| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_negate_q15.c |
| * Description: Negates Q15 vectors |
| * |
| * $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 groupMath |
| */ |
| |
| /** |
| @addtogroup BasicNegate |
| @{ |
| */ |
| |
| /** |
| @brief Negates the elements of a Q15 vector. |
| @param[in] pSrc points to the input vector. |
| @param[out] pDst points to the output vector. |
| @param[in] blockSize number of samples in each vector. |
| @return none |
| |
| @par Conditions for optimum performance |
| Input and output buffers should be aligned by 32-bit |
| @par Scaling and Overflow Behavior |
| The function uses saturating arithmetic. |
| The Q15 value -1 (0x8000) is saturated to the maximum allowable positive value 0x7FFF. |
| */ |
| |
| void arm_negate_q15( |
| const q15_t * pSrc, |
| q15_t * pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| q15_t in; /* Temporary input variable */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| #if defined (ARM_MATH_DSP) |
| q31_t in1; /* Temporary input variables */ |
| #endif |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = -A */ |
| |
| #if defined (ARM_MATH_DSP) |
| /* Negate and store result in destination buffer (2 samples at a time). */ |
| in1 = read_q15x2_ia ((q15_t **) &pSrc); |
| write_q15x2_ia (&pDst, __QSUB16(0, in1)); |
| |
| in1 = read_q15x2_ia ((q15_t **) &pSrc); |
| write_q15x2_ia (&pDst, __QSUB16(0, in1)); |
| #else |
| in = *pSrc++; |
| *pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in; |
| |
| in = *pSrc++; |
| *pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in; |
| |
| in = *pSrc++; |
| *pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in; |
| |
| in = *pSrc++; |
| *pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in; |
| #endif |
| |
| /* Decrement 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 */ |
| |
| /* Negate and store result in destination buffer. */ |
| in = *pSrc++; |
| *pDst++ = (in == (q15_t) 0x8000) ? (q15_t) 0x7fff : -in; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| } |
| |
| /** |
| @} end of BasicNegate group |
| */ |