CMSIS DSP library
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cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df1_32x64_q31.c@3:7a284390b0ce, 2013-11-08 (annotated)
- Committer:
- mbed_official
- Date:
- Fri Nov 08 13:45:10 2013 +0000
- Revision:
- 3:7a284390b0ce
- Parent:
- 2:da51fb522205
Synchronized with git revision e69956aba2f68a2a26ac26b051f8d349deaa1ce8
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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emilmont | 1:fdd22bb7aa52 | 1 | /* ---------------------------------------------------------------------- |
mbed_official | 3:7a284390b0ce | 2 | * Copyright (C) 2010-2013 ARM Limited. All rights reserved. |
emilmont | 1:fdd22bb7aa52 | 3 | * |
mbed_official | 3:7a284390b0ce | 4 | * $Date: 17. January 2013 |
mbed_official | 3:7a284390b0ce | 5 | * $Revision: V1.4.1 |
emilmont | 1:fdd22bb7aa52 | 6 | * |
emilmont | 2:da51fb522205 | 7 | * Project: CMSIS DSP Library |
emilmont | 2:da51fb522205 | 8 | * Title: arm_biquad_cascade_df1_32x64_q31.c |
emilmont | 1:fdd22bb7aa52 | 9 | * |
emilmont | 2:da51fb522205 | 10 | * Description: High precision Q31 Biquad cascade filter processing function |
emilmont | 1:fdd22bb7aa52 | 11 | * |
emilmont | 1:fdd22bb7aa52 | 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
emilmont | 1:fdd22bb7aa52 | 13 | * |
mbed_official | 3:7a284390b0ce | 14 | * Redistribution and use in source and binary forms, with or without |
mbed_official | 3:7a284390b0ce | 15 | * modification, are permitted provided that the following conditions |
mbed_official | 3:7a284390b0ce | 16 | * are met: |
mbed_official | 3:7a284390b0ce | 17 | * - Redistributions of source code must retain the above copyright |
mbed_official | 3:7a284390b0ce | 18 | * notice, this list of conditions and the following disclaimer. |
mbed_official | 3:7a284390b0ce | 19 | * - Redistributions in binary form must reproduce the above copyright |
mbed_official | 3:7a284390b0ce | 20 | * notice, this list of conditions and the following disclaimer in |
mbed_official | 3:7a284390b0ce | 21 | * the documentation and/or other materials provided with the |
mbed_official | 3:7a284390b0ce | 22 | * distribution. |
mbed_official | 3:7a284390b0ce | 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
mbed_official | 3:7a284390b0ce | 24 | * may be used to endorse or promote products derived from this |
mbed_official | 3:7a284390b0ce | 25 | * software without specific prior written permission. |
mbed_official | 3:7a284390b0ce | 26 | * |
mbed_official | 3:7a284390b0ce | 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
mbed_official | 3:7a284390b0ce | 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
mbed_official | 3:7a284390b0ce | 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
mbed_official | 3:7a284390b0ce | 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
mbed_official | 3:7a284390b0ce | 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
mbed_official | 3:7a284390b0ce | 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
mbed_official | 3:7a284390b0ce | 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
mbed_official | 3:7a284390b0ce | 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
mbed_official | 3:7a284390b0ce | 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
mbed_official | 3:7a284390b0ce | 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
mbed_official | 3:7a284390b0ce | 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
mbed_official | 3:7a284390b0ce | 38 | * POSSIBILITY OF SUCH DAMAGE. |
emilmont | 1:fdd22bb7aa52 | 39 | * -------------------------------------------------------------------- */ |
emilmont | 1:fdd22bb7aa52 | 40 | |
emilmont | 1:fdd22bb7aa52 | 41 | #include "arm_math.h" |
emilmont | 1:fdd22bb7aa52 | 42 | |
emilmont | 1:fdd22bb7aa52 | 43 | /** |
emilmont | 1:fdd22bb7aa52 | 44 | * @ingroup groupFilters |
emilmont | 1:fdd22bb7aa52 | 45 | */ |
emilmont | 1:fdd22bb7aa52 | 46 | |
emilmont | 1:fdd22bb7aa52 | 47 | /** |
emilmont | 1:fdd22bb7aa52 | 48 | * @defgroup BiquadCascadeDF1_32x64 High Precision Q31 Biquad Cascade Filter |
emilmont | 1:fdd22bb7aa52 | 49 | * |
emilmont | 1:fdd22bb7aa52 | 50 | * This function implements a high precision Biquad cascade filter which operates on |
emilmont | 1:fdd22bb7aa52 | 51 | * Q31 data values. The filter coefficients are in 1.31 format and the state variables |
emilmont | 1:fdd22bb7aa52 | 52 | * are in 1.63 format. The double precision state variables reduce quantization noise |
emilmont | 1:fdd22bb7aa52 | 53 | * in the filter and provide a cleaner output. |
emilmont | 1:fdd22bb7aa52 | 54 | * These filters are particularly useful when implementing filters in which the |
emilmont | 1:fdd22bb7aa52 | 55 | * singularities are close to the unit circle. This is common for low pass or high |
emilmont | 1:fdd22bb7aa52 | 56 | * pass filters with very low cutoff frequencies. |
emilmont | 1:fdd22bb7aa52 | 57 | * |
emilmont | 1:fdd22bb7aa52 | 58 | * The function operates on blocks of input and output data |
emilmont | 1:fdd22bb7aa52 | 59 | * and each call to the function processes <code>blockSize</code> samples through |
emilmont | 1:fdd22bb7aa52 | 60 | * the filter. <code>pSrc</code> and <code>pDst</code> points to input and output arrays |
emilmont | 1:fdd22bb7aa52 | 61 | * containing <code>blockSize</code> Q31 values. |
emilmont | 1:fdd22bb7aa52 | 62 | * |
emilmont | 1:fdd22bb7aa52 | 63 | * \par Algorithm |
emilmont | 1:fdd22bb7aa52 | 64 | * Each Biquad stage implements a second order filter using the difference equation: |
emilmont | 1:fdd22bb7aa52 | 65 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 66 | * y[n] = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] |
emilmont | 1:fdd22bb7aa52 | 67 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 68 | * A Direct Form I algorithm is used with 5 coefficients and 4 state variables per stage. |
emilmont | 1:fdd22bb7aa52 | 69 | * \image html Biquad.gif "Single Biquad filter stage" |
emilmont | 1:fdd22bb7aa52 | 70 | * 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 | 71 | * 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 | 72 | * Pay careful attention to the sign of the feedback coefficients. |
emilmont | 1:fdd22bb7aa52 | 73 | * Some design tools use the difference equation |
emilmont | 1:fdd22bb7aa52 | 74 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 75 | * y[n] = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] - a1 * y[n-1] - a2 * y[n-2] |
emilmont | 1:fdd22bb7aa52 | 76 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 77 | * 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 | 78 | * |
emilmont | 1:fdd22bb7aa52 | 79 | * \par |
emilmont | 1:fdd22bb7aa52 | 80 | * Higher order filters are realized as a cascade of second order sections. |
emilmont | 1:fdd22bb7aa52 | 81 | * <code>numStages</code> refers to the number of second order stages used. |
emilmont | 1:fdd22bb7aa52 | 82 | * For example, an 8th order filter would be realized with <code>numStages=4</code> second order stages. |
emilmont | 1:fdd22bb7aa52 | 83 | * \image html BiquadCascade.gif "8th order filter using a cascade of Biquad stages" |
emilmont | 1:fdd22bb7aa52 | 84 | * 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>). |
emilmont | 1:fdd22bb7aa52 | 85 | * |
emilmont | 1:fdd22bb7aa52 | 86 | * \par |
emilmont | 1:fdd22bb7aa52 | 87 | * The <code>pState</code> points to state variables array . |
emilmont | 1:fdd22bb7aa52 | 88 | * Each Biquad stage has 4 state variables <code>x[n-1], x[n-2], y[n-1],</code> and <code>y[n-2]</code> and each state variable in 1.63 format to improve precision. |
emilmont | 1:fdd22bb7aa52 | 89 | * The state variables are arranged in the array as: |
emilmont | 1:fdd22bb7aa52 | 90 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 91 | * {x[n-1], x[n-2], y[n-1], y[n-2]} |
emilmont | 1:fdd22bb7aa52 | 92 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 93 | * |
emilmont | 1:fdd22bb7aa52 | 94 | * \par |
emilmont | 1:fdd22bb7aa52 | 95 | * The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on. |
emilmont | 1:fdd22bb7aa52 | 96 | * The state array has a total length of <code>4*numStages</code> values of data in 1.63 format. |
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 Instance Structure |
emilmont | 1:fdd22bb7aa52 | 100 | * The coefficients and state variables for a filter are stored together in an instance data structure. |
emilmont | 1:fdd22bb7aa52 | 101 | * A separate instance structure must be defined for each filter. |
emilmont | 1:fdd22bb7aa52 | 102 | * Coefficient arrays may be shared among several instances while state variable arrays cannot be shared. |
emilmont | 1:fdd22bb7aa52 | 103 | * |
emilmont | 1:fdd22bb7aa52 | 104 | * \par Init Function |
emilmont | 1:fdd22bb7aa52 | 105 | * There is also an associated initialization function which performs the following operations: |
emilmont | 1:fdd22bb7aa52 | 106 | * - Sets the values of the internal structure fields. |
emilmont | 1:fdd22bb7aa52 | 107 | * - Zeros out the values in the state buffer. |
mbed_official | 3:7a284390b0ce | 108 | * To do this manually without calling the init function, assign the follow subfields of the instance structure: |
mbed_official | 3:7a284390b0ce | 109 | * numStages, pCoeffs, postShift, pState. Also set all of the values in pState to zero. |
mbed_official | 3:7a284390b0ce | 110 | * |
emilmont | 1:fdd22bb7aa52 | 111 | * \par |
emilmont | 1:fdd22bb7aa52 | 112 | * Use of the initialization function is optional. |
emilmont | 1:fdd22bb7aa52 | 113 | * However, if the initialization function is used, then the instance structure cannot be placed into a const data section. |
emilmont | 1:fdd22bb7aa52 | 114 | * To place an instance structure into a const data section, the instance structure must be manually initialized. |
emilmont | 1:fdd22bb7aa52 | 115 | * Set the values in the state buffer to zeros before static initialization. |
emilmont | 1:fdd22bb7aa52 | 116 | * For example, to statically initialize the filter instance structure use |
emilmont | 1:fdd22bb7aa52 | 117 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 118 | * arm_biquad_cas_df1_32x64_ins_q31 S1 = {numStages, pState, pCoeffs, postShift}; |
emilmont | 1:fdd22bb7aa52 | 119 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 120 | * 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 | 121 | * <code>pCoeffs</code> is the address of the coefficient buffer; <code>postShift</code> shift to be applied which is described in detail below. |
emilmont | 1:fdd22bb7aa52 | 122 | * \par Fixed-Point Behavior |
emilmont | 1:fdd22bb7aa52 | 123 | * Care must be taken while using Biquad Cascade 32x64 filter function. |
emilmont | 1:fdd22bb7aa52 | 124 | * Following issues must be considered: |
emilmont | 1:fdd22bb7aa52 | 125 | * - Scaling of coefficients |
emilmont | 1:fdd22bb7aa52 | 126 | * - Filter gain |
emilmont | 1:fdd22bb7aa52 | 127 | * - Overflow and saturation |
emilmont | 1:fdd22bb7aa52 | 128 | * |
emilmont | 1:fdd22bb7aa52 | 129 | * \par |
emilmont | 1:fdd22bb7aa52 | 130 | * Filter coefficients are represented as fractional values and |
emilmont | 1:fdd22bb7aa52 | 131 | * restricted to lie in the range <code>[-1 +1)</code>. |
emilmont | 1:fdd22bb7aa52 | 132 | * The processing function has an additional scaling parameter <code>postShift</code> |
emilmont | 1:fdd22bb7aa52 | 133 | * which allows the filter coefficients to exceed the range <code>[+1 -1)</code>. |
emilmont | 1:fdd22bb7aa52 | 134 | * At the output of the filter's accumulator is a shift register which shifts the result by <code>postShift</code> bits. |
emilmont | 1:fdd22bb7aa52 | 135 | * \image html BiquadPostshift.gif "Fixed-point Biquad with shift by postShift bits after accumulator" |
emilmont | 1:fdd22bb7aa52 | 136 | * This essentially scales the filter coefficients by <code>2^postShift</code>. |
emilmont | 1:fdd22bb7aa52 | 137 | * For example, to realize the coefficients |
emilmont | 1:fdd22bb7aa52 | 138 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 139 | * {1.5, -0.8, 1.2, 1.6, -0.9} |
emilmont | 1:fdd22bb7aa52 | 140 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 141 | * set the Coefficient array to: |
emilmont | 1:fdd22bb7aa52 | 142 | * <pre> |
emilmont | 1:fdd22bb7aa52 | 143 | * {0.75, -0.4, 0.6, 0.8, -0.45} |
emilmont | 1:fdd22bb7aa52 | 144 | * </pre> |
emilmont | 1:fdd22bb7aa52 | 145 | * and set <code>postShift=1</code> |
emilmont | 1:fdd22bb7aa52 | 146 | * |
emilmont | 1:fdd22bb7aa52 | 147 | * \par |
emilmont | 1:fdd22bb7aa52 | 148 | * The second thing to keep in mind is the gain through the filter. |
emilmont | 1:fdd22bb7aa52 | 149 | * The frequency response of a Biquad filter is a function of its coefficients. |
emilmont | 1:fdd22bb7aa52 | 150 | * It is possible for the gain through the filter to exceed 1.0 meaning that the filter increases the amplitude of certain frequencies. |
emilmont | 1:fdd22bb7aa52 | 151 | * This means that an input signal with amplitude < 1.0 may result in an output > 1.0 and these are saturated or overflowed based on the implementation of the filter. |
emilmont | 1:fdd22bb7aa52 | 152 | * To avoid this behavior the filter needs to be scaled down such that its peak gain < 1.0 or the input signal must be scaled down so that the combination of input and filter are never overflowed. |
emilmont | 1:fdd22bb7aa52 | 153 | * |
emilmont | 1:fdd22bb7aa52 | 154 | * \par |
emilmont | 1:fdd22bb7aa52 | 155 | * The third item to consider is the overflow and saturation behavior of the fixed-point Q31 version. |
emilmont | 1:fdd22bb7aa52 | 156 | * This is described in the function specific documentation below. |
emilmont | 1:fdd22bb7aa52 | 157 | */ |
emilmont | 1:fdd22bb7aa52 | 158 | |
emilmont | 1:fdd22bb7aa52 | 159 | /** |
emilmont | 1:fdd22bb7aa52 | 160 | * @addtogroup BiquadCascadeDF1_32x64 |
emilmont | 1:fdd22bb7aa52 | 161 | * @{ |
emilmont | 1:fdd22bb7aa52 | 162 | */ |
emilmont | 1:fdd22bb7aa52 | 163 | |
emilmont | 1:fdd22bb7aa52 | 164 | /** |
emilmont | 1:fdd22bb7aa52 | 165 | * @details |
emilmont | 1:fdd22bb7aa52 | 166 | |
emilmont | 1:fdd22bb7aa52 | 167 | * @param[in] *S points to an instance of the high precision Q31 Biquad cascade filter. |
emilmont | 1:fdd22bb7aa52 | 168 | * @param[in] *pSrc points to the block of input data. |
emilmont | 1:fdd22bb7aa52 | 169 | * @param[out] *pDst points to the block of output data. |
emilmont | 1:fdd22bb7aa52 | 170 | * @param[in] blockSize number of samples to process. |
emilmont | 1:fdd22bb7aa52 | 171 | * @return none. |
emilmont | 1:fdd22bb7aa52 | 172 | * |
emilmont | 1:fdd22bb7aa52 | 173 | * \par |
emilmont | 1:fdd22bb7aa52 | 174 | * The function is implemented using an internal 64-bit accumulator. |
emilmont | 1:fdd22bb7aa52 | 175 | * The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit. |
emilmont | 1:fdd22bb7aa52 | 176 | * Thus, if the accumulator result overflows it wraps around rather than clip. |
emilmont | 1:fdd22bb7aa52 | 177 | * In order to avoid overflows completely the input signal must be scaled down by 2 bits and lie in the range [-0.25 +0.25). |
emilmont | 1:fdd22bb7aa52 | 178 | * After all 5 multiply-accumulates are performed, the 2.62 accumulator is shifted by <code>postShift</code> bits and the result truncated to |
emilmont | 1:fdd22bb7aa52 | 179 | * 1.31 format by discarding the low 32 bits. |
emilmont | 1:fdd22bb7aa52 | 180 | * |
emilmont | 1:fdd22bb7aa52 | 181 | * \par |
emilmont | 1:fdd22bb7aa52 | 182 | * Two related functions are provided in the CMSIS DSP library. |
emilmont | 1:fdd22bb7aa52 | 183 | * <code>arm_biquad_cascade_df1_q31()</code> implements a Biquad cascade with 32-bit coefficients and state variables with a Q63 accumulator. |
emilmont | 1:fdd22bb7aa52 | 184 | * <code>arm_biquad_cascade_df1_fast_q31()</code> implements a Biquad cascade with 32-bit coefficients and state variables with a Q31 accumulator. |
emilmont | 1:fdd22bb7aa52 | 185 | */ |
emilmont | 1:fdd22bb7aa52 | 186 | |
emilmont | 1:fdd22bb7aa52 | 187 | void arm_biquad_cas_df1_32x64_q31( |
emilmont | 1:fdd22bb7aa52 | 188 | const arm_biquad_cas_df1_32x64_ins_q31 * S, |
emilmont | 1:fdd22bb7aa52 | 189 | q31_t * pSrc, |
emilmont | 1:fdd22bb7aa52 | 190 | q31_t * pDst, |
emilmont | 1:fdd22bb7aa52 | 191 | uint32_t blockSize) |
emilmont | 1:fdd22bb7aa52 | 192 | { |
emilmont | 1:fdd22bb7aa52 | 193 | q31_t *pIn = pSrc; /* input pointer initialization */ |
emilmont | 1:fdd22bb7aa52 | 194 | q31_t *pOut = pDst; /* output pointer initialization */ |
emilmont | 1:fdd22bb7aa52 | 195 | q63_t *pState = S->pState; /* state pointer initialization */ |
emilmont | 1:fdd22bb7aa52 | 196 | q31_t *pCoeffs = S->pCoeffs; /* coeff pointer initialization */ |
emilmont | 1:fdd22bb7aa52 | 197 | q63_t acc; /* accumulator */ |
emilmont | 1:fdd22bb7aa52 | 198 | q31_t Xn1, Xn2; /* Input Filter state variables */ |
emilmont | 1:fdd22bb7aa52 | 199 | q63_t Yn1, Yn2; /* Output Filter state variables */ |
emilmont | 1:fdd22bb7aa52 | 200 | q31_t b0, b1, b2, a1, a2; /* Filter coefficients */ |
emilmont | 1:fdd22bb7aa52 | 201 | q31_t Xn; /* temporary input */ |
emilmont | 1:fdd22bb7aa52 | 202 | int32_t shift = (int32_t) S->postShift + 1; /* Shift to be applied to the output */ |
emilmont | 1:fdd22bb7aa52 | 203 | uint32_t sample, stage = S->numStages; /* loop counters */ |
emilmont | 1:fdd22bb7aa52 | 204 | q31_t acc_l, acc_h; /* temporary output */ |
emilmont | 1:fdd22bb7aa52 | 205 | uint32_t uShift = ((uint32_t) S->postShift + 1u); |
emilmont | 1:fdd22bb7aa52 | 206 | uint32_t lShift = 32u - uShift; /* Shift to be applied to the output */ |
emilmont | 1:fdd22bb7aa52 | 207 | |
emilmont | 1:fdd22bb7aa52 | 208 | |
mbed_official | 3:7a284390b0ce | 209 | #ifndef ARM_MATH_CM0_FAMILY |
emilmont | 1:fdd22bb7aa52 | 210 | |
emilmont | 1:fdd22bb7aa52 | 211 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
emilmont | 1:fdd22bb7aa52 | 212 | |
emilmont | 1:fdd22bb7aa52 | 213 | do |
emilmont | 1:fdd22bb7aa52 | 214 | { |
emilmont | 1:fdd22bb7aa52 | 215 | /* Reading the coefficients */ |
emilmont | 1:fdd22bb7aa52 | 216 | b0 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 217 | b1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 218 | b2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 219 | a1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 220 | a2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 221 | |
emilmont | 1:fdd22bb7aa52 | 222 | /* Reading the state values */ |
emilmont | 1:fdd22bb7aa52 | 223 | Xn1 = (q31_t) (pState[0]); |
emilmont | 1:fdd22bb7aa52 | 224 | Xn2 = (q31_t) (pState[1]); |
emilmont | 1:fdd22bb7aa52 | 225 | Yn1 = pState[2]; |
emilmont | 1:fdd22bb7aa52 | 226 | Yn2 = pState[3]; |
emilmont | 1:fdd22bb7aa52 | 227 | |
emilmont | 1:fdd22bb7aa52 | 228 | /* Apply loop unrolling and compute 4 output values simultaneously. */ |
emilmont | 1:fdd22bb7aa52 | 229 | /* The variable acc hold output value that is being computed and |
emilmont | 1:fdd22bb7aa52 | 230 | * stored in the destination buffer |
emilmont | 1:fdd22bb7aa52 | 231 | * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] |
emilmont | 1:fdd22bb7aa52 | 232 | */ |
emilmont | 1:fdd22bb7aa52 | 233 | |
emilmont | 1:fdd22bb7aa52 | 234 | sample = blockSize >> 2u; |
emilmont | 1:fdd22bb7aa52 | 235 | |
emilmont | 1:fdd22bb7aa52 | 236 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
emilmont | 1:fdd22bb7aa52 | 237 | ** a second loop below computes the remaining 1 to 3 samples. */ |
emilmont | 1:fdd22bb7aa52 | 238 | while(sample > 0u) |
emilmont | 1:fdd22bb7aa52 | 239 | { |
emilmont | 1:fdd22bb7aa52 | 240 | /* Read the input */ |
emilmont | 1:fdd22bb7aa52 | 241 | Xn = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 242 | |
emilmont | 1:fdd22bb7aa52 | 243 | /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 244 | |
emilmont | 1:fdd22bb7aa52 | 245 | /* acc = b0 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 246 | acc = (q63_t) Xn *b0; |
emilmont | 1:fdd22bb7aa52 | 247 | |
emilmont | 1:fdd22bb7aa52 | 248 | /* acc += b1 * x[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 249 | acc += (q63_t) Xn1 *b1; |
emilmont | 1:fdd22bb7aa52 | 250 | |
emilmont | 1:fdd22bb7aa52 | 251 | /* acc += b[2] * x[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 252 | acc += (q63_t) Xn2 *b2; |
emilmont | 1:fdd22bb7aa52 | 253 | |
emilmont | 1:fdd22bb7aa52 | 254 | /* acc += a1 * y[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 255 | acc += mult32x64(Yn1, a1); |
emilmont | 1:fdd22bb7aa52 | 256 | |
emilmont | 1:fdd22bb7aa52 | 257 | /* acc += a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 258 | acc += mult32x64(Yn2, a2); |
emilmont | 1:fdd22bb7aa52 | 259 | |
emilmont | 1:fdd22bb7aa52 | 260 | /* The result is converted to 1.63 , Yn2 variable is reused */ |
emilmont | 1:fdd22bb7aa52 | 261 | Yn2 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 262 | |
emilmont | 1:fdd22bb7aa52 | 263 | /* Calc lower part of acc */ |
emilmont | 1:fdd22bb7aa52 | 264 | acc_l = acc & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 265 | |
emilmont | 1:fdd22bb7aa52 | 266 | /* Calc upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 267 | acc_h = (acc >> 32) & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 268 | |
emilmont | 1:fdd22bb7aa52 | 269 | /* Apply shift for lower part of acc and upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 270 | acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift; |
emilmont | 1:fdd22bb7aa52 | 271 | |
emilmont | 1:fdd22bb7aa52 | 272 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 273 | *pOut = acc_h; |
emilmont | 1:fdd22bb7aa52 | 274 | |
emilmont | 1:fdd22bb7aa52 | 275 | /* Read the second input into Xn2, to reuse the value */ |
emilmont | 1:fdd22bb7aa52 | 276 | Xn2 = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 277 | |
emilmont | 1:fdd22bb7aa52 | 278 | /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 279 | |
emilmont | 1:fdd22bb7aa52 | 280 | /* acc += b1 * x[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 281 | acc = (q63_t) Xn *b1; |
emilmont | 1:fdd22bb7aa52 | 282 | |
emilmont | 1:fdd22bb7aa52 | 283 | /* acc = b0 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 284 | acc += (q63_t) Xn2 *b0; |
emilmont | 1:fdd22bb7aa52 | 285 | |
emilmont | 1:fdd22bb7aa52 | 286 | /* acc += b[2] * x[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 287 | acc += (q63_t) Xn1 *b2; |
emilmont | 1:fdd22bb7aa52 | 288 | |
emilmont | 1:fdd22bb7aa52 | 289 | /* acc += a1 * y[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 290 | acc += mult32x64(Yn2, a1); |
emilmont | 1:fdd22bb7aa52 | 291 | |
emilmont | 1:fdd22bb7aa52 | 292 | /* acc += a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 293 | acc += mult32x64(Yn1, a2); |
emilmont | 1:fdd22bb7aa52 | 294 | |
emilmont | 1:fdd22bb7aa52 | 295 | /* The result is converted to 1.63, Yn1 variable is reused */ |
emilmont | 1:fdd22bb7aa52 | 296 | Yn1 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 297 | |
emilmont | 1:fdd22bb7aa52 | 298 | /* Calc lower part of acc */ |
emilmont | 1:fdd22bb7aa52 | 299 | acc_l = acc & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 300 | |
emilmont | 1:fdd22bb7aa52 | 301 | /* Calc upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 302 | acc_h = (acc >> 32) & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 303 | |
emilmont | 1:fdd22bb7aa52 | 304 | /* Apply shift for lower part of acc and upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 305 | acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift; |
emilmont | 1:fdd22bb7aa52 | 306 | |
emilmont | 1:fdd22bb7aa52 | 307 | /* Read the third input into Xn1, to reuse the value */ |
emilmont | 1:fdd22bb7aa52 | 308 | Xn1 = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 309 | |
emilmont | 1:fdd22bb7aa52 | 310 | /* The result is converted to 1.31 */ |
emilmont | 1:fdd22bb7aa52 | 311 | /* Store the output in the destination buffer. */ |
emilmont | 1:fdd22bb7aa52 | 312 | *(pOut + 1u) = acc_h; |
emilmont | 1:fdd22bb7aa52 | 313 | |
emilmont | 1:fdd22bb7aa52 | 314 | /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 315 | |
emilmont | 1:fdd22bb7aa52 | 316 | /* acc = b0 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 317 | acc = (q63_t) Xn1 *b0; |
emilmont | 1:fdd22bb7aa52 | 318 | |
emilmont | 1:fdd22bb7aa52 | 319 | /* acc += b1 * x[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 320 | acc += (q63_t) Xn2 *b1; |
emilmont | 1:fdd22bb7aa52 | 321 | |
emilmont | 1:fdd22bb7aa52 | 322 | /* acc += b[2] * x[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 323 | acc += (q63_t) Xn *b2; |
emilmont | 1:fdd22bb7aa52 | 324 | |
emilmont | 1:fdd22bb7aa52 | 325 | /* acc += a1 * y[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 326 | acc += mult32x64(Yn1, a1); |
emilmont | 1:fdd22bb7aa52 | 327 | |
emilmont | 1:fdd22bb7aa52 | 328 | /* acc += a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 329 | acc += mult32x64(Yn2, a2); |
emilmont | 1:fdd22bb7aa52 | 330 | |
emilmont | 1:fdd22bb7aa52 | 331 | /* The result is converted to 1.63, Yn2 variable is reused */ |
emilmont | 1:fdd22bb7aa52 | 332 | Yn2 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 333 | |
emilmont | 1:fdd22bb7aa52 | 334 | /* Calc lower part of acc */ |
emilmont | 1:fdd22bb7aa52 | 335 | acc_l = acc & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 336 | |
emilmont | 1:fdd22bb7aa52 | 337 | /* Calc upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 338 | acc_h = (acc >> 32) & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 339 | |
emilmont | 1:fdd22bb7aa52 | 340 | /* Apply shift for lower part of acc and upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 341 | acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift; |
emilmont | 1:fdd22bb7aa52 | 342 | |
emilmont | 1:fdd22bb7aa52 | 343 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 344 | *(pOut + 2u) = acc_h; |
emilmont | 1:fdd22bb7aa52 | 345 | |
emilmont | 1:fdd22bb7aa52 | 346 | /* Read the fourth input into Xn, to reuse the value */ |
emilmont | 1:fdd22bb7aa52 | 347 | Xn = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 348 | |
emilmont | 1:fdd22bb7aa52 | 349 | /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 350 | /* acc = b0 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 351 | acc = (q63_t) Xn *b0; |
emilmont | 1:fdd22bb7aa52 | 352 | |
emilmont | 1:fdd22bb7aa52 | 353 | /* acc += b1 * x[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 354 | acc += (q63_t) Xn1 *b1; |
emilmont | 1:fdd22bb7aa52 | 355 | |
emilmont | 1:fdd22bb7aa52 | 356 | /* acc += b[2] * x[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 357 | acc += (q63_t) Xn2 *b2; |
emilmont | 1:fdd22bb7aa52 | 358 | |
emilmont | 1:fdd22bb7aa52 | 359 | /* acc += a1 * y[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 360 | acc += mult32x64(Yn2, a1); |
emilmont | 1:fdd22bb7aa52 | 361 | |
emilmont | 1:fdd22bb7aa52 | 362 | /* acc += a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 363 | acc += mult32x64(Yn1, a2); |
emilmont | 1:fdd22bb7aa52 | 364 | |
emilmont | 1:fdd22bb7aa52 | 365 | /* The result is converted to 1.63, Yn1 variable is reused */ |
emilmont | 1:fdd22bb7aa52 | 366 | Yn1 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 367 | |
emilmont | 1:fdd22bb7aa52 | 368 | /* Calc lower part of acc */ |
emilmont | 1:fdd22bb7aa52 | 369 | acc_l = acc & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 370 | |
emilmont | 1:fdd22bb7aa52 | 371 | /* Calc upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 372 | acc_h = (acc >> 32) & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 373 | |
emilmont | 1:fdd22bb7aa52 | 374 | /* Apply shift for lower part of acc and upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 375 | acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift; |
emilmont | 1:fdd22bb7aa52 | 376 | |
emilmont | 1:fdd22bb7aa52 | 377 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 378 | *(pOut + 3u) = acc_h; |
emilmont | 1:fdd22bb7aa52 | 379 | |
emilmont | 1:fdd22bb7aa52 | 380 | /* Every time after the output is computed state should be updated. */ |
emilmont | 1:fdd22bb7aa52 | 381 | /* The states should be updated as: */ |
emilmont | 1:fdd22bb7aa52 | 382 | /* Xn2 = Xn1 */ |
emilmont | 1:fdd22bb7aa52 | 383 | /* Xn1 = Xn */ |
emilmont | 1:fdd22bb7aa52 | 384 | /* Yn2 = Yn1 */ |
emilmont | 1:fdd22bb7aa52 | 385 | /* Yn1 = acc */ |
emilmont | 1:fdd22bb7aa52 | 386 | Xn2 = Xn1; |
emilmont | 1:fdd22bb7aa52 | 387 | Xn1 = Xn; |
emilmont | 1:fdd22bb7aa52 | 388 | |
emilmont | 1:fdd22bb7aa52 | 389 | /* update output pointer */ |
emilmont | 1:fdd22bb7aa52 | 390 | pOut += 4u; |
emilmont | 1:fdd22bb7aa52 | 391 | |
emilmont | 1:fdd22bb7aa52 | 392 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 393 | sample--; |
emilmont | 1:fdd22bb7aa52 | 394 | } |
emilmont | 1:fdd22bb7aa52 | 395 | |
emilmont | 1:fdd22bb7aa52 | 396 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
emilmont | 1:fdd22bb7aa52 | 397 | ** No loop unrolling is used. */ |
emilmont | 1:fdd22bb7aa52 | 398 | sample = (blockSize & 0x3u); |
emilmont | 1:fdd22bb7aa52 | 399 | |
emilmont | 1:fdd22bb7aa52 | 400 | while(sample > 0u) |
emilmont | 1:fdd22bb7aa52 | 401 | { |
emilmont | 1:fdd22bb7aa52 | 402 | /* Read the input */ |
emilmont | 1:fdd22bb7aa52 | 403 | Xn = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 404 | |
emilmont | 1:fdd22bb7aa52 | 405 | /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 406 | |
emilmont | 1:fdd22bb7aa52 | 407 | /* acc = b0 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 408 | acc = (q63_t) Xn *b0; |
emilmont | 1:fdd22bb7aa52 | 409 | /* acc += b1 * x[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 410 | acc += (q63_t) Xn1 *b1; |
emilmont | 1:fdd22bb7aa52 | 411 | /* acc += b[2] * x[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 412 | acc += (q63_t) Xn2 *b2; |
emilmont | 1:fdd22bb7aa52 | 413 | /* acc += a1 * y[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 414 | acc += mult32x64(Yn1, a1); |
emilmont | 1:fdd22bb7aa52 | 415 | /* acc += a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 416 | acc += mult32x64(Yn2, a2); |
emilmont | 1:fdd22bb7aa52 | 417 | |
emilmont | 1:fdd22bb7aa52 | 418 | /* Every time after the output is computed state should be updated. */ |
emilmont | 1:fdd22bb7aa52 | 419 | /* The states should be updated as: */ |
emilmont | 1:fdd22bb7aa52 | 420 | /* Xn2 = Xn1 */ |
emilmont | 1:fdd22bb7aa52 | 421 | /* Xn1 = Xn */ |
emilmont | 1:fdd22bb7aa52 | 422 | /* Yn2 = Yn1 */ |
emilmont | 1:fdd22bb7aa52 | 423 | /* Yn1 = acc */ |
emilmont | 1:fdd22bb7aa52 | 424 | Xn2 = Xn1; |
emilmont | 1:fdd22bb7aa52 | 425 | Xn1 = Xn; |
emilmont | 1:fdd22bb7aa52 | 426 | Yn2 = Yn1; |
emilmont | 1:fdd22bb7aa52 | 427 | /* The result is converted to 1.63, Yn1 variable is reused */ |
emilmont | 1:fdd22bb7aa52 | 428 | Yn1 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 429 | |
emilmont | 1:fdd22bb7aa52 | 430 | /* Calc lower part of acc */ |
emilmont | 1:fdd22bb7aa52 | 431 | acc_l = acc & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 432 | |
emilmont | 1:fdd22bb7aa52 | 433 | /* Calc upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 434 | acc_h = (acc >> 32) & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 435 | |
emilmont | 1:fdd22bb7aa52 | 436 | /* Apply shift for lower part of acc and upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 437 | acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift; |
emilmont | 1:fdd22bb7aa52 | 438 | |
emilmont | 1:fdd22bb7aa52 | 439 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 440 | *pOut++ = acc_h; |
emilmont | 1:fdd22bb7aa52 | 441 | //Yn1 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 442 | |
emilmont | 1:fdd22bb7aa52 | 443 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 444 | // *pOut++ = (q31_t) (acc >> (32 - shift)); |
emilmont | 1:fdd22bb7aa52 | 445 | |
emilmont | 1:fdd22bb7aa52 | 446 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 447 | sample--; |
emilmont | 1:fdd22bb7aa52 | 448 | } |
emilmont | 1:fdd22bb7aa52 | 449 | |
emilmont | 1:fdd22bb7aa52 | 450 | /* The first stage output is given as input to the second stage. */ |
emilmont | 1:fdd22bb7aa52 | 451 | pIn = pDst; |
emilmont | 1:fdd22bb7aa52 | 452 | |
emilmont | 1:fdd22bb7aa52 | 453 | /* Reset to destination buffer working pointer */ |
emilmont | 1:fdd22bb7aa52 | 454 | pOut = pDst; |
emilmont | 1:fdd22bb7aa52 | 455 | |
emilmont | 1:fdd22bb7aa52 | 456 | /* Store the updated state variables back into the pState array */ |
emilmont | 1:fdd22bb7aa52 | 457 | /* Store the updated state variables back into the pState array */ |
emilmont | 1:fdd22bb7aa52 | 458 | *pState++ = (q63_t) Xn1; |
emilmont | 1:fdd22bb7aa52 | 459 | *pState++ = (q63_t) Xn2; |
emilmont | 1:fdd22bb7aa52 | 460 | *pState++ = Yn1; |
emilmont | 1:fdd22bb7aa52 | 461 | *pState++ = Yn2; |
emilmont | 1:fdd22bb7aa52 | 462 | |
emilmont | 1:fdd22bb7aa52 | 463 | } while(--stage); |
emilmont | 1:fdd22bb7aa52 | 464 | |
emilmont | 1:fdd22bb7aa52 | 465 | #else |
emilmont | 1:fdd22bb7aa52 | 466 | |
emilmont | 1:fdd22bb7aa52 | 467 | /* Run the below code for Cortex-M0 */ |
emilmont | 1:fdd22bb7aa52 | 468 | |
emilmont | 1:fdd22bb7aa52 | 469 | do |
emilmont | 1:fdd22bb7aa52 | 470 | { |
emilmont | 1:fdd22bb7aa52 | 471 | /* Reading the coefficients */ |
emilmont | 1:fdd22bb7aa52 | 472 | b0 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 473 | b1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 474 | b2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 475 | a1 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 476 | a2 = *pCoeffs++; |
emilmont | 1:fdd22bb7aa52 | 477 | |
emilmont | 1:fdd22bb7aa52 | 478 | /* Reading the state values */ |
emilmont | 1:fdd22bb7aa52 | 479 | Xn1 = pState[0]; |
emilmont | 1:fdd22bb7aa52 | 480 | Xn2 = pState[1]; |
emilmont | 1:fdd22bb7aa52 | 481 | Yn1 = pState[2]; |
emilmont | 1:fdd22bb7aa52 | 482 | Yn2 = pState[3]; |
emilmont | 1:fdd22bb7aa52 | 483 | |
emilmont | 1:fdd22bb7aa52 | 484 | /* The variable acc hold output value that is being computed and |
emilmont | 1:fdd22bb7aa52 | 485 | * stored in the destination buffer |
emilmont | 1:fdd22bb7aa52 | 486 | * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] |
emilmont | 1:fdd22bb7aa52 | 487 | */ |
emilmont | 1:fdd22bb7aa52 | 488 | |
emilmont | 1:fdd22bb7aa52 | 489 | sample = blockSize; |
emilmont | 1:fdd22bb7aa52 | 490 | |
emilmont | 1:fdd22bb7aa52 | 491 | while(sample > 0u) |
emilmont | 1:fdd22bb7aa52 | 492 | { |
emilmont | 1:fdd22bb7aa52 | 493 | /* Read the input */ |
emilmont | 1:fdd22bb7aa52 | 494 | Xn = *pIn++; |
emilmont | 1:fdd22bb7aa52 | 495 | |
emilmont | 1:fdd22bb7aa52 | 496 | /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 497 | /* acc = b0 * x[n] */ |
emilmont | 1:fdd22bb7aa52 | 498 | acc = (q63_t) Xn *b0; |
emilmont | 1:fdd22bb7aa52 | 499 | /* acc += b1 * x[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 500 | acc += (q63_t) Xn1 *b1; |
emilmont | 1:fdd22bb7aa52 | 501 | /* acc += b[2] * x[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 502 | acc += (q63_t) Xn2 *b2; |
emilmont | 1:fdd22bb7aa52 | 503 | /* acc += a1 * y[n-1] */ |
emilmont | 1:fdd22bb7aa52 | 504 | acc += mult32x64(Yn1, a1); |
emilmont | 1:fdd22bb7aa52 | 505 | /* acc += a2 * y[n-2] */ |
emilmont | 1:fdd22bb7aa52 | 506 | acc += mult32x64(Yn2, a2); |
emilmont | 1:fdd22bb7aa52 | 507 | |
emilmont | 1:fdd22bb7aa52 | 508 | /* Every time after the output is computed state should be updated. */ |
emilmont | 1:fdd22bb7aa52 | 509 | /* The states should be updated as: */ |
emilmont | 1:fdd22bb7aa52 | 510 | /* Xn2 = Xn1 */ |
emilmont | 1:fdd22bb7aa52 | 511 | /* Xn1 = Xn */ |
emilmont | 1:fdd22bb7aa52 | 512 | /* Yn2 = Yn1 */ |
emilmont | 1:fdd22bb7aa52 | 513 | /* Yn1 = acc */ |
emilmont | 1:fdd22bb7aa52 | 514 | Xn2 = Xn1; |
emilmont | 1:fdd22bb7aa52 | 515 | Xn1 = Xn; |
emilmont | 1:fdd22bb7aa52 | 516 | Yn2 = Yn1; |
emilmont | 1:fdd22bb7aa52 | 517 | |
emilmont | 1:fdd22bb7aa52 | 518 | /* The result is converted to 1.63, Yn1 variable is reused */ |
emilmont | 1:fdd22bb7aa52 | 519 | Yn1 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 520 | |
emilmont | 1:fdd22bb7aa52 | 521 | /* Calc lower part of acc */ |
emilmont | 1:fdd22bb7aa52 | 522 | acc_l = acc & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 523 | |
emilmont | 1:fdd22bb7aa52 | 524 | /* Calc upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 525 | acc_h = (acc >> 32) & 0xffffffff; |
emilmont | 1:fdd22bb7aa52 | 526 | |
emilmont | 1:fdd22bb7aa52 | 527 | /* Apply shift for lower part of acc and upper part of acc */ |
emilmont | 1:fdd22bb7aa52 | 528 | acc_h = (uint32_t) acc_l >> lShift | acc_h << uShift; |
emilmont | 1:fdd22bb7aa52 | 529 | |
emilmont | 1:fdd22bb7aa52 | 530 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 531 | *pOut++ = acc_h; |
emilmont | 1:fdd22bb7aa52 | 532 | |
emilmont | 1:fdd22bb7aa52 | 533 | //Yn1 = acc << shift; |
emilmont | 1:fdd22bb7aa52 | 534 | |
emilmont | 1:fdd22bb7aa52 | 535 | /* Store the output in the destination buffer in 1.31 format. */ |
emilmont | 1:fdd22bb7aa52 | 536 | //*pOut++ = (q31_t) (acc >> (32 - shift)); |
emilmont | 1:fdd22bb7aa52 | 537 | |
emilmont | 1:fdd22bb7aa52 | 538 | /* decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 539 | sample--; |
emilmont | 1:fdd22bb7aa52 | 540 | } |
emilmont | 1:fdd22bb7aa52 | 541 | |
emilmont | 1:fdd22bb7aa52 | 542 | /* The first stage output is given as input to the second stage. */ |
emilmont | 1:fdd22bb7aa52 | 543 | pIn = pDst; |
emilmont | 1:fdd22bb7aa52 | 544 | |
emilmont | 1:fdd22bb7aa52 | 545 | /* Reset to destination buffer working pointer */ |
emilmont | 1:fdd22bb7aa52 | 546 | pOut = pDst; |
emilmont | 1:fdd22bb7aa52 | 547 | |
emilmont | 1:fdd22bb7aa52 | 548 | /* Store the updated state variables back into the pState array */ |
emilmont | 1:fdd22bb7aa52 | 549 | *pState++ = (q63_t) Xn1; |
emilmont | 1:fdd22bb7aa52 | 550 | *pState++ = (q63_t) Xn2; |
emilmont | 1:fdd22bb7aa52 | 551 | *pState++ = Yn1; |
emilmont | 1:fdd22bb7aa52 | 552 | *pState++ = Yn2; |
emilmont | 1:fdd22bb7aa52 | 553 | |
emilmont | 1:fdd22bb7aa52 | 554 | } while(--stage); |
emilmont | 1:fdd22bb7aa52 | 555 | |
mbed_official | 3:7a284390b0ce | 556 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
emilmont | 1:fdd22bb7aa52 | 557 | } |
emilmont | 1:fdd22bb7aa52 | 558 | |
emilmont | 1:fdd22bb7aa52 | 559 | /** |
emilmont | 1:fdd22bb7aa52 | 560 | * @} end of BiquadCascadeDF1_32x64 group |
emilmont | 1:fdd22bb7aa52 | 561 | */ |