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git.gir.st - tmk_keyboard.git/blob - tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_shift_q15.c
1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
8 * Title: arm_shift_q15.c
10 * Description: Shifts the elements of a Q15 vector by a specified number of bits.
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
17 * - Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * - Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in
21 * the documentation and/or other materials provided with the
23 * - Neither the name of ARM LIMITED nor the names of its contributors
24 * may be used to endorse or promote products derived from this
25 * software without specific prior written permission.
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 * -------------------------------------------------------------------- */
53 * @brief Shifts the elements of a Q15 vector a specified number of bits.
54 * @param[in] *pSrc points to the input vector
55 * @param[in] shiftBits number of bits to shift. A positive value shifts left; a negative value shifts right.
56 * @param[out] *pDst points to the output vector
57 * @param[in] blockSize number of samples in the vector
60 * <b>Scaling and Overflow Behavior:</b>
62 * The function uses saturating arithmetic.
63 * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
72 uint32_t blkCnt
; /* loop counter */
73 uint8_t sign
; /* Sign of shiftBits */
75 #ifndef ARM_MATH_CM0_FAMILY
77 /* Run the below code for Cortex-M4 and Cortex-M3 */
79 q15_t in1
, in2
; /* Temporary variables */
83 blkCnt
= blockSize
>> 2u;
85 /* Getting the sign of shiftBits */
86 sign
= (shiftBits
& 0x80);
88 /* If the shift value is positive then do right shift else left shift */
91 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
92 ** a second loop below computes the remaining 1 to 3 samples. */
98 /* C = A << shiftBits */
99 /* Shift the inputs and then store the results in the destination buffer. */
100 #ifndef ARM_MATH_BIG_ENDIAN
102 *__SIMD32(pDst
)++ = __PKHBT(__SSAT((in1
<< shiftBits
), 16),
103 __SSAT((in2
<< shiftBits
), 16), 16);
107 *__SIMD32(pDst
)++ = __PKHBT(__SSAT((in2
<< shiftBits
), 16),
108 __SSAT((in1
<< shiftBits
), 16), 16);
110 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
115 #ifndef ARM_MATH_BIG_ENDIAN
117 *__SIMD32(pDst
)++ = __PKHBT(__SSAT((in1
<< shiftBits
), 16),
118 __SSAT((in2
<< shiftBits
), 16), 16);
122 *__SIMD32(pDst
)++ = __PKHBT(__SSAT((in2
<< shiftBits
), 16),
123 __SSAT((in1
<< shiftBits
), 16), 16);
125 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
127 /* Decrement the loop counter */
131 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
132 ** No loop unrolling is used. */
133 blkCnt
= blockSize
% 0x4u
;
137 /* C = A << shiftBits */
138 /* Shift and then store the results in the destination buffer. */
139 *pDst
++ = __SSAT((*pSrc
++ << shiftBits
), 16);
141 /* Decrement the loop counter */
147 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
148 ** a second loop below computes the remaining 1 to 3 samples. */
155 /* C = A >> shiftBits */
156 /* Shift the inputs and then store the results in the destination buffer. */
157 #ifndef ARM_MATH_BIG_ENDIAN
159 *__SIMD32(pDst
)++ = __PKHBT((in1
>> -shiftBits
),
160 (in2
>> -shiftBits
), 16);
164 *__SIMD32(pDst
)++ = __PKHBT((in2
>> -shiftBits
),
165 (in1
>> -shiftBits
), 16);
167 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
172 #ifndef ARM_MATH_BIG_ENDIAN
174 *__SIMD32(pDst
)++ = __PKHBT((in1
>> -shiftBits
),
175 (in2
>> -shiftBits
), 16);
179 *__SIMD32(pDst
)++ = __PKHBT((in2
>> -shiftBits
),
180 (in1
>> -shiftBits
), 16);
182 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
184 /* Decrement the loop counter */
188 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
189 ** No loop unrolling is used. */
190 blkCnt
= blockSize
% 0x4u
;
194 /* C = A >> shiftBits */
195 /* Shift the inputs and then store the results in the destination buffer. */
196 *pDst
++ = (*pSrc
++ >> -shiftBits
);
198 /* Decrement the loop counter */
205 /* Run the below code for Cortex-M0 */
207 /* Getting the sign of shiftBits */
208 sign
= (shiftBits
& 0x80);
210 /* If the shift value is positive then do right shift else left shift */
213 /* Initialize blkCnt with number of samples */
218 /* C = A << shiftBits */
219 /* Shift and then store the results in the destination buffer. */
220 *pDst
++ = __SSAT(((q31_t
) * pSrc
++ << shiftBits
), 16);
222 /* Decrement the loop counter */
228 /* Initialize blkCnt with number of samples */
233 /* C = A >> shiftBits */
234 /* Shift the inputs and then store the results in the destination buffer. */
235 *pDst
++ = (*pSrc
++ >> -shiftBits
);
237 /* Decrement the loop counter */
242 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
247 * @} end of shift group