntN4--;
+ }
+
+ /* Processing is complete.
+ ** Now copy the last phaseLen - 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;
+
+ tapCnt = (phaseLen - 1U) >> 2U;
+
+ /* Copy data */
+ while (tapCnt > 0U)
+ {
+ sum0v = vld1q_f32(pState);
+ vst1q_f32(pStateCurnt,sum0v);
+ pState += 4;
+ pStateCurnt += 4;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ tapCnt = (phaseLen - 1U) % 0x04U;
+
+ /* copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+}
+#else
+
+void arm_fir_interpolate_f32(
+ const arm_fir_interpolate_instance_f32 * S,
+ const float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+#if (1)
+//#if !defined(ARM_MATH_CM0_FAMILY)
+
+ 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 *ptr1; /* Temporary pointer for state buffer */
+ const float32_t *ptr2; /* Temporary pointer for coefficient buffer */
+ float32_t sum0; /* Accumulators */
+ uint32_t i, blkCnt, tapCnt; /* Loop counters */
+ uint32_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */
+ uint32_t j;
+
+#if defined (ARM_MATH_LOOPUNROLL)
+ float32_t acc0, acc1, acc2, acc3;
+ float32_t x0, x1, x2, x3;
+ float32_t c0, c1, c2, c3;
+#endif
+
+ /* S->pState buffer contains previous frame (phaseLen - 1) samples */
+ /* pStateCur points to the location where the new input data should be written */
+ pStateCur = S->pState + (phaseLen - 1U);
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 outputs at a time */
+ blkCnt = blockSize >> 2U;
+
+ while (blkCnt > 0U)
+ {
+ /* Copy new input sample into the state buffer */
+ *pStateCur++ = *pSrc++;
+ *pStateCur++ = *pSrc++;
+ *pStateCur++ = *pSrc++;
+ *pStateCur++ = *pSrc++;
+
+ /* Address modifier index of coefficient buffer */
+ j = 1U;
+
+ /* Loop over the Interpolation factor. */
+ i = (S->L);
+
+ while (i > 0U)
+ {
+ /* Set accumulator to zero */
+ acc0 = 0.0f;
+ acc1 = 0.0f;
+ acc2 = 0.0f;
+ acc3 = 0.0f;
+
+ /* Initialize state pointer */
+ ptr1 = pState;
+
+ /* Initialize coefficient pointer */
+ ptr2 = pCoeffs + (S->L - j);
+
+ /* Loop over the polyPhase length. Unroll by a factor of 4.
+ Repeat until we've computed numTaps-(4*S->L) coefficients. */
+ tapCnt = phaseLen >> 2U;
+
+ x0 = *(ptr1++);
+ x1 = *(ptr1++);
+ x2 = *(ptr1++);
+
+ while (tapCnt > 0U)
+ {
+ /* Read the input sample */
+ x3 = *(ptr1++);
+
+ /* Read the coefficient */
+ c0 = *(ptr2);
+
+ /* Perform the multiply-accumulate */
+ acc0 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* Read the coefficient */
+ c1 = *(ptr2 + S->L);
+
+ /* Read the input sample */
+ x0 = *(ptr1++);
+
+ /* Perform the multiply-accumulate */
+ acc0 += x1 * c1;
+ acc1 += x2 * c1;
+ acc2 += x3 * c1;
+ acc3 += x0 * c1;
+
+ /* Read the coefficient */
+ c2 = *(ptr2 + S->L * 2);
+
+ /* Read the input sample */
+ x1 = *(ptr1++);
+
+ /* Perform the multiply-accumulate */
+ acc0 += x2 * c2;
+ acc1 += x3 * c2;
+ acc2 += x0 * c2;
+ acc3 += x1 * c2;
+
+ /* Read the coefficient */
+ c3 = *(ptr2 + S->L * 3);
+
+ /* Read the input sample */
+ x2 = *(ptr1++);
+
+ /* Perform the multiply-accumulate */
+ acc0 += x3 * c3;
+ acc1 += x0 * c3;
+ acc2 += x1 * c3;
+ acc3 += x2 * c3;
+
+
+ /* Upsampling is done by stuffing L-1 zeros between each sample.
+ * So instead of multiplying zeros with coefficients,
+ * Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += 4 * S->L;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
+ tapCnt = phaseLen % 0x4U;
+
+ while (tapCnt > 0U)
+ {
+ /* Read the input sample */
+ x3 = *(ptr1++);
+
+ /* Read the coefficient */
+ c0 = *(ptr2);
+
+ /* Perform the multiply-accumulate */
+ acc0 += x0 * c0;
+ acc1 += x1 * c0;
+ acc2 += x2 * c0;
+ acc3 += x3 * c0;
+
+ /* Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* update states for next sample processing */
+ x0 = x1;
+ x1 = x2;
+ x2 = x3;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *(pDst ) = acc0;
+ *(pDst + S->L) = acc1;
+ *(pDst + 2 * S->L) = acc2;
+ *(pDst + 3 * S->L) = acc3;
+
+ pDst++;
+
+ /* Increment the address modifier index of coefficient buffer */
+ j++;
+
+ /* Decrement loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 1
+ * to process the next group of interpolation factor number samples */
+ pState = pState + 4;
+
+ pDst += S->L * 3;
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining outputs */
+ blkCnt = blockSize % 0x4U;
+
+#else
+
+ /* Initialize blkCnt with number of samples */
+ blkCnt = blockSize;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (blkCnt > 0U)
+ {
+ /* Copy new input sample into the state buffer */
+ *pStateCur++ = *pSrc++;
+
+ /* Address modifier index of coefficient buffer */
+ j = 1U;
+
+ /* Loop over the Interpolation factor. */
+ i = S->L;
+
+ while (i > 0U)
+ {
+ /* Set accumulator to zero */
+ sum0 = 0.0f;
+
+ /* Initialize state pointer */
+ ptr1 = pState;
+
+ /* Initialize coefficient pointer */
+ ptr2 = pCoeffs + (S->L - j);
+
+ /* Loop over the polyPhase length.
+ Repeat until we've computed numTaps-(4*S->L) coefficients. */
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 outputs at a time */
+ tapCnt = phaseLen >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ /* Perform the multiply-accumulate */
+ sum0 += *ptr1++ * *ptr2;
+
+ /* Upsampling is done by stuffing L-1 zeros between each sample.
+ * So instead of multiplying zeros with coefficients,
+ * Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ sum0 += *ptr1++ * *ptr2;
+ ptr2 += S->L;
+
+ sum0 += *ptr1++ * *ptr2;
+ ptr2 += S->L;
+
+ sum0 += *ptr1++ * *ptr2;
+ ptr2 += S->L;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining outputs */
+ tapCnt = phaseLen % 0x4U;
+
+#else
+
+ /* Initialize tapCnt with number of samples */
+ tapCnt = phaseLen;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (tapCnt > 0U)
+ {
+ /* Perform the multiply-accumulate */
+ sum0 += *ptr1++ * *ptr2;
+
+ /* Upsampling is done by stuffing L-1 zeros between each sample.
+ * So instead of multiplying zeros with coefficients,
+ * Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *pDst++ = sum0;
+
+ /* Increment the address modifier index of coefficient buffer */
+ j++;
+
+ /* Decrement the loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 1
+ * to process the next group of interpolation factor number samples */
+ pState = pState + 1;
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete.
+ Now copy the last phaseLen - 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 outputs at a time */
+ tapCnt = (phaseLen - 1U) >> 2U;
+
+ /* copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining outputs */
+ tapCnt = (phaseLen - 1U) % 0x04U;
+
+#else
+
+ /* Initialize tapCnt with number of samples */
+ tapCnt = (phaseLen - 1U);
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ /* Copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+#else
+/* alternate version for CM0_FAMILY */
+
+ 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 *ptr1; /* Temporary pointer for state buffer */
+ const float32_t *ptr2; /* Temporary pointer for coefficient buffer */
+ float32_t sum0; /* Accumulators */
+ uint32_t i, blkCnt, tapCnt; /* Loop counters */
+ uint32_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */
+
+ /* S->pState buffer contains previous frame (phaseLen - 1) samples */
+ /* pStateCur points to the location where the new input data should be written */
+ pStateCur = S->pState + (phaseLen - 1U);
+
+ /* Total number of intput samples */
+ blkCnt = blockSize;
+
+ /* Loop over the blockSize. */
+ while (blkCnt > 0U)
+ {
+ /* Copy new input sample into the state buffer */
+ *pStateCur++ = *pSrc++;
+
+ /* Loop over the Interpolation factor. */
+ i = S->L;
+
+ while (i > 0U)
+ {
+ /* Set accumulator to zero */
+ sum0 = 0.0f;
+
+ /* Initialize state pointer */
+ ptr1 = pState;
+
+ /* Initialize coefficient pointer */
+ ptr2 = pCoeffs + (i - 1U);
+
+ /* Loop over the polyPhase length */
+ tapCnt = phaseLen;
+
+ while (tapCnt > 0U)
+ {
+ /* Perform the multiply-accumulate */
+ sum0 += *ptr1++ * *ptr2;
+
+ /* Increment the coefficient pointer by interpolation factor times. */
+ ptr2 += S->L;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ /* The result is in the accumulator, store in the destination buffer. */
+ *pDst++ = sum0;
+
+ /* Decrement loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 1
+ * to process the next group of interpolation factor number samples */
+ pState = pState + 1;
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete.
+ ** Now copy the last phaseLen - 1 samples to the start 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;
+
+ tapCnt = phaseLen - 1U;
+
+ /* Copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+#endif /* #if !defined(ARM_MATH_CM0_FAMILY) */
+
+}
+
+#endif /* #if defined(ARM_MATH_NEON) */
+
+/**
+ @} end of FIR_Interpolate group
+ */
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