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| Rev | Author | Line No. | Line |
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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_negate_q7.c |
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| 4 | * Description: Negates Q7 vectors |
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| 5 | * |
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| 6 | * $Date: 27. January 2017 |
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| 7 | * $Revision: V.1.5.1 |
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| 8 | * |
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| 9 | * Target Processor: Cortex-M cores |
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| 10 | * -------------------------------------------------------------------- */ |
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| 11 | /* |
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| 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
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| 13 | * |
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| 14 | * SPDX-License-Identifier: Apache-2.0 |
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| 15 | * |
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| 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
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| 17 | * not use this file except in compliance with the License. |
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| 18 | * You may obtain a copy of the License at |
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| 19 | * |
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| 20 | * www.apache.org/licenses/LICENSE-2.0 |
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| 21 | * |
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| 22 | * Unless required by applicable law or agreed to in writing, software |
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| 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
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| 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 25 | * See the License for the specific language governing permissions and |
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| 26 | * limitations under the License. |
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| 27 | */ |
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| 28 | |||
| 29 | #include "arm_math.h" |
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| 30 | |||
| 31 | /** |
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| 32 | * @ingroup groupMath |
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| 33 | */ |
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| 34 | |||
| 35 | /** |
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| 36 | * @addtogroup negate |
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| 37 | * @{ |
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| 38 | */ |
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| 39 | |||
| 40 | /** |
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| 41 | * @brief Negates the elements of a Q7 vector. |
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| 42 | * @param[in] *pSrc points to the input vector |
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| 43 | * @param[out] *pDst points to the output vector |
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| 44 | * @param[in] blockSize number of samples in the vector |
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| 45 | * @return none. |
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| 46 | * |
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| 47 | * <b>Scaling and Overflow Behavior:</b> |
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| 48 | * \par |
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| 49 | * The function uses saturating arithmetic. |
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| 50 | * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F. |
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| 51 | */ |
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| 52 | |||
| 53 | void arm_negate_q7( |
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| 54 | q7_t * pSrc, |
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| 55 | q7_t * pDst, |
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| 56 | uint32_t blockSize) |
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| 57 | { |
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| 58 | uint32_t blkCnt; /* loop counter */ |
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| 59 | q7_t in; |
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| 60 | |||
| 61 | #if defined (ARM_MATH_DSP) |
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| 62 | |||
| 63 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 64 | q31_t input; /* Input values1-4 */ |
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| 65 | q31_t zero = 0x00000000; |
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| 66 | |||
| 67 | |||
| 68 | /*loop Unrolling */ |
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| 69 | blkCnt = blockSize >> 2U; |
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| 70 | |||
| 71 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 72 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 73 | while (blkCnt > 0U) |
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| 74 | { |
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| 75 | /* C = -A */ |
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| 76 | /* Read four inputs */ |
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| 77 | input = *__SIMD32(pSrc)++; |
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| 78 | |||
| 79 | /* Store the Negated results in the destination buffer in a single cycle by packing the results */ |
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| 80 | *__SIMD32(pDst)++ = __QSUB8(zero, input); |
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| 81 | |||
| 82 | /* Decrement the loop counter */ |
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| 83 | blkCnt--; |
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| 84 | } |
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| 85 | |||
| 86 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 87 | ** No loop unrolling is used. */ |
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| 88 | blkCnt = blockSize % 0x4U; |
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| 89 | |||
| 90 | #else |
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| 91 | |||
| 92 | /* Run the below code for Cortex-M0 */ |
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| 93 | |||
| 94 | /* Initialize blkCnt with number of samples */ |
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| 95 | blkCnt = blockSize; |
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| 96 | |||
| 97 | #endif /* #if defined (ARM_MATH_DSP) */ |
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| 98 | |||
| 99 | while (blkCnt > 0U) |
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| 100 | { |
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| 101 | /* C = -A */ |
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| 102 | /* Negate and then store the results in the destination buffer. */ \ |
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| 103 | in = *pSrc++; |
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| 104 | *pDst++ = (in == (q7_t) 0x80) ? 0x7f : -in; |
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| 105 | |||
| 106 | /* Decrement the loop counter */ |
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| 107 | blkCnt--; |
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| 108 | } |
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| 109 | } |
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| 110 | |||
| 111 | /** |
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| 112 | * @} end of negate group |
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| 113 | */ |