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Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df2T_f64.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df2T_f64.c | 443 |
1 files changed, 443 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df2T_f64.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df2T_f64.c new file mode 100644 index 0000000..3d527a0 --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df2T_f64.c @@ -0,0 +1,443 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_biquad_cascade_df2T_f64.c
+ * Description: Processing function for floating-point transposed direct form II Biquad cascade filter
+ *
+ * $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"
+
+/**
+ @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_f64 S1 = {numStages, pState, pCoeffs};
+ 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_df2T_f64(
+ const arm_biquad_cascade_df2T_instance_f64 * S,
+ float64_t * pSrc,
+ float64_t * pDst,
+ uint32_t blockSize)
+{
+
+ float64_t *pIn = pSrc; /* Source pointer */
+ float64_t *pOut = pDst; /* Destination pointer */
+ float64_t *pState = S->pState; /* State pointer */
+ float64_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ float64_t acc1; /* Accumulator */
+ float64_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ float64_t Xn1; /* Temporary input */
+ float64_t d1, d2; /* State variables */
+ uint32_t sample, stage = S->numStages; /* Loop counters */
+
+
+ do
+ {
+ /* Reading the coefficients */
+ b0 = pCoeffs[0];
+ b1 = pCoeffs[1];
+ b2 = pCoeffs[2];
+ a1 = pCoeffs[3];
+ a2 = pCoeffs[4];
+
+ /* Reading the state values */
+ d1 = pState[0];
+ d2 = pState[1];
+
+ pCoeffs += 5U;
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 16 outputs at a time */
+ sample = blockSize >> 4U;
+
+ while (sample > 0U) {
+
+ /* y[n] = b0 * x[n] + d1 */
+ /* d1 = b1 * x[n] + a1 * y[n] + d2 */
+ /* d2 = b2 * x[n] + a2 * y[n] */
+
+/* 1 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+
+/* 2 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 3 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 4 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 5 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 6 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 7 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 8 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 9 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 10 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 11 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 12 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 13 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 14 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 15 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+/* 16 */
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+ /* decrement loop counter */
+ sample--;
+ }
+
+ /* Loop unrolling: Compute remaining outputs */
+ sample = blockSize & 0xFU;
+
+#else
+
+ /* Initialize blkCnt with number of samples */
+ sample = blockSize;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (sample > 0U) {
+ Xn1 = *pIn++;
+
+ acc1 = b0 * Xn1 + d1;
+
+ d1 = b1 * Xn1 + d2;
+ d1 += a1 * acc1;
+
+ d2 = b2 * Xn1;
+ d2 += a2 * acc1;
+
+ *pOut++ = acc1;
+
+ /* decrement loop counter */
+ sample--;
+ }
+
+ /* Store the updated state variables back into the state array */
+ pState[0] = d1;
+ pState[1] = d2;
+
+ pState += 2U;
+
+ /* The current stage input is given as the output to the next stage */
+ pIn = pDst;
+
+ /* Reset the output working pointer */
+ pOut = pDst;
+
+ /* decrement loop counter */
+ stage--;
+
+ } while (stage > 0U);
+
+}
+LOW_OPTIMIZATION_EXIT
+
+/**
+ @} end of BiquadCascadeDF2T group
+ */
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