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Diffstat (limited to 'platform/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_iir_lattice_q31.c')
| -rw-r--r-- | platform/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_iir_lattice_q31.c | 350 |
1 files changed, 350 insertions, 0 deletions
diff --git a/platform/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_iir_lattice_q31.c b/platform/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_iir_lattice_q31.c new file mode 100644 index 0000000..23ff79f --- /dev/null +++ b/platform/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_iir_lattice_q31.c @@ -0,0 +1,350 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 12. March 2014 +* $Revision: V1.4.4 +* +* Project: CMSIS DSP Library +* Title: arm_iir_lattice_q31.c +* +* Description: Q31 IIR lattice filter processing function. +* +* 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 + */ + +/** + * @addtogroup IIR_Lattice + * @{ + */ + +/** + * @brief Processing function for the Q31 IIR lattice filter. + * @param[in] *S points to an instance of the Q31 IIR lattice 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. + * + * @details + * <b>Scaling and Overflow Behavior:</b> + * \par + * The function is implemented using an internal 64-bit accumulator. + * The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit. + * Thus, if the accumulator result overflows it wraps around rather than clip. + * In order to avoid overflows completely the input signal must be scaled down by 2*log2(numStages) bits. + * After all multiply-accumulates are performed, the 2.62 accumulator is saturated to 1.32 format and then truncated to 1.31 format. + */ + +void arm_iir_lattice_q31( + const arm_iir_lattice_instance_q31 * S, + q31_t * pSrc, + q31_t * pDst, + uint32_t blockSize) +{ + q31_t fcurr, fnext = 0, gcurr = 0, gnext; /* Temporary variables for lattice stages */ + q63_t acc; /* Accumlator */ + uint32_t blkCnt, tapCnt; /* Temporary variables for counts */ + q31_t *px1, *px2, *pk, *pv; /* Temporary pointers for state and coef */ + uint32_t numStages = S->numStages; /* number of stages */ + q31_t *pState; /* State pointer */ + q31_t *pStateCurnt; /* State current pointer */ + + blkCnt = blockSize; + + pState = &S->pState[0]; + + +#ifndef ARM_MATH_CM0_FAMILY + + /* Run the below code for Cortex-M4 and Cortex-M3 */ + + /* Sample processing */ + while(blkCnt > 0u) + { + /* Read Sample from input buffer */ + /* fN(n) = x(n) */ + fcurr = *pSrc++; + + /* Initialize state read pointer */ + px1 = pState; + /* Initialize state write pointer */ + px2 = pState; + /* Set accumulator to zero */ + acc = 0; + /* Initialize Ladder coeff pointer */ + pv = &S->pvCoeffs[0]; + /* Initialize Reflection coeff pointer */ + pk = &S->pkCoeffs[0]; + + + /* Process sample for first tap */ + gcurr = *px1++; + /* fN-1(n) = fN(n) - kN * gN-1(n-1) */ + fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31)); + /* gN(n) = kN * fN-1(n) + gN-1(n-1) */ + gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31)); + /* write gN-1(n-1) into state for next sample processing */ + *px2++ = gnext; + /* y(n) += gN(n) * vN */ + acc += ((q63_t) gnext * *pv++); + + /* Update f values for next coefficient processing */ + fcurr = fnext; + + /* Loop unrolling. Process 4 taps at a time. */ + tapCnt = (numStages - 1u) >> 2; + + while(tapCnt > 0u) + { + + /* Process sample for 2nd, 6th .. taps */ + /* Read gN-2(n-1) from state buffer */ + gcurr = *px1++; + /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */ + fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31)); + /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */ + gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31)); + /* y(n) += gN-1(n) * vN-1 */ + /* process for gN-5(n) * vN-5, gN-9(n) * vN-9 ... */ + acc += ((q63_t) gnext * *pv++); + /* write gN-1(n) into state for next sample processing */ + *px2++ = gnext; + + /* Process sample for 3nd, 7th ...taps */ + /* Read gN-3(n-1) from state buffer */ + gcurr = *px1++; + /* Process sample for 3rd, 7th .. taps */ + /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */ + fcurr = __QSUB(fnext, (q31_t) (((q63_t) gcurr * (*pk)) >> 31)); + /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */ + gnext = __QADD(gcurr, (q31_t) (((q63_t) fcurr * (*pk++)) >> 31)); + /* y(n) += gN-2(n) * vN-2 */ + /* process for gN-6(n) * vN-6, gN-10(n) * vN-10 ... */ + acc += ((q63_t) gnext * *pv++); + /* write gN-2(n) into state for next sample processing */ + *px2++ = gnext; + + + /* Process sample for 4th, 8th ...taps */ + /* Read gN-4(n-1) from state buffer */ + gcurr = *px1++; + /* Process sample for 4th, 8th .. taps */ + /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */ + fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31)); + /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */ + gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31)); + /* y(n) += gN-3(n) * vN-3 */ + /* process for gN-7(n) * vN-7, gN-11(n) * vN-11 ... */ + acc += ((q63_t) gnext * *pv++); + /* write gN-3(n) into state for next sample processing */ + *px2++ = gnext; + + + /* Process sample for 5th, 9th ...taps */ + /* Read gN-5(n-1) from state buffer */ + gcurr = *px1++; + /* Process sample for 5th, 9th .. taps */ + /* fN-5(n) = fN-4(n) - kN-4 * gN-1(n-1) */ + fcurr = __QSUB(fnext, (q31_t) (((q63_t) gcurr * (*pk)) >> 31)); + /* gN-4(n) = kN-4 * fN-5(n) + gN-5(n-1) */ + gnext = __QADD(gcurr, (q31_t) (((q63_t) fcurr * (*pk++)) >> 31)); + /* y(n) += gN-4(n) * vN-4 */ + /* process for gN-8(n) * vN-8, gN-12(n) * vN-12 ... */ + acc += ((q63_t) gnext * *pv++); + /* write gN-4(n) into state for next sample processing */ + *px2++ = gnext; + + tapCnt--; + + } + + fnext = fcurr; + + /* If the filter length is not a multiple of 4, compute the remaining filter taps */ + tapCnt = (numStages - 1u) % 0x4u; + + while(tapCnt > 0u) + { + gcurr = *px1++; + /* Process sample for last taps */ + fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31)); + gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31)); + /* Output samples for last taps */ + acc += ((q63_t) gnext * *pv++); + *px2++ = gnext; + fcurr = fnext; + + tapCnt--; + + } + + /* y(n) += g0(n) * v0 */ + acc += (q63_t) fnext *( + *pv++); + + *px2++ = fnext; + + /* write out into pDst */ + *pDst++ = (q31_t) (acc >> 31u); + + /* Advance the state pointer by 4 to process the next group of 4 samples */ + pState = pState + 1u; + blkCnt--; + + } + + /* Processing is complete. Now copy last S->numStages samples to start of the buffer + for the preperation of next frame process */ + + /* Points to the start of the state buffer */ + pStateCurnt = &S->pState[0]; + pState = &S->pState[blockSize]; + + tapCnt = numStages >> 2u; + + /* copy data */ + while(tapCnt > 0u) + { + *pStateCurnt++ = *pState++; + *pStateCurnt++ = *pState++; + *pStateCurnt++ = *pState++; + *pStateCurnt++ = *pState++; + + /* Decrement the loop counter */ + tapCnt--; + + } + + /* Calculate remaining number of copies */ + tapCnt = (numStages) % 0x4u; + + /* Copy the remaining q31_t data */ + while(tapCnt > 0u) + { + *pStateCurnt++ = *pState++; + + /* Decrement the loop counter */ + tapCnt--; + }; + +#else + + /* Run the below code for Cortex-M0 */ + /* Sample processing */ + while(blkCnt > 0u) + { + /* Read Sample from input buffer */ + /* fN(n) = x(n) */ + fcurr = *pSrc++; + + /* Initialize state read pointer */ + px1 = pState; + /* Initialize state write pointer */ + px2 = pState; + /* Set accumulator to zero */ + acc = 0; + /* Initialize Ladder coeff pointer */ + pv = &S->pvCoeffs[0]; + /* Initialize Reflection coeff pointer */ + pk = &S->pkCoeffs[0]; + + tapCnt = numStages; + + while(tapCnt > 0u) + { + gcurr = *px1++; + /* Process sample */ + /* fN-1(n) = fN(n) - kN * gN-1(n-1) */ + fnext = + clip_q63_to_q31(((q63_t) fcurr - + ((q31_t) (((q63_t) gcurr * (*pk)) >> 31)))); + /* gN(n) = kN * fN-1(n) + gN-1(n-1) */ + gnext = + clip_q63_to_q31(((q63_t) gcurr + + ((q31_t) (((q63_t) fnext * (*pk++)) >> 31)))); + /* Output samples */ + /* y(n) += gN(n) * vN */ + acc += ((q63_t) gnext * *pv++); + /* write gN-1(n-1) into state for next sample processing */ + *px2++ = gnext; + /* Update f values for next coefficient processing */ + fcurr = fnext; + + tapCnt--; + } + + /* y(n) += g0(n) * v0 */ + acc += (q63_t) fnext *( + *pv++); + + *px2++ = fnext; + + /* write out into pDst */ + *pDst++ = (q31_t) (acc >> 31u); + + /* Advance the state pointer by 1 to process the next group of samples */ + pState = pState + 1u; + blkCnt--; + + } + + /* Processing is complete. Now copy last S->numStages samples to start of the buffer + for the preperation of next frame process */ + + /* Points to the start of the state buffer */ + pStateCurnt = &S->pState[0]; + pState = &S->pState[blockSize]; + + tapCnt = numStages; + + /* Copy the remaining q31_t data */ + while(tapCnt > 0u) + { + *pStateCurnt++ = *pState++; + + /* Decrement the loop counter */ + tapCnt--; + } + +#endif /* #ifndef ARM_MATH_CM0_FAMILY */ + +} + + + + +/** + * @} end of IIR_Lattice group + */ |