CMSIS DSP library
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cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df2T_f32.c@2:da51fb522205, 2013-05-30 (annotated)
- Committer:
- emilmont
- Date:
- Thu May 30 17:10:11 2013 +0100
- Revision:
- 2:da51fb522205
- Parent:
- 1:fdd22bb7aa52
- Child:
- 3:7a284390b0ce
Keep "cmsis-dsp" module in synch with its source
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
emilmont | 1:fdd22bb7aa52 | 1 | /* ---------------------------------------------------------------------- |
emilmont | 1:fdd22bb7aa52 | 2 | * Copyright (C) 2010 ARM Limited. All rights reserved. |
emilmont | 1:fdd22bb7aa52 | 3 | * |
emilmont | 1:fdd22bb7aa52 | 4 | * $Date: 15. February 2012 |
emilmont | 2:da51fb522205 | 5 | * $Revision: V1.1.0 |
emilmont | 1:fdd22bb7aa52 | 6 | * |
emilmont | 2:da51fb522205 | 7 | * Project: CMSIS DSP Library |
emilmont | 2:da51fb522205 | 8 | * Title: arm_biquad_cascade_df2T_f32.c |
emilmont | 1:fdd22bb7aa52 | 9 | * |
emilmont | 1:fdd22bb7aa52 | 10 | * Description: Processing function for the floating-point transposed |
emilmont | 1:fdd22bb7aa52 | 11 | * direct form II Biquad cascade filter. |
emilmont | 1:fdd22bb7aa52 | 12 | * |
emilmont | 1:fdd22bb7aa52 | 13 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
emilmont | 1:fdd22bb7aa52 | 14 | * |
emilmont | 1:fdd22bb7aa52 | 15 | * Version 1.1.0 2012/02/15 |
emilmont | 1:fdd22bb7aa52 | 16 | * Updated with more optimizations, bug fixes and minor API changes. |
emilmont | 1:fdd22bb7aa52 | 17 | * |
emilmont | 1:fdd22bb7aa52 | 18 | * Version 1.0.10 2011/7/15 |
emilmont | 1:fdd22bb7aa52 | 19 | * Big Endian support added and Merged M0 and M3/M4 Source code. |
emilmont | 1:fdd22bb7aa52 | 20 | * |
emilmont | 1:fdd22bb7aa52 | 21 | * Version 1.0.3 2010/11/29 |
emilmont | 1:fdd22bb7aa52 | 22 | * Re-organized the CMSIS folders and updated documentation. |
emilmont | 1:fdd22bb7aa52 | 23 | * |
emilmont | 1:fdd22bb7aa52 | 24 | * Version 1.0.2 2010/11/11 |
emilmont | 1:fdd22bb7aa52 | 25 | * Documentation updated. |
emilmont | 1:fdd22bb7aa52 | 26 | * |
emilmont | 1:fdd22bb7aa52 | 27 | * Version 1.0.1 2010/10/05 |
emilmont | 1:fdd22bb7aa52 | 28 | * Production release and review comments incorporated. |
emilmont | 1:fdd22bb7aa52 | 29 | * |
emilmont | 1:fdd22bb7aa52 | 30 | * Version 1.0.0 2010/09/20 |
emilmont | 1:fdd22bb7aa52 | 31 | * Production release and review comments incorporated |
emilmont | 1:fdd22bb7aa52 | 32 | * |
emilmont | 1:fdd22bb7aa52 | 33 | * Version 0.0.7 2010/06/10 |
emilmont | 1:fdd22bb7aa52 | 34 | * Misra-C changes done |
emilmont | 1:fdd22bb7aa52 | 35 | * -------------------------------------------------------------------- */ |
emilmont | 1:fdd22bb7aa52 | 36 | |
emilmont | 1:fdd22bb7aa52 | 37 | #include "arm_math.h" |
emilmont | 1:fdd22bb7aa52 | 38 | |
emilmont | 1:fdd22bb7aa52 | 39 | /** |
emilmont | 1:fdd22bb7aa52 | 40 | * @ingroup groupFilters |
emilmont | 1:fdd22bb7aa52 | 41 | */ |
emilmont | 1:fdd22bb7aa52 | 42 | |
emilmont | 1:fdd22bb7aa52 | 43 | /** |
emilmont | 1:fdd22bb7aa52 | 44 | * @defgroup BiquadCascadeDF2T Biquad Cascade IIR Filters Using a Direct Form II Transposed Structure |
emilmont | 1:fdd22bb7aa52 | 45 | * |
emilmont | 1:fdd22bb7aa52 | 46 | * This set of functions implements arbitrary order recursive (IIR) filters using a transposed direct form II structure. |
emilmont | 1:fdd22bb7aa52 | 47 | * The filters are implemented as a cascade of second order Biquad sections. |
emilmont | 1:fdd22bb7aa52 | 48 | * These functions provide a slight memory savings as compared to the direct form I Biquad filter functions. |
emilmont | 1:fdd22bb7aa52 | 49 | * Only floating-point data is supported. |
emilmont | 1:fdd22bb7aa52 | 50 | * |
emilmont | 1:fdd22bb7aa52 | 51 | * This function operate on blocks of input and output data and each call to the function |
emilmont | 1:fdd22bb7aa52 | 52 | * processes <code>blockSize</code> samples through the filter. |
emilmont | 1:fdd22bb7aa52 | 53 | * <code>pSrc</code> points to the array of input data and |
emilmont | 1:fdd22bb7aa52 | 54 | * <code>pDst</code> points to the array of output data. |
emilmont | 1:fdd22bb7aa52 | 55 | * Both arrays contain <code>blockSize</code> values. |
emilmont | 1:fdd22bb7aa52 | 56 | * |
emilmont | 1:fdd22bb7aa52 | 57 | * \par Algorithm |
emilmont | 1:fdd22bb7aa52 | 58 | * Each Biquad stage implements a second order filter using the difference equation: |
emilmont | 1:fdd22bb7aa52 | 59 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 60 | * y[n] = b0 * x[n] + d1 |
emilmont | 1:fdd22bb7aa52 | 61 | * d1 = b1 * x[n] + a1 * y[n] + d2 |
emilmont | 1:fdd22bb7aa52 | 62 | * d2 = b2 * x[n] + a2 * y[n] |
emilmont | 1:fdd22bb7aa52 | 63 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 64 | * where d1 and d2 represent the two state values. |
emilmont | 1:fdd22bb7aa52 | 65 | * |
emilmont | 1:fdd22bb7aa52 | 66 | * \par |
emilmont | 1:fdd22bb7aa52 | 67 | * A Biquad filter using a transposed Direct Form II structure is shown below. |
emilmont | 1:fdd22bb7aa52 | 68 | * \image html BiquadDF2Transposed.gif "Single transposed Direct Form II Biquad" |
emilmont | 1:fdd22bb7aa52 | 69 | * Coefficients <code>b0, b1, and b2 </code> multiply the input signal <code>x[n]</code> and are referred to as the feedforward coefficients. |
emilmont | 1:fdd22bb7aa52 | 70 | * Coefficients <code>a1</code> and <code>a2</code> multiply the output signal <code>y[n]</code> and are referred to as the feedback coefficients. |
emilmont | 1:fdd22bb7aa52 | 71 | * Pay careful attention to the sign of the feedback coefficients. |
emilmont | 1:fdd22bb7aa52 | 72 | * Some design tools flip the sign of the feedback coefficients: |
emilmont | 1:fdd22bb7aa52 | 73 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 74 | * y[n] = b0 * x[n] + d1; |
emilmont | 1:fdd22bb7aa52 | 75 | * d1 = b1 * x[n] - a1 * y[n] + d2; |
emilmont | 1:fdd22bb7aa52 | 76 | * d2 = b2 * x[n] - a2 * y[n]; |
emilmont | 1:fdd22bb7aa52 | 77 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 78 | * In this case the feedback coefficients <code>a1</code> and <code>a2</code> must be negated when used with the CMSIS DSP Library. |
emilmont | 1:fdd22bb7aa52 | 79 | * |
emilmont | 1:fdd22bb7aa52 | 80 | * \par |
emilmont | 1:fdd22bb7aa52 | 81 | * Higher order filters are realized as a cascade of second order sections. |
emilmont | 1:fdd22bb7aa52 | 82 | * <code>numStages</code> refers to the number of second order stages used. |
emilmont | 1:fdd22bb7aa52 | 83 | * For example, an 8th order filter would be realized with <code>numStages=4</code> second order stages. |
emilmont | 1:fdd22bb7aa52 | 84 | * A 9th order filter would be realized with <code>numStages=5</code> second order stages with the |
emilmont | 1:fdd22bb7aa52 | 85 | * coefficients for one of the stages configured as a first order filter (<code>b2=0</code> and <code>a2=0</code>). |
emilmont | 1:fdd22bb7aa52 | 86 | * |
emilmont | 1:fdd22bb7aa52 | 87 | * \par |
emilmont | 1:fdd22bb7aa52 | 88 | * <code>pState</code> points to the state variable array. |
emilmont | 1:fdd22bb7aa52 | 89 | * Each Biquad stage has 2 state variables <code>d1</code> and <code>d2</code>. |
emilmont | 1:fdd22bb7aa52 | 90 | * The state variables are arranged in the <code>pState</code> array as: |
emilmont | 1:fdd22bb7aa52 | 91 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 92 | * {d11, d12, d21, d22, ...} |
emilmont | 1:fdd22bb7aa52 | 93 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 94 | * where <code>d1x</code> refers to the state variables for the first Biquad and |
emilmont | 1:fdd22bb7aa52 | 95 | * <code>d2x</code> refers to the state variables for the second Biquad. |
emilmont | 1:fdd22bb7aa52 | 96 | * The state array has a total length of <code>2*numStages</code> values. |
emilmont | 1:fdd22bb7aa52 | 97 | * The state variables are updated after each block of data is processed; the coefficients are untouched. |
emilmont | 1:fdd22bb7aa52 | 98 | * |
emilmont | 1:fdd22bb7aa52 | 99 | * \par |
emilmont | 1:fdd22bb7aa52 | 100 | * The CMSIS library contains Biquad filters in both Direct Form I and transposed Direct Form II. |
emilmont | 1:fdd22bb7aa52 | 101 | * The advantage of the Direct Form I structure is that it is numerically more robust for fixed-point data types. |
emilmont | 1:fdd22bb7aa52 | 102 | * That is why the Direct Form I structure supports Q15 and Q31 data types. |
emilmont | 1:fdd22bb7aa52 | 103 | * 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>. |
emilmont | 1:fdd22bb7aa52 | 104 | * Because of this, the CMSIS library only has a floating-point version of the Direct Form II Biquad. |
emilmont | 1:fdd22bb7aa52 | 105 | * 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. |
emilmont | 1:fdd22bb7aa52 | 106 | * |
emilmont | 1:fdd22bb7aa52 | 107 | * \par Instance Structure |
emilmont | 1:fdd22bb7aa52 | 108 | * The coefficients and state variables for a filter are stored together in an instance data structure. |
emilmont | 1:fdd22bb7aa52 | 109 | * A separate instance structure must be defined for each filter. |
emilmont | 1:fdd22bb7aa52 | 110 | * Coefficient arrays may be shared among several instances while state variable arrays cannot be shared. |
emilmont | 1:fdd22bb7aa52 | 111 | * |
emilmont | 1:fdd22bb7aa52 | 112 | * \par Init Functions |
emilmont | 1:fdd22bb7aa52 | 113 | * There is also an associated initialization function. |
emilmont | 1:fdd22bb7aa52 | 114 | * The initialization function performs following operations: |
emilmont | 1:fdd22bb7aa52 | 115 | * - Sets the values of the internal structure fields. |
emilmont | 1:fdd22bb7aa52 | 116 | * - Zeros out the values in the state buffer. |
emilmont | 1:fdd22bb7aa52 | 117 | * |
emilmont | 1:fdd22bb7aa52 | 118 | * \par |
emilmont | 1:fdd22bb7aa52 | 119 | * Use of the initialization function is optional. |
emilmont | 1:fdd22bb7aa52 | 120 | * However, if the initialization function is used, then the instance structure cannot be placed into a const data section. |
emilmont | 1:fdd22bb7aa52 | 121 | * To place an instance structure into a const data section, the instance structure must be manually initialized. |
emilmont | 1:fdd22bb7aa52 | 122 | * Set the values in the state buffer to zeros before static initialization. |
emilmont | 1:fdd22bb7aa52 | 123 | * For example, to statically initialize the instance structure use |
emilmont | 1:fdd22bb7aa52 | 124 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 125 | * arm_biquad_cascade_df2T_instance_f32 S1 = {numStages, pState, pCoeffs}; |
emilmont | 1:fdd22bb7aa52 | 126 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 127 | * where <code>numStages</code> is the number of Biquad stages in the filter; <code>pState</code> is the address of the state buffer. |
emilmont | 1:fdd22bb7aa52 | 128 | * <code>pCoeffs</code> is the address of the coefficient buffer; |
emilmont | 1:fdd22bb7aa52 | 129 | * |
emilmont | 1:fdd22bb7aa52 | 130 | */ |
emilmont | 1:fdd22bb7aa52 | 131 | |
emilmont | 1:fdd22bb7aa52 | 132 | /** |
emilmont | 1:fdd22bb7aa52 | 133 | * @addtogroup BiquadCascadeDF2T |
emilmont | 1:fdd22bb7aa52 | 134 | * @{ |
emilmont | 1:fdd22bb7aa52 | 135 | */ |
emilmont | 1:fdd22bb7aa52 | 136 | |
emilmont | 1:fdd22bb7aa52 | 137 | /** |
emilmont | 1:fdd22bb7aa52 | 138 | * @brief Processing function for the floating-point transposed direct form II Biquad cascade filter. |
emilmont | 1:fdd22bb7aa52 | 139 | * @param[in] *S points to an instance of the filter data structure. |
emilmont | 1:fdd22bb7aa52 | 140 | * @param[in] *pSrc points to the block of input data. |
emilmont | 1:fdd22bb7aa52 | 141 | * @param[out] *pDst points to the block of output data |
emilmont | 1:fdd22bb7aa52 | 142 | * @param[in] blockSize number of samples to process. |
emilmont | 1:fdd22bb7aa52 | 143 | * @return none. |
emilmont | 1:fdd22bb7aa52 | 144 | */ |
emilmont | 1:fdd22bb7aa52 | 145 | |
emilmont | 1:fdd22bb7aa52 | 146 | void arm_biquad_cascade_df2T_f32( |
emilmont | 1:fdd22bb7aa52 | 147 | const arm_biquad_cascade_df2T_instance_f32 * S, |
emilmont | 1:fdd22bb7aa52 | 148 | float32_t * pSrc, |
emilmont | 1:fdd22bb7aa52 | 149 | float32_t * pDst, |
emilmont | 1:fdd22bb7aa52 | 150 | uint32_t blockSize) |
emilmont | 1:fdd22bb7aa52 | 151 | { |
emilmont | 1:fdd22bb7aa52 | 152 | |
emilmont | 1:fdd22bb7aa52 | 153 | float32_t *pIn = pSrc; /* source pointer */ |
emilmont | 1:fdd22bb7aa52 | 154 | float32_t *pOut = pDst; /* destination pointer */ |
emilmont | 1:fdd22bb7aa52 | 155 | float32_t *pState = S->pState; /* State pointer */ |
emilmont | 1:fdd22bb7aa52 | 156 | float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */ |
emilmont | 1:fdd22bb7aa52 | 157 | float32_t acc0; /* accumulator */ |
emilmont | 1:fdd22bb7aa52 | 158 | float32_t b0, b1, b2, a1, a2; /* Filter coefficients */ |
emilmont | 1:fdd22bb7aa52 | 159 | float32_t Xn; /* temporary input */ |
emilmont | 1:fdd22bb7aa52 | 160 | float32_t d1, d2; /* state variables */ |
emilmont | 1:fdd22bb7aa52 | 161 | uint32_t sample, stage = S->numStages; /* loop counters */ |
emilmont | 1:fdd22bb7aa52 | 162 | |
emilmont | 1:fdd22bb7aa52 | 163 | #ifndef ARM_MATH_CM0 |
emilmont | 1:fdd22bb7aa52 | 164 | |
emilmont | 1:fdd22bb7aa52 | 165 | float32_t Xn1, Xn2; /* Input State variables */ |
emilmont | 1:fdd22bb7aa52 | 166 | float32_t acc1; /* accumulator */ |
emilmont | 1:fdd22bb7aa52 | 167 | |
emilmont | 1:fdd22bb7aa52 | 168 | |
emilmont | 1:fdd22bb7aa52 | 169 | |
emilmont | 1:fdd22bb7aa52 | 170 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
emilmont | 1:fdd22bb7aa52 | 171 | do |
emilmont | 1:fdd22bb7aa52 | 172 | { |
emilmont | 1:fdd22bb7aa52 | 173 | /* Reading the coefficients */ |
emilmont | 1:fdd22bb7aa52 | 174 | b0 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 175 | b1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 176 | b2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 177 | a1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 178 | a2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 179 | |
emilmont | 1:fdd22bb7aa52 | 180 | /*Reading the state values */ |
emilmont | 1:fdd22bb7aa52 | 181 | d1 = pState[0]; |
emilmont | 1:fdd22bb7aa52 | 182 | d2 = pState[1]; |
emilmont | 1:fdd22bb7aa52 | 183 | |
emilmont | 1:fdd22bb7aa52 | 184 | /* Apply loop unrolling and compute 4 output values simultaneously. */ |
emilmont | 1:fdd22bb7aa52 | 185 | sample = blockSize >> 2u; |
emilmont | 1:fdd22bb7aa52 | 186 | |
emilmont | 1:fdd22bb7aa52 | 187 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
emilmont | 1:fdd22bb7aa52 | 188 | ** a second loop below computes the remaining 1 to 3 samples. */ |
emilmont | 1:fdd22bb7aa52 | 189 | while(sample > 0u) |
emilmont | 1:fdd22bb7aa52 | 190 | { |
emilmont | 1:fdd22bb7aa52 | 191 | |
emilmont | 1:fdd22bb7aa52 | 192 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 193 | /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
emilmont | 1:fdd22bb7aa52 | 194 | /* d2 = b2 * x[n] + a2 * y[n] */ |
emilmont | 1:fdd22bb7aa52 | 195 | |
emilmont | 1:fdd22bb7aa52 | 196 | /* Read the first input */ |
emilmont | 1:fdd22bb7aa52 | 197 | Xn1 = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 198 | |
emilmont | 1:fdd22bb7aa52 | 199 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 200 | acc0 = (b0 * Xn1) + d1; |
emilmont | 1:fdd22bb7aa52 | 201 | |
emilmont | 1:fdd22bb7aa52 | 202 | /* d1 = b1 * x[n] + d2 */ |
emilmont | 1:fdd22bb7aa52 | 203 | d1 = (b1 * Xn1) + d2; |
emilmont | 1:fdd22bb7aa52 | 204 | |
emilmont | 1:fdd22bb7aa52 | 205 | /* d2 = b2 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 206 | d2 = (b2 * Xn1); |
emilmont | 1:fdd22bb7aa52 | 207 | |
emilmont | 1:fdd22bb7aa52 | 208 | /* Read the second input */ |
emilmont | 1:fdd22bb7aa52 | 209 | Xn2 = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 210 | |
emilmont | 1:fdd22bb7aa52 | 211 | /* d1 = b1 * x[n] + a1 * y[n] */ |
emilmont | 1:fdd22bb7aa52 | 212 | d1 = (a1 * acc0) + d1; |
emilmont | 1:fdd22bb7aa52 | 213 | |
emilmont | 1:fdd22bb7aa52 | 214 | /* Store the result in the accumulator in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 215 | *pOut++ = acc0; |
emilmont | 1:fdd22bb7aa52 | 216 | |
emilmont | 1:fdd22bb7aa52 | 217 | d2 = (a2 * acc0) + d2; |
emilmont | 1:fdd22bb7aa52 | 218 | |
emilmont | 1:fdd22bb7aa52 | 219 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 220 | acc1 = (b0 * Xn2) + d1; |
emilmont | 1:fdd22bb7aa52 | 221 | |
emilmont | 1:fdd22bb7aa52 | 222 | /* Read the third input */ |
emilmont | 1:fdd22bb7aa52 | 223 | Xn1 = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 224 | |
emilmont | 1:fdd22bb7aa52 | 225 | d1 = (b1 * Xn2) + d2; |
emilmont | 1:fdd22bb7aa52 | 226 | |
emilmont | 1:fdd22bb7aa52 | 227 | d2 = (b2 * Xn2); |
emilmont | 1:fdd22bb7aa52 | 228 | |
emilmont | 1:fdd22bb7aa52 | 229 | /* Store the result in the accumulator in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 230 | *pOut++ = acc1; |
emilmont | 1:fdd22bb7aa52 | 231 | |
emilmont | 1:fdd22bb7aa52 | 232 | d1 = (a1 * acc1) + d1; |
emilmont | 1:fdd22bb7aa52 | 233 | |
emilmont | 1:fdd22bb7aa52 | 234 | d2 = (a2 * acc1) + d2; |
emilmont | 1:fdd22bb7aa52 | 235 | |
emilmont | 1:fdd22bb7aa52 | 236 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 237 | acc0 = (b0 * Xn1) + d1; |
emilmont | 1:fdd22bb7aa52 | 238 | |
emilmont | 1:fdd22bb7aa52 | 239 | d1 = (b1 * Xn1) + d2; |
emilmont | 1:fdd22bb7aa52 | 240 | |
emilmont | 1:fdd22bb7aa52 | 241 | d2 = (b2 * Xn1); |
emilmont | 1:fdd22bb7aa52 | 242 | |
emilmont | 1:fdd22bb7aa52 | 243 | /* Read the fourth input */ |
emilmont | 1:fdd22bb7aa52 | 244 | Xn2 = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 245 | |
emilmont | 1:fdd22bb7aa52 | 246 | d1 = (a1 * acc0) + d1; |
emilmont | 1:fdd22bb7aa52 | 247 | |
emilmont | 1:fdd22bb7aa52 | 248 | /* Store the result in the accumulator in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 249 | *pOut++ = acc0; |
emilmont | 1:fdd22bb7aa52 | 250 | |
emilmont | 1:fdd22bb7aa52 | 251 | d2 = (a2 * acc0) + d2; |
emilmont | 1:fdd22bb7aa52 | 252 | |
emilmont | 1:fdd22bb7aa52 | 253 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 254 | acc1 = (b0 * Xn2) + d1; |
emilmont | 1:fdd22bb7aa52 | 255 | |
emilmont | 1:fdd22bb7aa52 | 256 | d1 = (b1 * Xn2) + d2; |
emilmont | 1:fdd22bb7aa52 | 257 | |
emilmont | 1:fdd22bb7aa52 | 258 | d2 = (b2 * Xn2); |
emilmont | 1:fdd22bb7aa52 | 259 | |
emilmont | 1:fdd22bb7aa52 | 260 | /* Store the result in the accumulator in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 261 | *pOut++ = acc1; |
emilmont | 1:fdd22bb7aa52 | 262 | |
emilmont | 1:fdd22bb7aa52 | 263 | d1 = (a1 * acc1) + d1; |
emilmont | 1:fdd22bb7aa52 | 264 | |
emilmont | 1:fdd22bb7aa52 | 265 | d2 = (a2 * acc1) + d2; |
emilmont | 1:fdd22bb7aa52 | 266 | |
emilmont | 1:fdd22bb7aa52 | 267 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 268 | sample--; |
emilmont | 1:fdd22bb7aa52 | 269 | |
emilmont | 1:fdd22bb7aa52 | 270 | } |
emilmont | 1:fdd22bb7aa52 | 271 | |
emilmont | 1:fdd22bb7aa52 | 272 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
emilmont | 1:fdd22bb7aa52 | 273 | ** No loop unrolling is used. */ |
emilmont | 1:fdd22bb7aa52 | 274 | sample = blockSize & 0x3u; |
emilmont | 1:fdd22bb7aa52 | 275 | |
emilmont | 1:fdd22bb7aa52 | 276 | while(sample > 0u) |
emilmont | 1:fdd22bb7aa52 | 277 | { |
emilmont | 1:fdd22bb7aa52 | 278 | /* Read the input */ |
emilmont | 1:fdd22bb7aa52 | 279 | Xn = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 280 | |
emilmont | 1:fdd22bb7aa52 | 281 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 282 | acc0 = (b0 * Xn) + d1; |
emilmont | 1:fdd22bb7aa52 | 283 | |
emilmont | 1:fdd22bb7aa52 | 284 | /* Store the result in the accumulator in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 285 | *pOut++ = acc0; |
emilmont | 1:fdd22bb7aa52 | 286 | |
emilmont | 1:fdd22bb7aa52 | 287 | /* Every time after the output is computed state should be updated. */ |
emilmont | 1:fdd22bb7aa52 | 288 | /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
emilmont | 1:fdd22bb7aa52 | 289 | d1 = ((b1 * Xn) + (a1 * acc0)) + d2; |
emilmont | 1:fdd22bb7aa52 | 290 | |
emilmont | 1:fdd22bb7aa52 | 291 | /* d2 = b2 * x[n] + a2 * y[n] */ |
emilmont | 1:fdd22bb7aa52 | 292 | d2 = (b2 * Xn) + (a2 * acc0); |
emilmont | 1:fdd22bb7aa52 | 293 | |
emilmont | 1:fdd22bb7aa52 | 294 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 295 | sample--; |
emilmont | 1:fdd22bb7aa52 | 296 | } |
emilmont | 1:fdd22bb7aa52 | 297 | |
emilmont | 1:fdd22bb7aa52 | 298 | /* Store the updated state variables back into the state array */ |
emilmont | 1:fdd22bb7aa52 | 299 | *pState++ = d1; |
emilmont | 1:fdd22bb7aa52 | 300 | *pState++ = d2; |
emilmont | 1:fdd22bb7aa52 | 301 | |
emilmont | 1:fdd22bb7aa52 | 302 | /* The current stage input is given as the output to the next stage */ |
emilmont | 1:fdd22bb7aa52 | 303 | pIn = pDst; |
emilmont | 1:fdd22bb7aa52 | 304 | |
emilmont | 1:fdd22bb7aa52 | 305 | /*Reset the output working pointer */ |
emilmont | 1:fdd22bb7aa52 | 306 | pOut = pDst; |
emilmont | 1:fdd22bb7aa52 | 307 | |
emilmont | 1:fdd22bb7aa52 | 308 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 309 | stage--; |
emilmont | 1:fdd22bb7aa52 | 310 | |
emilmont | 1:fdd22bb7aa52 | 311 | } while(stage > 0u); |
emilmont | 1:fdd22bb7aa52 | 312 | |
emilmont | 1:fdd22bb7aa52 | 313 | #else |
emilmont | 1:fdd22bb7aa52 | 314 | |
emilmont | 1:fdd22bb7aa52 | 315 | /* Run the below code for Cortex-M0 */ |
emilmont | 1:fdd22bb7aa52 | 316 | |
emilmont | 1:fdd22bb7aa52 | 317 | do |
emilmont | 1:fdd22bb7aa52 | 318 | { |
emilmont | 1:fdd22bb7aa52 | 319 | /* Reading the coefficients */ |
emilmont | 1:fdd22bb7aa52 | 320 | b0 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 321 | b1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 322 | b2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 323 | a1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 324 | a2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 325 | |
emilmont | 1:fdd22bb7aa52 | 326 | /*Reading the state values */ |
emilmont | 1:fdd22bb7aa52 | 327 | d1 = pState[0]; |
emilmont | 1:fdd22bb7aa52 | 328 | d2 = pState[1]; |
emilmont | 1:fdd22bb7aa52 | 329 | |
emilmont | 1:fdd22bb7aa52 | 330 | |
emilmont | 1:fdd22bb7aa52 | 331 | sample = blockSize; |
emilmont | 1:fdd22bb7aa52 | 332 | |
emilmont | 1:fdd22bb7aa52 | 333 | while(sample > 0u) |
emilmont | 1:fdd22bb7aa52 | 334 | { |
emilmont | 1:fdd22bb7aa52 | 335 | /* Read the input */ |
emilmont | 1:fdd22bb7aa52 | 336 | Xn = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 337 | |
emilmont | 1:fdd22bb7aa52 | 338 | /* y[n] = b0 * x[n] + d1 */ |
emilmont | 1:fdd22bb7aa52 | 339 | acc0 = (b0 * Xn) + d1; |
emilmont | 1:fdd22bb7aa52 | 340 | |
emilmont | 1:fdd22bb7aa52 | 341 | /* Store the result in the accumulator in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 342 | *pOut++ = acc0; |
emilmont | 1:fdd22bb7aa52 | 343 | |
emilmont | 1:fdd22bb7aa52 | 344 | /* Every time after the output is computed state should be updated. */ |
emilmont | 1:fdd22bb7aa52 | 345 | /* d1 = b1 * x[n] + a1 * y[n] + d2 */ |
emilmont | 1:fdd22bb7aa52 | 346 | d1 = ((b1 * Xn) + (a1 * acc0)) + d2; |
emilmont | 1:fdd22bb7aa52 | 347 | |
emilmont | 1:fdd22bb7aa52 | 348 | /* d2 = b2 * x[n] + a2 * y[n] */ |
emilmont | 1:fdd22bb7aa52 | 349 | d2 = (b2 * Xn) + (a2 * acc0); |
emilmont | 1:fdd22bb7aa52 | 350 | |
emilmont | 1:fdd22bb7aa52 | 351 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 352 | sample--; |
emilmont | 1:fdd22bb7aa52 | 353 | } |
emilmont | 1:fdd22bb7aa52 | 354 | |
emilmont | 1:fdd22bb7aa52 | 355 | /* Store the updated state variables back into the state array */ |
emilmont | 1:fdd22bb7aa52 | 356 | *pState++ = d1; |
emilmont | 1:fdd22bb7aa52 | 357 | *pState++ = d2; |
emilmont | 1:fdd22bb7aa52 | 358 | |
emilmont | 1:fdd22bb7aa52 | 359 | /* The current stage input is given as the output to the next stage */ |
emilmont | 1:fdd22bb7aa52 | 360 | pIn = pDst; |
emilmont | 1:fdd22bb7aa52 | 361 | |
emilmont | 1:fdd22bb7aa52 | 362 | /*Reset the output working pointer */ |
emilmont | 1:fdd22bb7aa52 | 363 | pOut = pDst; |
emilmont | 1:fdd22bb7aa52 | 364 | |
emilmont | 1:fdd22bb7aa52 | 365 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 366 | stage--; |
emilmont | 1:fdd22bb7aa52 | 367 | |
emilmont | 1:fdd22bb7aa52 | 368 | } while(stage > 0u); |
emilmont | 1:fdd22bb7aa52 | 369 | |
emilmont | 1:fdd22bb7aa52 | 370 | #endif /* #ifndef ARM_MATH_CM0 */ |
emilmont | 1:fdd22bb7aa52 | 371 | |
emilmont | 1:fdd22bb7aa52 | 372 | } |
emilmont | 1:fdd22bb7aa52 | 373 | |
emilmont | 1:fdd22bb7aa52 | 374 | |
emilmont | 1:fdd22bb7aa52 | 375 | /** |
emilmont | 1:fdd22bb7aa52 | 376 | * @} end of BiquadCascadeDF2T group |
emilmont | 1:fdd22bb7aa52 | 377 | */ |