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Diffstat (limited to 'tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df2T_f32.c')
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diff --git a/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df2T_f32.c b/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df2T_f32.c new file mode 100644 index 0000000000..1462d51e7b --- /dev/null +++ b/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FilteringFunctions/arm_biquad_cascade_df2T_f32.c @@ -0,0 +1,359 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2013 ARM Limited. All rights reserved. +* +* $Date: 17. January 2013 +* +* Project: CMSIS DSP Library +* Title: arm_biquad_cascade_df2T_f32.c +* +* Description: Processing function for the floating-point transposed +* direct form II Biquad cascade filter. +* +* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 +* +* Redistribution and use in source and binary forms, with or without +* modification, are permitted provided that the following conditions +* are met: +* - Redistributions of source code must retain the above copyright +* notice, this list of conditions and the following disclaimer. +* - Redistributions in binary form must reproduce the above copyright +* notice, this list of conditions and the following disclaimer in +* the documentation and/or other materials provided with the +* distribution. +* - Neither the name of ARM LIMITED nor the names of its contributors +* may be used to endorse or promote products derived from this +* software without specific prior written permission. +* +* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, +* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +* POSSIBILITY OF SUCH DAMAGE. +* -------------------------------------------------------------------- */ + +#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_df2T_f32( +const arm_biquad_cascade_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 acc1; /* accumulator */ + float32_t b0, b1, b2, a1, a2; /* Filter coefficients */ + float32_t Xn1; /* temporary input */ + float32_t d1, d2; /* state variables */ + uint32_t sample, stage = S->numStages; /* loop counters */ + +#ifndef ARM_MATH_CM0_FAMILY_FAMILY + + float32_t Xn2, Xn3, Xn4; /* Input State variables */ + float32_t acc2, acc3, acc4; /* accumulator */ + + + float32_t p0, p1, p2, p3, p4, A1; + + /* 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 */ + d1 = pState[0]; + d2 = pState[1]; + + /* 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 */ + Xn1 = pIn[0]; + Xn2 = pIn[1]; + Xn3 = pIn[2]; + Xn4 = pIn[3]; + pIn += 4; + + p0 = b0 * Xn1; + p1 = b1 * Xn1; + acc1 = p0 + d1; + p0 = b0 * Xn2; + p3 = a1 * acc1; + p2 = b2 * Xn1; + A1 = p1 + p3; + p4 = a2 * acc1; + d1 = A1 + d2; + d2 = p2 + p4; + + p1 = b1 * Xn2; + acc2 = p0 + d1; + p0 = b0 * Xn3; + p3 = a1 * acc2; + p2 = b2 * Xn2; + A1 = p1 + p3; + p4 = a2 * acc2; + d1 = A1 + d2; + d2 = p2 + p4; + + p1 = b1 * Xn3; + acc3 = p0 + d1; + p0 = b0 * Xn4; + p3 = a1 * acc3; + p2 = b2 * Xn3; + A1 = p1 + p3; + p4 = a2 * acc3; + d1 = A1 + d2; + d2 = p2 + p4; + + acc4 = p0 + d1; + p1 = b1 * Xn4; + p3 = a1 * acc4; + p2 = b2 * Xn4; + A1 = p1 + p3; + p4 = a2 * acc4; + d1 = A1 + d2; + d2 = p2 + p4; + + pOut[0] = acc1; + pOut[1] = acc2; + pOut[2] = acc3; + pOut[3] = acc4; + pOut += 4; + + sample--; + } + + sample = blockSize & 0x3u; + while(sample > 0u) { + Xn1 = *pIn++; + + p0 = b0 * Xn1; + p1 = b1 * Xn1; + acc1 = p0 + d1; + p3 = a1 * acc1; + p2 = b2 * Xn1; + A1 = p1 + p3; + p4 = a2 * acc1; + d1 = A1 + d2; + d2 = p2 + p4; + + *pOut++ = acc1; + + sample--; + } + + /* Store the updated state variables back into the state array */ + *pState++ = d1; + *pState++ = d2; + + /* 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 + + /* 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 */ + d1 = pState[0]; + d2 = pState[1]; + + + sample = blockSize; + + while(sample > 0u) + { + /* Read the input */ + Xn1 = *pIn++; + + /* y[n] = b0 * x[n] + d1 */ + acc1 = (b0 * Xn1) + d1; + + /* Store the result in the accumulator in the destination buffer. */ + *pOut++ = acc1; + + /* Every time after the output is computed state should be updated. */ + /* d1 = b1 * x[n] + a1 * y[n] + d2 */ + d1 = ((b1 * Xn1) + (a1 * acc1)) + d2; + + /* d2 = b2 * x[n] + a2 * y[n] */ + d2 = (b2 * Xn1) + (a2 * acc1); + + /* decrement the loop counter */ + sample--; + } + + /* Store the updated state variables back into the state array */ + *pState++ = d1; + *pState++ = d2; + + /* 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 /* #ifndef ARM_MATH_CM0_FAMILY */ + +} +LOW_OPTIMIZATION_EXIT + +/** + * @} end of BiquadCascadeDF2T group + */ |