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| 56 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_abs_q7.c |
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| 4 | * Description: Q7 vector absolute value |
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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 BasicAbs |
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| 37 | * @{ |
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| 38 | */ |
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| 39 | |||
| 40 | /** |
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| 41 | * @brief Q7 vector absolute value. |
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| 42 | * @param[in] *pSrc points to the input buffer |
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| 43 | * @param[out] *pDst points to the output buffer |
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| 44 | * @param[in] blockSize number of samples in each vector |
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| 45 | * @return none. |
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| 46 | * |
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| 47 | * \par Conditions for optimum performance |
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| 48 | * Input and output buffers should be aligned by 32-bit |
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| 49 | * |
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| 50 | * |
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| 51 | * <b>Scaling and Overflow Behavior:</b> |
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| 52 | * \par |
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| 53 | * The function uses saturating arithmetic. |
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| 54 | * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F. |
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| 55 | */ |
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| 56 | |||
| 57 | void arm_abs_q7( |
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| 58 | q7_t * pSrc, |
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| 59 | q7_t * pDst, |
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| 60 | uint32_t blockSize) |
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| 61 | { |
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| 62 | uint32_t blkCnt; /* loop counter */ |
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| 63 | q7_t in; /* Input value1 */ |
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| 64 | |||
| 65 | #if defined (ARM_MATH_DSP) |
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| 66 | |||
| 67 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 68 | q31_t in1, in2, in3, in4; /* temporary input variables */ |
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| 69 | q31_t out1, out2, out3, out4; /* temporary output variables */ |
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| 70 | |||
| 71 | /*loop Unrolling */ |
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| 72 | blkCnt = blockSize >> 2U; |
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| 73 | |||
| 74 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 75 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 76 | while (blkCnt > 0U) |
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| 77 | { |
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| 78 | /* C = |A| */ |
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| 79 | /* Read inputs */ |
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| 80 | in1 = (q31_t) * pSrc; |
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| 81 | in2 = (q31_t) * (pSrc + 1); |
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| 82 | in3 = (q31_t) * (pSrc + 2); |
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| 83 | |||
| 84 | /* find absolute value */ |
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| 85 | out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1); |
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| 86 | |||
| 87 | /* read input */ |
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| 88 | in4 = (q31_t) * (pSrc + 3); |
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| 89 | |||
| 90 | /* find absolute value */ |
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| 91 | out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2); |
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| 92 | |||
| 93 | /* store result to destination */ |
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| 94 | *pDst = (q7_t) out1; |
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| 95 | |||
| 96 | /* find absolute value */ |
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| 97 | out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3); |
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| 98 | |||
| 99 | /* find absolute value */ |
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| 100 | out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4); |
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| 101 | |||
| 102 | /* store result to destination */ |
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| 103 | *(pDst + 1) = (q7_t) out2; |
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| 104 | |||
| 105 | /* store result to destination */ |
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| 106 | *(pDst + 2) = (q7_t) out3; |
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| 107 | |||
| 108 | /* store result to destination */ |
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| 109 | *(pDst + 3) = (q7_t) out4; |
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| 110 | |||
| 111 | /* update pointers to process next samples */ |
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| 112 | pSrc += 4U; |
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| 113 | pDst += 4U; |
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| 114 | |||
| 115 | /* Decrement the loop counter */ |
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| 116 | blkCnt--; |
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| 117 | } |
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| 118 | |||
| 119 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 120 | ** No loop unrolling is used. */ |
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| 121 | blkCnt = blockSize % 0x4U; |
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| 122 | #else |
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| 123 | |||
| 124 | /* Run the below code for Cortex-M0 */ |
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| 125 | blkCnt = blockSize; |
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| 126 | |||
| 127 | #endif /* #define ARM_MATH_CM0_FAMILY */ |
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| 128 | |||
| 129 | while (blkCnt > 0U) |
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| 130 | { |
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| 131 | /* C = |A| */ |
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| 132 | /* Read the input */ |
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| 133 | in = *pSrc++; |
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| 134 | |||
| 135 | /* Store the Absolute result in the destination buffer */ |
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| 136 | *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in); |
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| 137 | |||
| 138 | /* Decrement the loop counter */ |
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| 139 | blkCnt--; |
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| 140 | } |
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| 141 | } |
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| 142 | |||
| 143 | /** |
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| 144 | * @} end of BasicAbs group |
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| 145 | */ |