1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010 ARM Limited. All rights reserved.
7 * Project: CMSIS DSP Library
8 * Title: arm_negate_q15.c
10 * Description: Negates Q15 vectors.
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Version 1.0.10 2011/7/15
15 * Big Endian support added and Merged M0 and M3/M4 Source code.
17 * Version 1.0.3 2010/11/29
18 * Re-organized the CMSIS folders and updated documentation.
20 * Version 1.0.2 2010/11/11
21 * Documentation updated.
23 * Version 1.0.1 2010/10/05
24 * Production release and review comments incorporated.
26 * Version 1.0.0 2010/09/20
27 * Production release and review comments incorporated.
29 * Version 0.0.7 2010/06/10
30 * Misra-C changes done
31 * -------------------------------------------------------------------- */
45 * @brief Negates the elements of a Q15 vector.
46 * @param[in] *pSrc points to the input vector
47 * @param[out] *pDst points to the output vector
48 * @param[in] blockSize number of samples in the vector
51 * <b>Scaling and Overflow Behavior:</b>
53 * The function uses saturating arithmetic.
54 * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.
62 uint32_t blkCnt; /* loop counter */
67 /* Run the below code for Cortex-M4 and Cortex-M3 */
69 q15_t in1, in2; /* Temporary variables */
73 blkCnt = blockSize >> 2u;
75 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
76 ** a second loop below computes the remaining 1 to 3 samples. */
83 /* Negate and then store the results in the destination buffer by packing. */
85 #ifndef ARM_MATH_BIG_ENDIAN
87 *__SIMD32(pDst)++ = __PKHBT(__SSAT(-in1, 16), __SSAT(-in2, 16), 16);
91 *__SIMD32(pDst)++ = __PKHBT(__SSAT(-in2, 16), __SSAT(-in1, 16), 16);
93 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
98 #ifndef ARM_MATH_BIG_ENDIAN
100 *__SIMD32(pDst)++ = __PKHBT(__SSAT(-in1, 16), __SSAT(-in2, 16), 16);
105 *__SIMD32(pDst)++ = __PKHBT(__SSAT(-in2, 16), __SSAT(-in1, 16), 16);
107 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
109 /* Decrement the loop counter */
113 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
114 ** No loop unrolling is used. */
115 blkCnt = blockSize % 0x4u;
119 /* Run the below code for Cortex-M0 */
121 /* Initialize blkCnt with number of samples */
124 #endif /* #ifndef ARM_MATH_CM0 */
129 /* Negate and then store the result in the destination buffer. */
130 *pDst++ = __SSAT(-*pSrc++, 16);
132 /* Decrement the loop counter */
139 * @} end of negate group