/*----------------------------------------------------------------------------- * Copyright (C) 2010-2013 ARM Limited. All rights reserved. * * $Date: 17. January 2013 * $Revision: V1.4.1 * * Project: CMSIS DSP Library * Title: arm_fir_interpolate_q15.c * * Description: Q15 FIR interpolation. * * 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 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. * * Scaling and Overflow Behavior: * \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. */ #ifndef ARM_MATH_CM0_FAMILY /* Run the below code for Cortex-M4 and Cortex-M3 */ 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; /* Temporary variables to hold state and coefficient values */ uint32_t i, blkCnt, j, tapCnt; /* Loop counters */ uint16_t phaseLen = S->phaseLength; /* Length of each polyphase filter component */ uint32_t blkCntN2; q63_t acc0, acc1; q15_t x1; /* 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 + ((q31_t) phaseLen - 1); /* Initialise blkCnt */ blkCnt = blockSize / 2; blkCntN2 = blockSize - (2 * blkCnt); /* Samples loop unrolled by 2 */ while(blkCnt > 0u) { /* Copy new input sample into the state buffer */ *pStateCurnt++ = *pSrc++; *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 */ acc0 = 0; acc1 = 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 = phaseLen >> 2u; x0 = *(ptr1++); while(tapCnt > 0u) { /* Read the input sample */ x1 = *(ptr1++); /* Read the coefficient */ c0 = *(ptr2); /* Perform the multiply-accumulate */ acc0 += (q63_t) x0 *c0; acc1 += (q63_t) x1 *c0; /* Read the coefficient */ c0 = *(ptr2 + S->L); /* Read the input sample */ x0 = *(ptr1++); /* Perform the multiply-accumulate */ acc0 += (q63_t) x1 *c0; acc1 += (q63_t) x0 *c0; /* Read the coefficient */ c0 = *(ptr2 + S->L * 2); /* Read the input sample */ x1 = *(ptr1++); /* Perform the multiply-accumulate */ acc0 += (q63_t) x0 *c0; acc1 += (q63_t) x1 *c0; /* Read the coefficient */ c0 = *(ptr2 + S->L * 3); /* Read the input sample */ x0 = *(ptr1++); /* Perform the multiply-accumulate */ acc0 += (q63_t) x1 *c0; acc1 += (q63_t) x0 *c0; /* 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 += 4 * S->L; /* Decrement the loop counter */ tapCnt--; } /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */ tapCnt = phaseLen % 0x4u; while(tapCnt > 0u) { /* Read the input sample */ x1 = *(ptr1++); /* Read the coefficient */ c0 = *(ptr2); /* Perform the multiply-accumulate */ acc0 += (q63_t) x0 *c0; acc1 += (q63_t) x1 *c0; /* Increment the coefficient pointer by interpolation factor times. */ ptr2 += S->L; /* update states for next sample processing */ x0 = x1; /* Decrement the loop counter */ tapCnt--; } /* The result is in the accumulator, store in the destination buffer. */ *pDst = (q15_t) (__SSAT((acc0 >> 15), 16)); *(pDst + S->L) = (q15_t) (__SSAT((acc1 >> 15), 16)); pDst++; /* 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 + 2; pDst += S->L; /* Decrement the loop counter */ blkCnt--; } /* If the blockSize is not a multiple of 2, compute any remaining output samples here. ** No loop unrolling is used. */ blkCnt = blkCntN2; /* 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 = phaseLen >> 2; 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 input sample */ x0 = *(ptr1++); /* Perform the multiply-accumulate */ sum0 += (q63_t) x0 *c0; /* 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 += (q63_t) x0 *c0; /* 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 += (q63_t) x0 *c0; /* 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 += (q63_t) x0 *c0; /* Decrement the loop counter */ tapCnt--; } /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */ tapCnt = 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 += (q63_t) x0 *c0; /* Decrement the loop counter */ tapCnt--; } /* The result is in the accumulator, store in the destination buffer. */ *pDst++ = (q15_t) (__SSAT((sum0 >> 15), 16)); 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) { #ifndef UNALIGNED_SUPPORT_DISABLE *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++; #else *pStateCurnt++ = *pState++; *pStateCurnt++ = *pState++; *pStateCurnt++ = *pState++; *pStateCurnt++ = *pState++; #endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */ /* Decrement the loop counter */ i--; } i = ((uint32_t) phaseLen - 1u) % 0x04u; while(i > 0u) { *pStateCurnt++ = *pState++; /* Decrement the loop counter */ i--; } } #else /* Run the below code for Cortex-M0 */ 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 sum; /* Accumulator */ q15_t x0, c0; /* Temporary variables to hold state and coefficient values */ uint32_t i, blkCnt, 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++; /* Loop over the Interpolation factor. */ i = S->L; while(i > 0u) { /* Set accumulator to zero */ sum = 0; /* Initialize state pointer */ ptr1 = pState; /* Initialize coefficient pointer */ ptr2 = pCoeffs + (i - 1u); /* Loop over the polyPhase length */ tapCnt = (uint32_t) phaseLen; 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 */ sum += ((q31_t) x0 * c0); /* Decrement the loop counter */ tapCnt--; } /* Store the result after converting to 1.15 format in the destination buffer */ *pDst++ = (q15_t) (__SSAT((sum >> 15), 16)); /* 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 start 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; while(i > 0u) { *pStateCurnt++ = *pState++; /* Decrement the loop counter */ i--; } } #endif /* #ifndef ARM_MATH_CM0_FAMILY */ /** * @} end of FIR_Interpolate group */