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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
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| 3 | * |
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| 4 | * $Date: 19. March 2015 |
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| 5 | * $Revision: V.1.4.5 |
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| 6 | * |
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| 7 | * Project: CMSIS DSP Library |
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| 8 | * Title: arm_negate_q15.c |
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| 9 | * |
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| 10 | * Description: Negates Q15 vectors. |
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| 11 | * |
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| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
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| 13 | * |
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| 14 | * Redistribution and use in source and binary forms, with or without |
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| 15 | * modification, are permitted provided that the following conditions |
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| 16 | * are met: |
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| 17 | * - Redistributions of source code must retain the above copyright |
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| 18 | * notice, this list of conditions and the following disclaimer. |
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| 19 | * - Redistributions in binary form must reproduce the above copyright |
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| 20 | * notice, this list of conditions and the following disclaimer in |
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| 21 | * the documentation and/or other materials provided with the |
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| 22 | * distribution. |
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| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
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| 24 | * may be used to endorse or promote products derived from this |
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| 25 | * software without specific prior written permission. |
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| 26 | * |
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| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 38 | * POSSIBILITY OF SUCH DAMAGE. |
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| 39 | * -------------------------------------------------------------------- */ |
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| 40 | #include "arm_math.h" |
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| 41 | |||
| 42 | /** |
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| 43 | * @ingroup groupMath |
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| 44 | */ |
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| 45 | |||
| 46 | /** |
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| 47 | * @addtogroup negate |
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| 48 | * @{ |
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| 49 | */ |
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| 50 | |||
| 51 | /** |
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| 52 | * @brief Negates the elements of a Q15 vector. |
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| 53 | * @param[in] *pSrc points to the input vector |
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| 54 | * @param[out] *pDst points to the output vector |
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| 55 | * @param[in] blockSize number of samples in the vector |
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| 56 | * @return none. |
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| 57 | * |
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| 58 | * \par Conditions for optimum performance |
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| 59 | * Input and output buffers should be aligned by 32-bit |
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| 60 | * |
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| 61 | * |
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| 62 | * <b>Scaling and Overflow Behavior:</b> |
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| 63 | * \par |
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| 64 | * The function uses saturating arithmetic. |
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| 65 | * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF. |
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| 66 | */ |
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| 67 | |||
| 68 | void arm_negate_q15( |
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| 69 | q15_t * pSrc, |
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| 70 | q15_t * pDst, |
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| 71 | uint32_t blockSize) |
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| 72 | { |
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| 73 | uint32_t blkCnt; /* loop counter */ |
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| 74 | q15_t in; |
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| 75 | |||
| 76 | #ifndef ARM_MATH_CM0_FAMILY |
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| 77 | |||
| 78 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 79 | |||
| 80 | q31_t in1, in2; /* Temporary variables */ |
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| 81 | |||
| 82 | |||
| 83 | /*loop Unrolling */ |
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| 84 | blkCnt = blockSize >> 2u; |
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| 85 | |||
| 86 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 87 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 88 | while(blkCnt > 0u) |
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| 89 | { |
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| 90 | /* C = -A */ |
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| 91 | /* Read two inputs at a time */ |
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| 92 | in1 = _SIMD32_OFFSET(pSrc); |
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| 93 | in2 = _SIMD32_OFFSET(pSrc + 2); |
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| 94 | |||
| 95 | /* negate two samples at a time */ |
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| 96 | in1 = __QSUB16(0, in1); |
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| 97 | |||
| 98 | /* negate two samples at a time */ |
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| 99 | in2 = __QSUB16(0, in2); |
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| 100 | |||
| 101 | /* store the result to destination 2 samples at a time */ |
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| 102 | _SIMD32_OFFSET(pDst) = in1; |
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| 103 | /* store the result to destination 2 samples at a time */ |
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| 104 | _SIMD32_OFFSET(pDst + 2) = in2; |
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| 105 | |||
| 106 | |||
| 107 | /* update pointers to process next samples */ |
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| 108 | pSrc += 4u; |
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| 109 | pDst += 4u; |
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| 110 | |||
| 111 | /* Decrement the loop counter */ |
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| 112 | blkCnt--; |
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| 113 | } |
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| 114 | |||
| 115 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 116 | ** No loop unrolling is used. */ |
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| 117 | blkCnt = blockSize % 0x4u; |
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| 118 | |||
| 119 | #else |
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| 120 | |||
| 121 | /* Run the below code for Cortex-M0 */ |
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| 122 | |||
| 123 | /* Initialize blkCnt with number of samples */ |
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| 124 | blkCnt = blockSize; |
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| 125 | |||
| 126 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
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| 127 | |||
| 128 | while(blkCnt > 0u) |
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| 129 | { |
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| 130 | /* C = -A */ |
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| 131 | /* Negate and then store the result in the destination buffer. */ |
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| 132 | in = *pSrc++; |
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| 133 | *pDst++ = (in == (q15_t) 0x8000) ? 0x7fff : -in; |
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| 134 | |||
| 135 | /* Decrement the loop counter */ |
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| 136 | blkCnt--; |
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| 137 | } |
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| 138 | } |
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| 139 | |||
| 140 | /** |
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| 141 | * @} end of negate group |
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| 142 | */ |