CMSIS DSP Library from CMSIS 2.0. See http://www.onarm.com/cmsis/ for full details
Dependents: K22F_DSP_Matrix_least_square BNO055-ELEC3810 1BNO055 ECE4180Project--Slave2 ... more
Diff: src/Cortex-M4-M3/FilteringFunctions/arm_fir_interpolate_q15.c
- Revision:
- 0:1014af42efd9
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/Cortex-M4-M3/FilteringFunctions/arm_fir_interpolate_q15.c Thu Mar 10 15:07:50 2011 +0000 @@ -0,0 +1,232 @@ +/*----------------------------------------------------------------------------- +* Copyright (C) 2010 ARM Limited. All rights reserved. +* +* $Date: 29. November 2010 +* $Revision: V1.0.3 +* +* Project: CMSIS DSP Library +* Title: arm_fir_interpolate_q15.c +* +* Description: Q15 FIR interpolation. +* +* Target Processor: Cortex-M4/Cortex-M3 +* +* Version 1.0.3 2010/11/29 +* Re-organized the CMSIS folders and updated documentation. +* +* Version 1.0.2 2010/11/11 +* Documentation updated. +* +* Version 1.0.1 2010/10/05 +* Production release and review comments incorporated. +* +* Version 1.0.0 2010/09/20 +* Production release and review comments incorporated +* +* Version 0.0.7 2010/06/10 +* Misra-C changes done +* ---------------------------------------------------------------------------*/ + +#include "arm_math.h" + +/** + * @ingroup groupFilters + */ + +/** + * @addtogroup FIR_Interpolate + * @{ + */ + +/** + * @brief Processing function for the Q15 FIR interpolator. + * @param[in] *S points to an instance of the Q15 FIR interpolator 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 input samples to process per call. + * @return none. + * + * <b>Scaling and Overflow Behavior:</b> + * \par + * The function is implemented using a 64-bit internal accumulator. + * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result. + * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format. + * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved. + * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits. + * Lastly, the accumulator is saturated to yield a result in 1.15 format. + */ + +void arm_fir_interpolate_q15( + const arm_fir_interpolate_instance_q15 * S, + q15_t * pSrc, + q15_t * pDst, + uint32_t blockSize) +{ + q15_t *pState = S->pState; /* State pointer */ + q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ + q15_t *pStateCurnt; /* Points to the current sample of the state */ + q15_t *ptr1, *ptr2; /* Temporary pointers for state and coefficient buffers */ + q63_t sum0; /* Accumulators */ + q15_t x0, c0, c1; /* Temporary variables to hold state and coefficient values */ + q31_t c, x; + uint32_t i, blkCnt, j, tapCnt; /* Loop counters */ + uint16_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */ + + + /* S->pState buffer contains previous frame (phaseLen - 1) samples */ + /* pStateCurnt points to the location where the new input data should be written */ + pStateCurnt = S->pState + (phaseLen - 1u); + + /* Total number of intput samples */ + blkCnt = blockSize; + + /* Loop over the blockSize. */ + while(blkCnt > 0u) + { + /* Copy new input sample into the state buffer */ + *pStateCurnt++ = *pSrc++; + + /* Address modifier index of coefficient buffer */ + j = 1u; + + /* Loop over the Interpolation factor. */ + i = S->L; + while(i > 0u) + { + /* Set accumulator to zero */ + sum0 = 0; + + /* Initialize state pointer */ + ptr1 = pState; + + /* Initialize coefficient pointer */ + ptr2 = pCoeffs + (S->L - j); + + /* Loop over the polyPhase length. Unroll by a factor of 4. + ** Repeat until we've computed numTaps-(4*S->L) coefficients. */ + tapCnt = (uint32_t) phaseLen >> 2u; + while(tapCnt > 0u) + { + /* Read the coefficient */ + c0 = *(ptr2); + + /* Upsampling is done by stuffing L-1 zeros between each sample. + * So instead of multiplying zeros with coefficients, + * Increment the coefficient pointer by interpolation factor times. */ + ptr2 += S->L; + + /* Read the coefficient */ + c1 = *(ptr2); + + /* Increment the coefficient pointer by interpolation factor times. */ + ptr2 += S->L; + + /* Pack the coefficients */ + c = __PKHBT(c0, c1, 16); + + /* Read twp consecutive input samples */ + x = *__SIMD32(ptr1)++; + + /* Perform the multiply-accumulate */ + sum0 = __SMLALD(x, c, sum0); + + /* Read the coefficient */ + c0 = *(ptr2); + + /* Upsampling is done by stuffing L-1 zeros between each sample. + * So insted of multiplying zeros with coefficients, + * Increment the coefficient pointer by interpolation factor times. */ + ptr2 += S->L; + + /* Read the coefficient */ + c1 = *(ptr2); + + /* Increment the coefficient pointer by interpolation factor times. */ + ptr2 += S->L; + + /* Pack the coefficients */ + c = __PKHBT(c0, c1, 16); + + /* Read twp consecutive input samples */ + x = *__SIMD32(ptr1)++; + + /* Perform the multiply-accumulate */ + sum0 = __SMLALD(x, c, sum0); + + /* Decrement the loop counter */ + tapCnt--; + } + + /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */ + tapCnt = (uint32_t) phaseLen & 0x3u; + + while(tapCnt > 0u) + { + /* Read the coefficient */ + c0 = *(ptr2); + + /* Increment the coefficient pointer by interpolation factor times. */ + ptr2 += S->L; + + /* Read the input sample */ + x0 = *(ptr1++); + + /* Perform the multiply-accumulate */ + sum0 = __SMLALD(x0, c0, sum0); + + /* Decrement the loop counter */ + tapCnt--; + } + + /* The result is in the accumulator, store in the destination buffer. */ + *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); + + /* Increment the address modifier index of coefficient buffer */ + j++; + + /* Decrement the loop counter */ + i--; + } + + /* Advance the state pointer by 1 + * to process the next group of interpolation factor number samples */ + pState = pState + 1; + + /* Decrement the loop counter */ + blkCnt--; + } + + /* Processing is complete. + ** Now copy the last phaseLen - 1 samples to the satrt of the state buffer. + ** This prepares the state buffer for the next function call. */ + + /* Points to the start of the state buffer */ + pStateCurnt = S->pState; + + i = ((uint32_t) phaseLen - 1u) >> 2u; + + /* copy data */ + while(i > 0u) + { + *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; + *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; + + /* Decrement the loop counter */ + i--; + } + + i = ((uint32_t) phaseLen - 1u) % 0x04u; + + while(i > 0u) + { + *pStateCurnt++ = *pState++; + + /* Decrement the loop counter */ + i--; + } + +} + + /** + * @} end of FIR_Interpolate group + */