/* ---------------------------------------------------------------------- * Project: CMSIS DSP Library * Title: arm_mean_f32.c * Description: Mean value of a floating-point vector * * $Date: 18. March 2019 * $Revision: V1.6.0 * * Target Processor: Cortex-M cores * -------------------------------------------------------------------- */ /* * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. * * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the License); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an AS IS BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "arm_math.h" /** @ingroup groupStats */ /** @defgroup mean Mean Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector. The underlying algorithm is used:
      Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;
  
There are separate functions for floating-point, Q31, Q15, and Q7 data types. */ /** @addtogroup mean @{ */ /** @brief Mean value of a floating-point vector. @param[in] pSrc points to the input vector. @param[in] blockSize number of samples in input vector. @param[out] pResult mean value returned here. @return none */ #if defined(ARM_MATH_NEON_EXPERIMENTAL) void arm_mean_f32( const float32_t * pSrc, uint32_t blockSize, float32_t * pResult) { float32_t sum = 0.0f; /* Temporary result storage */ float32x4_t sumV = vdupq_n_f32(0.0f); /* Temporary result storage */ float32x2_t sumV2; uint32_t blkCnt; /* Loop counter */ float32_t in1, in2, in3, in4; float32x4_t inV; blkCnt = blockSize >> 2U; /* Compute 4 outputs at a time. ** a second loop below computes the remaining 1 to 3 samples. */ while (blkCnt > 0U) { /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ inV = vld1q_f32(pSrc); sumV = vaddq_f32(sumV, inV); pSrc += 4; /* Decrement the loop counter */ blkCnt--; } sumV2 = vpadd_f32(vget_low_f32(sumV),vget_high_f32(sumV)); sum = sumV2[0] + sumV2[1]; /* If the blockSize is not a multiple of 4, compute any remaining output samples here. ** No loop unrolling is used. */ blkCnt = blockSize & 3; while (blkCnt > 0U) { /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ sum += *pSrc++; /* Decrement the loop counter */ blkCnt--; } /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */ /* Store the result to the destination */ *pResult = sum / (float32_t) blockSize; } #else void arm_mean_f32( const float32_t * pSrc, uint32_t blockSize, float32_t * pResult) { uint32_t blkCnt; /* Loop counter */ float32_t sum = 0.0f; /* Temporary result storage */ #if defined (ARM_MATH_LOOPUNROLL) /* Loop unrolling: Compute 4 outputs at a time */ blkCnt = blockSize >> 2U; while (blkCnt > 0U) { /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ sum += *pSrc++; sum += *pSrc++; sum += *pSrc++; sum += *pSrc++; /* Decrement the loop counter */ blkCnt--; } /* Loop unrolling: Compute remaining outputs */ blkCnt = blockSize % 0x4U; #else /* Initialize blkCnt with number of samples */ blkCnt = blockSize; #endif /* #if defined (ARM_MATH_LOOPUNROLL) */ while (blkCnt > 0U) { /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ sum += *pSrc++; /* Decrement loop counter */ blkCnt--; } /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */ /* Store result to destination */ *pResult = (sum / blockSize); } #endif /* #if defined(ARM_MATH_NEON) */ /** @} end of mean group */