| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_max_q31.c |
| * Description: Maximum value of a Q31 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 |
| */ |
| |
| /** |
| @addtogroup Max |
| @{ |
| */ |
| |
| /** |
| @brief Maximum value of a Q31 vector. |
| @param[in] pSrc points to the input vector |
| @param[in] blockSize number of samples in input vector |
| @param[out] pResult maximum value returned here |
| @param[out] pIndex index of maximum value returned here |
| @return none |
| */ |
| |
| void arm_max_q31( |
| const q31_t * pSrc, |
| uint32_t blockSize, |
| q31_t * pResult, |
| uint32_t * pIndex) |
| { |
| q31_t maxVal, out; /* Temporary variables to store the output value. */ |
| uint32_t blkCnt, outIndex; /* Loop counter */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| uint32_t index; /* index of maximum value */ |
| #endif |
| |
| /* Initialise index value to zero. */ |
| outIndex = 0U; |
| /* Load first input value that act as reference value for comparision */ |
| out = *pSrc++; |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| /* Initialise index of maximum value. */ |
| index = 0U; |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = (blockSize - 1U) >> 2U; |
| |
| while (blkCnt > 0U) |
| { |
| /* Initialize maxVal to next consecutive values one by one */ |
| maxVal = *pSrc++; |
| |
| /* compare for the maximum value */ |
| if (out < maxVal) |
| { |
| /* Update the maximum value and it's index */ |
| out = maxVal; |
| outIndex = index + 1U; |
| } |
| |
| maxVal = *pSrc++; |
| if (out < maxVal) |
| { |
| out = maxVal; |
| outIndex = index + 2U; |
| } |
| |
| maxVal = *pSrc++; |
| if (out < maxVal) |
| { |
| out = maxVal; |
| outIndex = index + 3U; |
| } |
| |
| maxVal = *pSrc++; |
| if (out < maxVal) |
| { |
| out = maxVal; |
| outIndex = index + 4U; |
| } |
| |
| index += 4U; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| /* Loop unrolling: Compute remaining outputs */ |
| blkCnt = (blockSize - 1U) % 4U; |
| |
| #else |
| |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = (blockSize - 1U); |
| |
| #endif /* #if defined (ARM_MATH_LOOPUNROLL) */ |
| |
| while (blkCnt > 0U) |
| { |
| /* Initialize maxVal to the next consecutive values one by one */ |
| maxVal = *pSrc++; |
| |
| /* compare for the maximum value */ |
| if (out < maxVal) |
| { |
| /* Update the maximum value and it's index */ |
| out = maxVal; |
| outIndex = blockSize - blkCnt; |
| } |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| /* Store the maximum value and it's index into destination pointers */ |
| *pResult = out; |
| *pIndex = outIndex; |
| } |
| |
| /** |
| @} end of Max group |
| */ |