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Diffstat (limited to 'DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c')
-rw-r--r-- | DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c b/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c new file mode 100644 index 0000000..b135b2e --- /dev/null +++ b/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c @@ -0,0 +1,305 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 19. October 2015 +* $Revision: V.1.4.5 a +* +* Project: CMSIS DSP Library +* Title: arm_biquad_cascade_df1_fast_q31.c +* +* Description: Processing function for the +* Q31 Fast Biquad cascade DirectFormI(DF1) filter. +* +* Target Processor: Cortex-M4/Cortex-M3 +* +* 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 + */ + +/** + * @addtogroup BiquadCascadeDF1 + * @{ + */ + +/** + * @details + * + * @param[in] *S points to an instance of the Q31 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. + * + * <b>Scaling and Overflow Behavior:</b> + * \par + * This function is optimized for speed at the expense of fixed-point precision and overflow protection. + * The result of each 1.31 x 1.31 multiplication is truncated to 2.30 format. + * These intermediate results are added to a 2.30 accumulator. + * Finally, the accumulator is saturated and converted to a 1.31 result. + * The fast version has the same overflow behavior as the standard version and provides less precision since it discards the low 32 bits of each multiplication result. + * In order to avoid overflows completely the input signal must be scaled down by two bits and lie in the range [-0.25 +0.25). Use the intialization function + * arm_biquad_cascade_df1_init_q31() to initialize filter structure. + * + * \par + * Refer to the function <code>arm_biquad_cascade_df1_q31()</code> for a slower implementation of this function which uses 64-bit accumulation to provide higher precision. Both the slow and the fast versions use the same instance structure. + * Use the function <code>arm_biquad_cascade_df1_init_q31()</code> to initialize the filter structure. + */ + +void arm_biquad_cascade_df1_fast_q31( + const arm_biquad_casd_df1_inst_q31 * S, + q31_t * pSrc, + q31_t * pDst, + uint32_t blockSize) +{ + q31_t acc = 0; /* accumulator */ + q31_t Xn1, Xn2, Yn1, Yn2; /* Filter state variables */ + q31_t b0, b1, b2, a1, a2; /* Filter coefficients */ + q31_t *pIn = pSrc; /* input pointer initialization */ + q31_t *pOut = pDst; /* output pointer initialization */ + q31_t *pState = S->pState; /* pState pointer initialization */ + q31_t *pCoeffs = S->pCoeffs; /* coeff pointer initialization */ + q31_t Xn; /* temporary input */ + int32_t shift = (int32_t) S->postShift + 1; /* Shift to be applied to the output */ + uint32_t sample, stage = S->numStages; /* loop counters */ + + + do + { + /* Reading the coefficients */ + b0 = *pCoeffs++; + b1 = *pCoeffs++; + b2 = *pCoeffs++; + a1 = *pCoeffs++; + a2 = *pCoeffs++; + + /* Reading the state values */ + Xn1 = pState[0]; + Xn2 = pState[1]; + Yn1 = pState[2]; + Yn2 = pState[3]; + + /* Apply loop unrolling and compute 4 output values simultaneously. */ + /* The variables acc ... acc3 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] + */ + + 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 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 * x[n] */ + /*acc = (q31_t) (((q63_t) b1 * Xn1) >> 32);*/ + mult_32x32_keep32_R(acc, b1, Xn1); + /* acc += b1 * x[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b0 * (Xn))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b0, Xn); + /* acc += b[2] * x[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b2, Xn2); + /* acc += a1 * y[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a1, Yn1); + /* acc += a2 * y[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a2, Yn2); + + /* The result is converted to 1.31 , Yn2 variable is reused */ + Yn2 = acc << shift; + + /* Read the second input */ + Xn2 = *(pIn + 1u); + + /* Store the output in the destination buffer. */ + *pOut = Yn2; + + /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ + /* acc = b0 * x[n] */ + /*acc = (q31_t) (((q63_t) b0 * (Xn2)) >> 32);*/ + mult_32x32_keep32_R(acc, b0, Xn2); + /* acc += b1 * x[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b1, Xn); + /* acc += b[2] * x[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b2, Xn1); + /* acc += a1 * y[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a1, Yn2); + /* acc += a2 * y[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a2, Yn1); + + /* The result is converted to 1.31, Yn1 variable is reused */ + Yn1 = acc << shift; + + /* Read the third input */ + Xn1 = *(pIn + 2u); + + /* Store the output in the destination buffer. */ + *(pOut + 1u) = Yn1; + + /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ + /* acc = b0 * x[n] */ + /*acc = (q31_t) (((q63_t) b0 * (Xn1)) >> 32);*/ + mult_32x32_keep32_R(acc, b0, Xn1); + /* acc += b1 * x[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b1, Xn2); + /* acc += b[2] * x[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b2, Xn); + /* acc += a1 * y[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a1, Yn1); + /* acc += a2 * y[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a2, Yn2); + + /* The result is converted to 1.31, Yn2 variable is reused */ + Yn2 = acc << shift; + + /* Read the forth input */ + Xn = *(pIn + 3u); + + /* Store the output in the destination buffer. */ + *(pOut + 2u) = Yn2; + pIn += 4u; + + /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ + /* acc = b0 * x[n] */ + /*acc = (q31_t) (((q63_t) b0 * (Xn)) >> 32);*/ + mult_32x32_keep32_R(acc, b0, Xn); + /* acc += b1 * x[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b1, Xn1); + /* acc += b[2] * x[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b2, Xn2); + /* acc += a1 * y[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a1, Yn2); + /* acc += a2 * y[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a2, Yn1); + + /* Every time after the output is computed state should be updated. */ + /* The states should be updated as: */ + /* Xn2 = Xn1 */ + Xn2 = Xn1; + + /* The result is converted to 1.31, Yn1 variable is reused */ + Yn1 = acc << shift; + + /* Xn1 = Xn */ + Xn1 = Xn; + + /* Store the output in the destination buffer. */ + *(pOut + 3u) = Yn1; + pOut += 4u; + + /* decrement the loop counter */ + sample--; + } + + /* If the blockSize 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 */ + Xn = *pIn++; + + /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */ + /* acc = b0 * x[n] */ + /*acc = (q31_t) (((q63_t) b0 * (Xn)) >> 32);*/ + mult_32x32_keep32_R(acc, b0, Xn); + /* acc += b1 * x[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b1, Xn1); + /* acc += b[2] * x[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, b2, Xn2); + /* acc += a1 * y[n-1] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a1, Yn1); + /* acc += a2 * y[n-2] */ + /*acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);*/ + multAcc_32x32_keep32_R(acc, a2, Yn2); + + /* The result is converted to 1.31 */ + acc = acc << shift; + + /* 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; + + /* Store the output in the destination buffer. */ + *pOut++ = acc; + + /* decrement the loop counter */ + sample--; + } + + /* The first stage goes from the input buffer to the output buffer. */ + /* Subsequent stages occur in-place in the output buffer */ + pIn = pDst; + + /* Reset to destination pointer */ + pOut = pDst; + + /* Store the updated state variables back into the pState array */ + *pState++ = Xn1; + *pState++ = Xn2; + *pState++ = Yn1; + *pState++ = Yn2; + + } while(--stage); +} + +/** + * @} end of BiquadCascadeDF1 group + */ |