| /* ---------------------------------------------------------------------- |
| * 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 |
| */ |
