| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_biquad_cascade_stereo_df2T_f32.c |
| * Description: Processing function for floating-point transposed direct form II Biquad cascade filter. 2 channels |
| * |
| * $Date: 27. January 2017 |
| * $Revision: V.1.5.1 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2017 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 BiquadCascadeDF2T Biquad Cascade IIR Filters Using a Direct Form II Transposed Structure |
| * |
| * This set of functions implements arbitrary order recursive (IIR) filters using a transposed direct form II structure. |
| * The filters are implemented as a cascade of second order Biquad sections. |
| * These functions provide a slight memory savings as compared to the direct form I Biquad filter functions. |
| * Only floating-point data is supported. |
| * |
| * This function operate on blocks of input and output data and each call to the function |
| * processes <code>blockSize</code> samples through the filter. |
| * <code>pSrc</code> points to the array of input data and |
| * <code>pDst</code> points to the array of output data. |
| * Both arrays contain <code>blockSize</code> values. |
| * |
| * \par Algorithm |
| * Each Biquad stage implements a second order filter using the difference equation: |
| * <pre> |
| * y[n] = b0 * x[n] + d1 |
| * d1 = b1 * x[n] + a1 * y[n] + d2 |
| * d2 = b2 * x[n] + a2 * y[n] |
| * </pre> |
| * where d1 and d2 represent the two state values. |
| * |
| * \par |
| * A Biquad filter using a transposed Direct Form II structure is shown below. |
| * \image html BiquadDF2Transposed.gif "Single transposed Direct Form II Biquad" |
| * Coefficients <code>b0, b1, and b2 </code> multiply the input signal <code>x[n]</code> and are referred to as the feedforward coefficients. |
| * Coefficients <code>a1</code> and <code>a2</code> multiply the output signal <code>y[n]</code> and are referred to as the feedback coefficients. |
| * Pay careful attention to the sign of the feedback coefficients. |
| * Some design tools flip the sign of the feedback coefficients: |
| * <pre> |
| * y[n] = b0 * x[n] + d1; |
| * d1 = b1 * x[n] - a1 * y[n] + d2; |
| * d2 = b2 * x[n] - a2 * y[n]; |
| * </pre> |
| * In this case the feedback coefficients <code>a1</code> and <code>a2</code> must be negated when used with the CMSIS DSP Library. |
| * |
| * \par |
| * Higher order filters are realized as a cascade of second order sections. |
| * <code>numStages</code> refers to the number of second order stages used. |
| * For example, an 8th order filter would be realized with <code>numStages=4</code> second order stages. |
| * A 9th order filter would be realized with <code>numStages=5</code> second order stages with the |
| * coefficients for one of the stages configured as a first order filter (<code>b2=0</code> and <code>a2=0</code>). |
| * |
| * \par |
| * <code>pState</code> points to the state variable array. |
| * Each Biquad stage has 2 state variables <code>d1</code> and <code>d2</code>. |
| * The state variables are arranged in the <code>pState</code> array as: |
| * <pre> |
| * {d11, d12, d21, d22, ...} |
| * </pre> |
| * where <code>d1x</code> refers to the state variables for the first Biquad and |
| * <code>d2x</code> refers to the state variables for the second Biquad. |
| * The state array has a total length of <code>2*numStages</code> values. |
| * The state variables are updated after each block of data is processed; the coefficients are untouched. |
| * |
| * \par |
| * The CMSIS library contains Biquad filters in both Direct Form I and transposed Direct Form II. |
| * The advantage of the Direct Form I structure is that it is numerically more robust for fixed-point data types. |
| * That is why the Direct Form I structure supports Q15 and Q31 data types. |
| * The transposed Direct Form II structure, on the other hand, requires a wide dynamic range for the state variables <code>d1</code> and <code>d2</code>. |
| * Because of this, the CMSIS library only has a floating-point version of the Direct Form II Biquad. |
| * The advantage of the Direct Form II Biquad is that it requires half the number of state variables, 2 rather than 4, per Biquad stage. |
| * |
| * \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 arrays cannot be shared. |
| * |
| * \par Init Functions |
| * There is also an associated initialization function. |
| * The initialization function performs following operations: |
| * - Sets the values of the internal structure fields. |
| * - Zeros out the values in the state buffer. |
| * To do this manually without calling the init function, assign the follow subfields of the instance structure: |
| * numStages, pCoeffs, 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. |
| * Set the values in the state buffer to zeros before static initialization. |
| * For example, to statically initialize the instance structure use |
| * <pre> |
| * arm_biquad_cascade_df2T_instance_f32 S1 = {numStages, pState, pCoeffs}; |
| * </pre> |
| * where <code>numStages</code> is the number of Biquad stages in the filter; <code>pState</code> is the address of the state buffer. |
| * <code>pCoeffs</code> is the address of the coefficient buffer; |
| * |
| */ |
| |
| /** |
| * @addtogroup BiquadCascadeDF2T |
| * @{ |
| */ |
| |
| /** |
| * @brief Processing function for the floating-point transposed direct form II Biquad cascade filter. |
| * @param[in] *S points to an instance of the filter data 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. |
| */ |
| |
| |
| LOW_OPTIMIZATION_ENTER |
| void arm_biquad_cascade_stereo_df2T_f32( |
| const arm_biquad_cascade_stereo_df2T_instance_f32 * S, |
| float32_t * pSrc, |
| float32_t * pDst, |
| uint32_t blockSize) |
| { |
| |
| float32_t *pIn = pSrc; /* source pointer */ |
| float32_t *pOut = pDst; /* destination pointer */ |
| float32_t *pState = S->pState; /* State pointer */ |
| float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */ |
| float32_t acc1a, acc1b; /* accumulator */ |
| float32_t b0, b1, b2, a1, a2; /* Filter coefficients */ |
| float32_t Xn1a, Xn1b; /* temporary input */ |
| float32_t d1a, d2a, d1b, d2b; /* state variables */ |
| uint32_t sample, stage = S->numStages; /* loop counters */ |
| |
| #if defined(ARM_MATH_CM7) |
| |
| float32_t Xn2a, Xn3a, Xn4a, Xn5a, Xn6a, Xn7a, Xn8a; /* Input State variables */ |
| float32_t Xn2b, Xn3b, Xn4b, Xn5b, Xn6b, Xn7b, Xn8b; /* Input State variables */ |
| float32_t acc2a, acc3a, acc4a, acc5a, acc6a, acc7a, acc8a; /* Simulates the accumulator */ |
| float32_t acc2b, acc3b, acc4b, acc5b, acc6b, acc7b, acc8b; /* Simulates the accumulator */ |
| |
| do |
| { |
| /* Reading the coefficients */ |
| b0 = pCoeffs[0]; |
| b1 = pCoeffs[1]; |
| b2 = pCoeffs[2]; |
| a1 = pCoeffs[3]; |
| /* Apply loop unrolling and compute 8 output values simultaneously. */ |
| sample = blockSize >> 3U; |
| a2 = pCoeffs[4]; |
| |
| /*Reading the state values */ |
| d1a = pState[0]; |
| d2a = pState[1]; |
| d1b = pState[2]; |
| d2b = pState[3]; |
| |
| pCoeffs += 5U; |
| |
| /* First part of the processing with loop unrolling. Compute 8 outputs at a time. |
| ** a second loop below computes the remaining 1 to 7 samples. */ |
| while (sample > 0U) { |
| |
| /* y[n] = b0 * x[n] + d1 */ |
| /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
| /* d2 = b2 * x[n] + a2 * y[n] */ |
| |
| /* Read the first 2 inputs. 2 cycles */ |
| Xn1a = pIn[0 ]; |
| Xn1b = pIn[1 ]; |
| |
| /* Sample 1. 5 cycles */ |
| Xn2a = pIn[2 ]; |
| acc1a = b0 * Xn1a + d1a; |
| |
| Xn2b = pIn[3 ]; |
| d1a = b1 * Xn1a + d2a; |
| |
| Xn3a = pIn[4 ]; |
| d2a = b2 * Xn1a; |
| |
| Xn3b = pIn[5 ]; |
| d1a += a1 * acc1a; |
| |
| Xn4a = pIn[6 ]; |
| d2a += a2 * acc1a; |
| |
| /* Sample 2. 5 cycles */ |
| Xn4b = pIn[7 ]; |
| acc1b = b0 * Xn1b + d1b; |
| |
| Xn5a = pIn[8 ]; |
| d1b = b1 * Xn1b + d2b; |
| |
| Xn5b = pIn[9 ]; |
| d2b = b2 * Xn1b; |
| |
| Xn6a = pIn[10]; |
| d1b += a1 * acc1b; |
| |
| Xn6b = pIn[11]; |
| d2b += a2 * acc1b; |
| |
| /* Sample 3. 5 cycles */ |
| Xn7a = pIn[12]; |
| acc2a = b0 * Xn2a + d1a; |
| |
| Xn7b = pIn[13]; |
| d1a = b1 * Xn2a + d2a; |
| |
| Xn8a = pIn[14]; |
| d2a = b2 * Xn2a; |
| |
| Xn8b = pIn[15]; |
| d1a += a1 * acc2a; |
| |
| pIn += 16; |
| d2a += a2 * acc2a; |
| |
| /* Sample 4. 5 cycles */ |
| acc2b = b0 * Xn2b + d1b; |
| d1b = b1 * Xn2b + d2b; |
| d2b = b2 * Xn2b; |
| d1b += a1 * acc2b; |
| d2b += a2 * acc2b; |
| |
| /* Sample 5. 5 cycles */ |
| acc3a = b0 * Xn3a + d1a; |
| d1a = b1 * Xn3a + d2a; |
| d2a = b2 * Xn3a; |
| d1a += a1 * acc3a; |
| d2a += a2 * acc3a; |
| |
| /* Sample 6. 5 cycles */ |
| acc3b = b0 * Xn3b + d1b; |
| d1b = b1 * Xn3b + d2b; |
| d2b = b2 * Xn3b; |
| d1b += a1 * acc3b; |
| d2b += a2 * acc3b; |
| |
| /* Sample 7. 5 cycles */ |
| acc4a = b0 * Xn4a + d1a; |
| d1a = b1 * Xn4a + d2a; |
| d2a = b2 * Xn4a; |
| d1a += a1 * acc4a; |
| d2a += a2 * acc4a; |
| |
| /* Sample 8. 5 cycles */ |
| acc4b = b0 * Xn4b + d1b; |
| d1b = b1 * Xn4b + d2b; |
| d2b = b2 * Xn4b; |
| d1b += a1 * acc4b; |
| d2b += a2 * acc4b; |
| |
| /* Sample 9. 5 cycles */ |
| acc5a = b0 * Xn5a + d1a; |
| d1a = b1 * Xn5a + d2a; |
| d2a = b2 * Xn5a; |
| d1a += a1 * acc5a; |
| d2a += a2 * acc5a; |
| |
| /* Sample 10. 5 cycles */ |
| acc5b = b0 * Xn5b + d1b; |
| d1b = b1 * Xn5b + d2b; |
| d2b = b2 * Xn5b; |
| d1b += a1 * acc5b; |
| d2b += a2 * acc5b; |
| |
| /* Sample 11. 5 cycles */ |
| acc6a = b0 * Xn6a + d1a; |
| d1a = b1 * Xn6a + d2a; |
| d2a = b2 * Xn6a; |
| d1a += a1 * acc6a; |
| d2a += a2 * acc6a; |
| |
| /* Sample 12. 5 cycles */ |
| acc6b = b0 * Xn6b + d1b; |
| d1b = b1 * Xn6b + d2b; |
| d2b = b2 * Xn6b; |
| d1b += a1 * acc6b; |
| d2b += a2 * acc6b; |
| |
| /* Sample 13. 5 cycles */ |
| acc7a = b0 * Xn7a + d1a; |
| d1a = b1 * Xn7a + d2a; |
| |
| pOut[0 ] = acc1a ; |
| d2a = b2 * Xn7a; |
| |
| pOut[1 ] = acc1b ; |
| d1a += a1 * acc7a; |
| |
| pOut[2 ] = acc2a ; |
| d2a += a2 * acc7a; |
| |
| /* Sample 14. 5 cycles */ |
| pOut[3 ] = acc2b ; |
| acc7b = b0 * Xn7b + d1b; |
| |
| pOut[4 ] = acc3a ; |
| d1b = b1 * Xn7b + d2b; |
| |
| pOut[5 ] = acc3b ; |
| d2b = b2 * Xn7b; |
| |
| pOut[6 ] = acc4a ; |
| d1b += a1 * acc7b; |
| |
| pOut[7 ] = acc4b ; |
| d2b += a2 * acc7b; |
| |
| /* Sample 15. 5 cycles */ |
| pOut[8 ] = acc5a ; |
| acc8a = b0 * Xn8a + d1a; |
| |
| pOut[9 ] = acc5b; |
| d1a = b1 * Xn8a + d2a; |
| |
| pOut[10] = acc6a; |
| d2a = b2 * Xn8a; |
| |
| pOut[11] = acc6b; |
| d1a += a1 * acc8a; |
| |
| pOut[12] = acc7a; |
| d2a += a2 * acc8a; |
| |
| /* Sample 16. 5 cycles */ |
| pOut[13] = acc7b; |
| acc8b = b0 * Xn8b + d1b; |
| |
| pOut[14] = acc8a; |
| d1b = b1 * Xn8b + d2b; |
| |
| pOut[15] = acc8b; |
| d2b = b2 * Xn8b; |
| |
| sample--; |
| d1b += a1 * acc8b; |
| |
| pOut += 16; |
| d2b += a2 * acc8b; |
| } |
| |
| sample = blockSize & 0x7U; |
| while (sample > 0U) { |
| /* Read the input */ |
| Xn1a = *pIn++; //Channel a |
| Xn1b = *pIn++; //Channel b |
| |
| /* y[n] = b0 * x[n] + d1 */ |
| acc1a = (b0 * Xn1a) + d1a; |
| acc1b = (b0 * Xn1b) + d1b; |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut++ = acc1a; |
| *pOut++ = acc1b; |
| |
| /* Every time after the output is computed state should be updated. */ |
| /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
| d1a = ((b1 * Xn1a) + (a1 * acc1a)) + d2a; |
| d1b = ((b1 * Xn1b) + (a1 * acc1b)) + d2b; |
| |
| /* d2 = b2 * x[n] + a2 * y[n] */ |
| d2a = (b2 * Xn1a) + (a2 * acc1a); |
| d2b = (b2 * Xn1b) + (a2 * acc1b); |
| |
| sample--; |
| } |
| |
| /* Store the updated state variables back into the state array */ |
| pState[0] = d1a; |
| pState[1] = d2a; |
| |
| pState[2] = d1b; |
| pState[3] = d2b; |
| |
| /* The current stage input is given as the output to the next stage */ |
| pIn = pDst; |
| /* decrement the loop counter */ |
| stage--; |
| |
| pState += 4U; |
| /*Reset the output working pointer */ |
| pOut = pDst; |
| |
| } while (stage > 0U); |
| |
| #elif defined(ARM_MATH_CM0_FAMILY) |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| do |
| { |
| /* Reading the coefficients */ |
| b0 = *pCoeffs++; |
| b1 = *pCoeffs++; |
| b2 = *pCoeffs++; |
| a1 = *pCoeffs++; |
| a2 = *pCoeffs++; |
| |
| /*Reading the state values */ |
| d1a = pState[0]; |
| d2a = pState[1]; |
| d1b = pState[2]; |
| d2b = pState[3]; |
| |
| |
| sample = blockSize; |
| |
| while (sample > 0U) |
| { |
| /* Read the input */ |
| Xn1a = *pIn++; //Channel a |
| Xn1b = *pIn++; //Channel b |
| |
| /* y[n] = b0 * x[n] + d1 */ |
| acc1a = (b0 * Xn1a) + d1a; |
| acc1b = (b0 * Xn1b) + d1b; |
| |
| /* Store the result in the accumulator in the destination buffer. */ |
| *pOut++ = acc1a; |
| *pOut++ = acc1b; |
| |
| /* Every time after the output is computed state should be updated. */ |
| /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
| d1a = ((b1 * Xn1a) + (a1 * acc1a)) + d2a; |
| d1b = ((b1 * Xn1b) + (a1 * acc1b)) + d2b; |
| |
| /* d2 = b2 * x[n] + a2 * y[n] */ |
| d2a = (b2 * Xn1a) + (a2 * acc1a); |
| d2b = (b2 * Xn1b) + (a2 * acc1b); |
| |
| /* decrement the loop counter */ |
| sample--; |
| } |
| |
| /* Store the updated state variables back into the state array */ |
| *pState++ = d1a; |
| *pState++ = d2a; |
| *pState++ = d1b; |
| *pState++ = d2b; |
| |
| /* The current stage input is given as the output to the next stage */ |
| pIn = pDst; |
| |
| /*Reset the output working pointer */ |
| pOut = pDst; |
| |
| /* decrement the loop counter */ |
| stage--; |
| |
| } while (stage > 0U); |
| |
| #else |
| |
| float32_t Xn2a, Xn3a, Xn4a; /* Input State variables */ |
| float32_t Xn2b, Xn3b, Xn4b; /* Input State variables */ |
| float32_t acc2a, acc3a, acc4a; /* accumulator */ |
| float32_t acc2b, acc3b, acc4b; /* accumulator */ |
| float32_t p0a, p1a, p2a, p3a, p4a, A1a; |
| float32_t p0b, p1b, p2b, p3b, p4b, A1b; |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| do |
| { |
| /* Reading the coefficients */ |
| b0 = *pCoeffs++; |
| b1 = *pCoeffs++; |
| b2 = *pCoeffs++; |
| a1 = *pCoeffs++; |
| a2 = *pCoeffs++; |
| |
| /*Reading the state values */ |
| d1a = pState[0]; |
| d2a = pState[1]; |
| d1b = pState[2]; |
| d2b = pState[3]; |
| |
| /* Apply loop unrolling and compute 4 output values simultaneously. */ |
| sample = blockSize >> 2U; |
| |
| /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
| ** a second loop below computes the remaining 1 to 3 samples. */ |
| while (sample > 0U) { |
| |
| /* y[n] = b0 * x[n] + d1 */ |
| /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
| /* d2 = b2 * x[n] + a2 * y[n] */ |
| |
| /* Read the four inputs */ |
| Xn1a = pIn[0]; |
| Xn1b = pIn[1]; |
| Xn2a = pIn[2]; |
| Xn2b = pIn[3]; |
| Xn3a = pIn[4]; |
| Xn3b = pIn[5]; |
| Xn4a = pIn[6]; |
| Xn4b = pIn[7]; |
| pIn += 8; |
| |
| p0a = b0 * Xn1a; |
| p0b = b0 * Xn1b; |
| p1a = b1 * Xn1a; |
| p1b = b1 * Xn1b; |
| acc1a = p0a + d1a; |
| acc1b = p0b + d1b; |
| p0a = b0 * Xn2a; |
| p0b = b0 * Xn2b; |
| p3a = a1 * acc1a; |
| p3b = a1 * acc1b; |
| p2a = b2 * Xn1a; |
| p2b = b2 * Xn1b; |
| A1a = p1a + p3a; |
| A1b = p1b + p3b; |
| p4a = a2 * acc1a; |
| p4b = a2 * acc1b; |
| d1a = A1a + d2a; |
| d1b = A1b + d2b; |
| d2a = p2a + p4a; |
| d2b = p2b + p4b; |
| |
| p1a = b1 * Xn2a; |
| p1b = b1 * Xn2b; |
| acc2a = p0a + d1a; |
| acc2b = p0b + d1b; |
| p0a = b0 * Xn3a; |
| p0b = b0 * Xn3b; |
| p3a = a1 * acc2a; |
| p3b = a1 * acc2b; |
| p2a = b2 * Xn2a; |
| p2b = b2 * Xn2b; |
| A1a = p1a + p3a; |
| A1b = p1b + p3b; |
| p4a = a2 * acc2a; |
| p4b = a2 * acc2b; |
| d1a = A1a + d2a; |
| d1b = A1b + d2b; |
| d2a = p2a + p4a; |
| d2b = p2b + p4b; |
| |
| p1a = b1 * Xn3a; |
| p1b = b1 * Xn3b; |
| acc3a = p0a + d1a; |
| acc3b = p0b + d1b; |
| p0a = b0 * Xn4a; |
| p0b = b0 * Xn4b; |
| p3a = a1 * acc3a; |
| p3b = a1 * acc3b; |
| p2a = b2 * Xn3a; |
| p2b = b2 * Xn3b; |
| A1a = p1a + p3a; |
| A1b = p1b + p3b; |
| p4a = a2 * acc3a; |
| p4b = a2 * acc3b; |
| d1a = A1a + d2a; |
| d1b = A1b + d2b; |
| d2a = p2a + p4a; |
| d2b = p2b + p4b; |
| |
| acc4a = p0a + d1a; |
| acc4b = p0b + d1b; |
| p1a = b1 * Xn4a; |
| p1b = b1 * Xn4b; |
| p3a = a1 * acc4a; |
| p3b = a1 * acc4b; |
| p2a = b2 * Xn4a; |
| p2b = b2 * Xn4b; |
| A1a = p1a + p3a; |
| A1b = p1b + p3b; |
| p4a = a2 * acc4a; |
| p4b = a2 * acc4b; |
| d1a = A1a + d2a; |
| d1b = A1b + d2b; |
| d2a = p2a + p4a; |
| d2b = p2b + p4b; |
| |
| pOut[0] = acc1a; |
| pOut[1] = acc1b; |
| pOut[2] = acc2a; |
| pOut[3] = acc2b; |
| pOut[4] = acc3a; |
| pOut[5] = acc3b; |
| pOut[6] = acc4a; |
| pOut[7] = acc4b; |
| pOut += 8; |
| |
| sample--; |
| } |
| |
| sample = blockSize & 0x3U; |
| while (sample > 0U) { |
| Xn1a = *pIn++; |
| Xn1b = *pIn++; |
| |
| p0a = b0 * Xn1a; |
| p0b = b0 * Xn1b; |
| p1a = b1 * Xn1a; |
| p1b = b1 * Xn1b; |
| acc1a = p0a + d1a; |
| acc1b = p0b + d1b; |
| p3a = a1 * acc1a; |
| p3b = a1 * acc1b; |
| p2a = b2 * Xn1a; |
| p2b = b2 * Xn1b; |
| A1a = p1a + p3a; |
| A1b = p1b + p3b; |
| p4a = a2 * acc1a; |
| p4b = a2 * acc1b; |
| d1a = A1a + d2a; |
| d1b = A1b + d2b; |
| d2a = p2a + p4a; |
| d2b = p2b + p4b; |
| |
| *pOut++ = acc1a; |
| *pOut++ = acc1b; |
| |
| sample--; |
| } |
| |
| /* Store the updated state variables back into the state array */ |
| *pState++ = d1a; |
| *pState++ = d2a; |
| *pState++ = d1b; |
| *pState++ = d2b; |
| |
| /* The current stage input is given as the output to the next stage */ |
| pIn = pDst; |
| |
| /*Reset the output working pointer */ |
| pOut = pDst; |
| |
| /* decrement the loop counter */ |
| stage--; |
| |
| } while (stage > 0U); |
| |
| #endif |
| |
| } |
| LOW_OPTIMIZATION_EXIT |
| |
| /** |
| * @} end of BiquadCascadeDF2T group |
| */ |
