diff options
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df1_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df1_f32.c | 585 |
1 files changed, 334 insertions, 251 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df1_f32.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df1_f32.c index 0ffb29ee7..d28509d4c 100644 --- a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df1_f32.c +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_biquad_cascade_df1_f32.c @@ -3,13 +3,13 @@ * Title: arm_biquad_cascade_df1_f32.c * Description: Processing function for the floating-point Biquad cascade DirectFormI(DF1) filter * - * $Date: 27. January 2017 - * $Revision: V.1.5.1 + * $Date: 18. March 2019 + * $Revision: V1.6.0 * * Target Processor: Cortex-M cores * -------------------------------------------------------------------- */ /* - * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. + * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. * * SPDX-License-Identifier: Apache-2.0 * @@ -29,159 +29,308 @@ #include "arm_math.h" /** - * @ingroup groupFilters + @ingroup groupFilters */ /** - * @defgroup BiquadCascadeDF1 Biquad Cascade IIR Filters Using Direct Form I Structure - * - * This set of functions implements arbitrary order recursive (IIR) filters. - * The filters are implemented as a cascade of second order Biquad sections. - * The functions support Q15, Q31 and floating-point data types. - * Fast version of Q15 and Q31 also supported on CortexM4 and Cortex-M3. - * - * The functions 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] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] - * </pre> - * A Direct Form I algorithm is used with 5 coefficients and 4 state variables per stage. - * \image html Biquad.gif "Single Biquad filter stage" - * 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 use the difference equation - * <pre> - * y[n] = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] - a1 * y[n-1] - a2 * y[n-2] - * </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. - * \image html BiquadCascade.gif "8th order filter using a cascade of Biquad 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 - * The <code>pState</code> points to state variables array. - * Each Biquad stage has 4 state variables <code>x[n-1], x[n-2], y[n-1],</code> and <code>y[n-2]</code>. - * The state variables are arranged in the <code>pState</code> array as: - * <pre> - * {x[n-1], x[n-2], y[n-1], y[n-2]} - * </pre> - * - * \par - * The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on. - * The state array has a total length of <code>4*numStages</code> values. - * The state variables are updated after each block of data is processed, the coefficients are untouched. - * - * \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. - * There are separate instance structure declarations for each of the 3 supported data types. - * - * \par Init Functions - * There is also an associated initialization function for each data type. - * 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. - * The code below statically initializes each of the 3 different data type filter instance structures - * <pre> - * arm_biquad_casd_df1_inst_f32 S1 = {numStages, pState, pCoeffs}; - * arm_biquad_casd_df1_inst_q15 S2 = {numStages, pState, pCoeffs, postShift}; - * arm_biquad_casd_df1_inst_q31 S3 = {numStages, pState, pCoeffs, postShift}; - * </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; <code>postShift</code> shift to be applied. - * - * \par Fixed-Point Behavior - * Care must be taken when using the Q15 and Q31 versions of the Biquad Cascade filter functions. - * Following issues must be considered: - * - Scaling of coefficients - * - Filter gain - * - Overflow and saturation - * - * \par - * <b>Scaling of coefficients: </b> - * Filter coefficients are represented as fractional values and - * coefficients are restricted to lie in the range <code>[-1 +1)</code>. - * The fixed-point functions have an additional scaling parameter <code>postShift</code> - * which allow the filter coefficients to exceed the range <code>[+1 -1)</code>. - * At the output of the filter's accumulator is a shift register which shifts the result by <code>postShift</code> bits. - * \image html BiquadPostshift.gif "Fixed-point Biquad with shift by postShift bits after accumulator" - * This essentially scales the filter coefficients by <code>2^postShift</code>. - * For example, to realize the coefficients - * <pre> - * {1.5, -0.8, 1.2, 1.6, -0.9} - * </pre> - * set the pCoeffs array to: - * <pre> - * {0.75, -0.4, 0.6, 0.8, -0.45} - * </pre> - * and set <code>postShift=1</code> - * - * \par - * <b>Filter gain: </b> - * The frequency response of a Biquad filter is a function of its coefficients. - * It is possible for the gain through the filter to exceed 1.0 meaning that the filter increases the amplitude of certain frequencies. - * 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. - * 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. - * - * \par - * <b>Overflow and saturation: </b> - * For Q15 and Q31 versions, it is described separately as part of the function specific documentation below. + @defgroup BiquadCascadeDF1 Biquad Cascade IIR Filters Using Direct Form I Structure + + This set of functions implements arbitrary order recursive (IIR) filters. + The filters are implemented as a cascade of second order Biquad sections. + The functions support Q15, Q31 and floating-point data types. + Fast version of Q15 and Q31 also available. + + The functions 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] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + </pre> + A Direct Form I algorithm is used with 5 coefficients and 4 state variables per stage. + \image html Biquad.gif "Single Biquad filter stage" + 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 use the difference equation + <pre> + y[n] = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] - a1 * y[n-1] - a2 * y[n-2] + </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. + \image html BiquadCascade.gif "8th order filter using a cascade of Biquad 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 + The <code>pState</code> points to state variables array. + Each Biquad stage has 4 state variables <code>x[n-1], x[n-2], y[n-1],</code> and <code>y[n-2]</code>. + The state variables are arranged in the <code>pState</code> array as: + <pre> + {x[n-1], x[n-2], y[n-1], y[n-2]} + </pre> + + @par + The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on. + The state array has a total length of <code>4*numStages</code> values. + The state variables are updated after each block of data is processed, the coefficients are untouched. + + @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. + There are separate instance structure declarations for each of the 3 supported data types. + + @par Init Function + There is also an associated initialization function for each data type. + 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. + The code below statically initializes each of the 3 different data type filter instance structures + <pre> + arm_biquad_casd_df1_inst_f32 S1 = {numStages, pState, pCoeffs}; + arm_biquad_casd_df1_inst_q15 S2 = {numStages, pState, pCoeffs, postShift}; + arm_biquad_casd_df1_inst_q31 S3 = {numStages, pState, pCoeffs, postShift}; + </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; + <code>postShift</code> shift to be applied. + + @par Fixed-Point Behavior + Care must be taken when using the Q15 and Q31 versions of the Biquad Cascade filter functions. + Following issues must be considered: + - Scaling of coefficients + - Filter gain + - Overflow and saturation + + @par Scaling of coefficients + Filter coefficients are represented as fractional values and + coefficients are restricted to lie in the range <code>[-1 +1)</code>. + The fixed-point functions have an additional scaling parameter <code>postShift</code> + which allow the filter coefficients to exceed the range <code>[+1 -1)</code>. + At the output of the filter's accumulator is a shift register which shifts the result by <code>postShift</code> bits. + \image html BiquadPostshift.gif "Fixed-point Biquad with shift by postShift bits after accumulator" + This essentially scales the filter coefficients by <code>2^postShift</code>. + For example, to realize the coefficients + <pre> + {1.5, -0.8, 1.2, 1.6, -0.9} + </pre> + set the pCoeffs array to: + <pre> + {0.75, -0.4, 0.6, 0.8, -0.45} + </pre> + and set <code>postShift=1</code> + + @par Filter gain + The frequency response of a Biquad filter is a function of its coefficients. + It is possible for the gain through the filter to exceed 1.0 meaning that the filter increases the amplitude of certain frequencies. + 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. + 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. + + @par Overflow and saturation + For Q15 and Q31 versions, it is described separately as part of the function specific documentation below. */ /** - * @addtogroup BiquadCascadeDF1 - * @{ + @addtogroup BiquadCascadeDF1 + @{ */ /** - * @param[in] *S points to an instance of the floating-point Biquad cascade 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 per call. - * @return none. - * + @brief Processing function for the floating-point Biquad cascade filter. + @param[in] S points to an instance of the floating-point Biquad cascade 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 */ +#if defined(ARM_MATH_NEON) void arm_biquad_cascade_df1_f32( const arm_biquad_casd_df1_inst_f32 * S, - float32_t * pSrc, + const float32_t * pSrc, float32_t * pDst, uint32_t blockSize) { - float32_t *pIn = pSrc; /* source pointer */ + + const float32_t *pIn = pSrc; /* source pointer */ float32_t *pOut = pDst; /* destination pointer */ float32_t *pState = S->pState; /* pState pointer */ - float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */ + const float32_t *pCoeffs = S->pCoeffs; /* coefficient pointer */ float32_t acc; /* Simulates the accumulator */ - float32_t b0, b1, b2, a1, a2; /* Filter coefficients */ - float32_t Xn1, Xn2, Yn1, Yn2; /* Filter pState variables */ - float32_t Xn; /* temporary input */ + uint32_t sample, stage = S->numStages; /* loop counters */ + float32x4_t Xn; + float32x2_t Yn; + float32x2_t a; + float32x4_t b; + + float32x4_t x,tmp; + float32x2_t t; + float32x2x2_t y; + + float32_t Xns; + + while (stage > 0U) + { + /* Reading the coefficients */ + Xn = vld1q_f32(pState); + Yn = vld1_f32(pState + 2); + + b = vld1q_f32(pCoeffs); + b = vrev64q_f32(b); + b = vcombine_f32(vget_high_f32(b), vget_low_f32(b)); + + a = vld1_f32(pCoeffs + 3); + a = vrev64_f32(a); + b[0] = 0.0; + pCoeffs += 5; + + /* Reading the pState values */ + + /* Apply loop unrolling and compute 4 output values simultaneously. */ + /* The variable acc hold output values that are being computed: + * + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + */ + + /* 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. */ + sample = blockSize >> 2U; + + while (sample > 0U) + { + /* Read the first 4 inputs */ + x = vld1q_f32(pIn); + + pIn += 4; + + tmp = vextq_f32(Xn, x, 1); + t = vmul_f32(vget_high_f32(b), vget_high_f32(tmp)); + t = vmla_f32(t, vget_low_f32(b), vget_low_f32(tmp)); + t = vmla_f32(t, a, Yn); + t = vpadd_f32(t, t); + Yn = vext_f32(Yn, t, 1); + + tmp = vextq_f32(Xn, x, 2); + t = vmul_f32(vget_high_f32(b), vget_high_f32(tmp)); + t = vmla_f32(t, vget_low_f32(b), vget_low_f32(tmp)); + t = vmla_f32(t, a, Yn); + t = vpadd_f32(t, t); + Yn = vext_f32(Yn, t, 1); + + y.val[0] = Yn; + + tmp = vextq_f32(Xn, x, 3); + t = vmul_f32(vget_high_f32(b), vget_high_f32(tmp)); + t = vmla_f32(t, vget_low_f32(b), vget_low_f32(tmp)); + t = vmla_f32(t, a, Yn); + t = vpadd_f32(t, t); + Yn = vext_f32(Yn, t, 1); + + Xn = x; + t = vmul_f32(vget_high_f32(b), vget_high_f32(Xn)); + t = vmla_f32(t, vget_low_f32(b), vget_low_f32(Xn)); + t = vmla_f32(t, a, Yn); + t = vpadd_f32(t, t); + Yn = vext_f32(Yn, t, 1); + + y.val[1] = Yn; + + tmp = vcombine_f32(y.val[0], y.val[1]); + + /* Store the 4 outputs and increment the pointer */ + vst1q_f32(pOut, tmp); + pOut += 4; + + /* Decrement the loop counter */ + sample--; + } + + /* If the block size is not a multiple of 4, compute any remaining output samples here. + ** No loop unrolling is used. */ + sample = blockSize & 0x3U; + + while (sample > 0U) + { + /* Read the input */ + Xns = *pIn++; + + /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ + acc = (b[1] * Xn[2]) + (b[2] * Xn[3]) + (b[3] * Xns) + (a[0] * Yn[0]) + (a[1] * Yn[1]); + + /* Store the result in the accumulator in the destination buffer. */ + *pOut++ = acc; + + /* Every time after the output is computed state should be updated. */ + /* The states should be updated as: */ + /* Xn2 = Xn1 */ + /* Xn1 = Xn */ + /* Yn2 = Yn1 */ + /* Yn1 = acc */ + Xn[2] = Xn[3]; + Xn[3] = Xns; + Yn[0] = Yn[1]; + Yn[1] = acc; + + /* Decrement the loop counter */ + sample--; -#if defined (ARM_MATH_DSP) + } + + vst1q_f32(pState,vcombine_f32(vrev64_f32(vget_high_f32(Xn)),vrev64_f32(Yn))); + pState += 4; + /* Store the updated state variables back into the pState array */ + + /* The first stage goes from the input buffer to the output buffer. */ + /* Subsequent numStages occur in-place in the output buffer */ + pIn = pDst; - /* Run the below code for Cortex-M4 and Cortex-M3 */ + /* Reset the output pointer */ + pOut = pDst; + + /* Decrement the loop counter */ + stage--; + } +} + +#else +void arm_biquad_cascade_df1_f32( + const arm_biquad_casd_df1_inst_f32 * S, + const float32_t * pSrc, + float32_t * pDst, + uint32_t blockSize) +{ + const float32_t *pIn = pSrc; /* Source pointer */ + float32_t *pOut = pDst; /* Destination pointer */ + float32_t *pState = S->pState; /* pState pointer */ + const float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ + float32_t acc; /* Accumulator */ + float32_t b0, b1, b2, a1, a2; /* Filter coefficients */ + float32_t Xn1, Xn2, Yn1, Yn2; /* Filter pState variables */ + float32_t Xn; /* Temporary input */ + uint32_t sample, stage = S->numStages; /* Loop counters */ do { @@ -198,19 +347,20 @@ void arm_biquad_cascade_df1_f32( Yn1 = pState[2]; Yn2 = pState[3]; +#if defined (ARM_MATH_LOOPUNROLL) + /* Apply loop unrolling and compute 4 output values simultaneously. */ - /* The variable acc hold output values that are being computed: + /* Variable acc hold output values that are being computed: * - * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] - * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] - * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] - * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] + * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ + /* Loop unrolling: Compute 4 outputs at a time */ 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) { /* Read the first input */ @@ -219,15 +369,15 @@ void arm_biquad_cascade_df1_f32( /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ Yn2 = (b0 * Xn) + (b1 * Xn1) + (b2 * Xn2) + (a1 * Yn1) + (a2 * Yn2); - /* Store the result in the accumulator in the destination buffer. */ + /* Store output in destination buffer. */ *pOut++ = Yn2; /* Every time after the output is computed state should be updated. */ - /* The states should be updated as: */ - /* Xn2 = Xn1 */ - /* Xn1 = Xn */ - /* Yn2 = Yn1 */ - /* Yn1 = acc */ + /* The states should be updated as: */ + /* Xn2 = Xn1 */ + /* Xn1 = Xn */ + /* Yn2 = Yn1 */ + /* Yn1 = acc */ /* Read the second input */ Xn2 = *pIn++; @@ -235,15 +385,15 @@ void arm_biquad_cascade_df1_f32( /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ Yn1 = (b0 * Xn2) + (b1 * Xn) + (b2 * Xn1) + (a1 * Yn2) + (a2 * Yn1); - /* Store the result in the accumulator in the destination buffer. */ + /* Store output in destination buffer. */ *pOut++ = Yn1; /* Every time after the output is computed state should be updated. */ - /* The states should be updated as: */ - /* Xn2 = Xn1 */ - /* Xn1 = Xn */ - /* Yn2 = Yn1 */ - /* Yn1 = acc */ + /* The states should be updated as: */ + /* Xn2 = Xn1 */ + /* Xn1 = Xn */ + /* Yn2 = Yn1 */ + /* Yn1 = acc */ /* Read the third input */ Xn1 = *pIn++; @@ -251,15 +401,15 @@ void arm_biquad_cascade_df1_f32( /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ Yn2 = (b0 * Xn1) + (b1 * Xn2) + (b2 * Xn) + (a1 * Yn1) + (a2 * Yn2); - /* Store the result in the accumulator in the destination buffer. */ + /* Store output in destination buffer. */ *pOut++ = Yn2; /* Every time after the output is computed state should be updated. */ /* The states should be updated as: */ - /* Xn2 = Xn1 */ - /* Xn1 = Xn */ - /* Yn2 = Yn1 */ - /* Yn1 = acc */ + /* Xn2 = Xn1 */ + /* Xn1 = Xn */ + /* Yn2 = Yn1 */ + /* Yn1 = acc */ /* Read the forth input */ Xn = *pIn++; @@ -267,97 +417,32 @@ void arm_biquad_cascade_df1_f32( /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ Yn1 = (b0 * Xn) + (b1 * Xn1) + (b2 * Xn2) + (a1 * Yn2) + (a2 * Yn1); - /* Store the result in the accumulator in the destination buffer. */ + /* Store output in destination buffer. */ *pOut++ = Yn1; /* Every time after the output is computed state should be updated. */ - /* The states should be updated as: */ - /* Xn2 = Xn1 */ - /* Xn1 = Xn */ - /* Yn2 = Yn1 */ - /* Yn1 = acc */ + /* The states should be updated as: */ + /* Xn2 = Xn1 */ + /* Xn1 = Xn */ + /* Yn2 = Yn1 */ + /* Yn1 = acc */ Xn2 = Xn1; Xn1 = Xn; - /* decrement the loop counter */ + /* decrement loop counter */ sample--; - } - /* If the blockSize is not a multiple of 4, compute any remaining output samples here. - ** No loop unrolling is used. */ + /* Loop unrolling: Compute remaining outputs */ sample = blockSize & 0x3U; - while (sample > 0U) - { - /* Read the input */ - Xn = *pIn++; - - /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ - acc = (b0 * Xn) + (b1 * Xn1) + (b2 * Xn2) + (a1 * Yn1) + (a2 * Yn2); - - /* Store the result in the accumulator in the destination buffer. */ - *pOut++ = acc; - - /* Every time after the output is computed state should be updated. */ - /* The states should be updated as: */ - /* Xn2 = Xn1 */ - /* Xn1 = Xn */ - /* Yn2 = Yn1 */ - /* Yn1 = acc */ - Xn2 = Xn1; - Xn1 = Xn; - Yn2 = Yn1; - Yn1 = acc; - - /* decrement the loop counter */ - sample--; - - } - - /* Store the updated state variables back into the pState array */ - *pState++ = Xn1; - *pState++ = Xn2; - *pState++ = Yn1; - *pState++ = Yn2; - - /* The first stage goes from the input buffer to the output buffer. */ - /* Subsequent numStages occur in-place in the output buffer */ - pIn = pDst; - - /* Reset the output 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 pState values */ - Xn1 = pState[0]; - Xn2 = pState[1]; - Yn1 = pState[2]; - Yn2 = pState[3]; - - /* The variables acc holds the output value that is computed: - * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] - */ - + /* Initialize blkCnt with number of samples */ sample = blockSize; +#endif /* #if defined (ARM_MATH_LOOPUNROLL) */ + while (sample > 0U) { /* Read the input */ @@ -366,47 +451,45 @@ void arm_biquad_cascade_df1_f32( /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ acc = (b0 * Xn) + (b1 * Xn1) + (b2 * Xn2) + (a1 * Yn1) + (a2 * Yn2); - /* Store the result in the accumulator in the destination buffer. */ + /* Store output in destination buffer. */ *pOut++ = acc; /* Every time after the output is computed state should be updated. */ - /* The states should be updated as: */ - /* Xn2 = Xn1 */ - /* Xn1 = Xn */ - /* Yn2 = Yn1 */ - /* Yn1 = acc */ + /* The states should be updated as: */ + /* Xn2 = Xn1 */ + /* Xn1 = Xn */ + /* Yn2 = Yn1 */ + /* Yn1 = acc */ Xn2 = Xn1; Xn1 = Xn; Yn2 = Yn1; Yn1 = acc; - /* decrement the loop counter */ + /* decrement loop counter */ sample--; } - /* Store the updated state variables back into the pState array */ + /* Store the updated state variables back into the pState array */ *pState++ = Xn1; *pState++ = Xn2; *pState++ = Yn1; *pState++ = Yn2; - /* The first stage goes from the input buffer to the output buffer. */ - /* Subsequent numStages occur in-place in the output buffer */ + /* The first stage goes from the input buffer to the output buffer. */ + /* Subsequent numStages occur in-place in the output buffer */ pIn = pDst; - /* Reset the output pointer */ + /* Reset output pointer */ pOut = pDst; - /* decrement the loop counter */ + /* decrement loop counter */ stage--; } while (stage > 0U); -#endif /* #if defined (ARM_MATH_DSP) */ - } - - /** - * @} end of BiquadCascadeDF1 group - */ +#endif /* #if defined(ARM_MATH_NEON) */ +/** + @} end of BiquadCascadeDF1 group + */ |