| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_negate_q7.c |
| * Description: Negates Q7 vectors |
| * |
| * $Date: 27. January 2017 |
| * $Revision: V.1.5.1 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2017 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 negate |
| * @{ |
| */ |
| |
| /** |
| * @brief Negates the elements of a Q7 vector. |
| * @param[in] *pSrc points to the input vector |
| * @param[out] *pDst points to the output vector |
| * @param[in] blockSize number of samples in the vector |
| * @return none. |
| * |
| * <b>Scaling and Overflow Behavior:</b> |
| * \par |
| * The function uses saturating arithmetic. |
| * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F. |
| */ |
| |
| void arm_negate_q7( |
| q7_t * pSrc, |
| q7_t * pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* loop counter */ |
| q7_t in; |
| |
| #if defined (ARM_MATH_DSP) |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| q31_t input; /* Input values1-4 */ |
| q31_t zero = 0x00000000; |
| |
| |
| /*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 */ |
| /* Read four inputs */ |
| input = *__SIMD32(pSrc)++; |
| |
| /* Store the Negated results in the destination buffer in a single cycle by packing the results */ |
| *__SIMD32(pDst)++ = __QSUB8(zero, input); |
| |
| /* 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; |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = blockSize; |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| |
| while (blkCnt > 0U) |
| { |
| /* C = -A */ |
| /* Negate and then store the results in the destination buffer. */ \ |
| in = *pSrc++; |
| *pDst++ = (in == (q7_t) 0x80) ? 0x7f : -in; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| } |
| |
| /** |
| * @} end of negate group |
| */ |