/* ---------------------------------------------------------------------- * Copyright (C) 2010 ARM Limited. All rights reserved. * * $Date: 15. July 2011 * $Revision: V1.0.10 * * Project: CMSIS DSP Library * Title: arm_power_q15.c * * Description: Sum of the squares of the elements of a Q15 vector. * * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 * * Version 1.0.10 2011/7/15 * Big Endian support added and Merged M0 and M3/M4 Source code. * * 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. * -------------------------------------------------------------------- */ #include "arm_math.h" /** * @ingroup groupStats */ /** * @addtogroup power * @{ */ /** * @brief Sum of the squares of the elements of a Q15 vector. * @param[in] *pSrc points to the input vector * @param[in] blockSize length of the input vector * @param[out] *pResult sum of the squares value returned here * @return none. * * @details * Scaling and Overflow Behavior: * * \par * The function is implemented using a 64-bit internal accumulator. * The input is represented in 1.15 format. * Intermediate multiplication yields a 2.30 format, and this * result is added without saturation to a 64-bit accumulator in 34.30 format. * With 33 guard bits in the accumulator, there is no risk of overflow, and the * full precision of the intermediate multiplication is preserved. * Finally, the return result is in 34.30 format. * */ void arm_power_q15( q15_t * pSrc, uint32_t blockSize, q63_t * pResult) { q63_t sum = 0; /* Temporary result storage */ #ifndef ARM_MATH_CM0 /* Run the below code for Cortex-M4 and Cortex-M3 */ q31_t in32; /* Temporary variable to store input value */ q15_t in16; /* Temporary variable to store input value */ uint32_t blkCnt; /* loop counter */ /* loop Unrolling */ blkCnt = 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(blkCnt > 0u) { /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ /* Compute Power and then store the result in a temporary variable, sum. */ in32 = *__SIMD32(pSrc)++; sum = __SMLALD(in32, in32, sum); in32 = *__SIMD32(pSrc)++; sum = __SMLALD(in32, in32, sum); /* Decrement the loop counter */ blkCnt--; } /* If the blockSize is not a multiple of 4, compute any remaining output samples here. ** No loop unrolling is used. */ blkCnt = blockSize % 0x4u; while(blkCnt > 0u) { /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ /* Compute Power and then store the result in a temporary variable, sum. */ in16 = *pSrc++; sum = __SMLALD(in16, in16, sum); /* Decrement the loop counter */ blkCnt--; } #else /* Run the below code for Cortex-M0 */ q15_t in; /* Temporary variable to store input value */ uint32_t blkCnt; /* loop counter */ /* Loop over blockSize number of values */ blkCnt = blockSize; while(blkCnt > 0u) { /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ /* Compute Power and then store the result in a temporary variable, sum. */ in = *pSrc++; sum += ((q31_t) in * in); /* Decrement the loop counter */ blkCnt--; } #endif /* #ifndef ARM_MATH_CM0 */ /* Store the results in 34.30 format */ *pResult = sum; } /** * @} end of power group */