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git.gir.st - tmk_keyboard.git/blob - tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_abs_q7.c
1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
10 * Description: Q7 vector absolute value.
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 * -------------------------------------------------------------------- */
48 * @addtogroup BasicAbs
53 * @brief Q7 vector absolute value.
54 * @param[in] *pSrc points to the input buffer
55 * @param[out] *pDst points to the output buffer
56 * @param[in] blockSize number of samples in each vector
59 * \par Conditions for optimum performance
60 * Input and output buffers should be aligned by 32-bit
63 * <b>Scaling and Overflow Behavior:</b>
65 * The function uses saturating arithmetic.
66 * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
74 uint32_t blkCnt
; /* loop counter */
75 q7_t in
; /* Input value1 */
77 #ifndef ARM_MATH_CM0_FAMILY
79 /* Run the below code for Cortex-M4 and Cortex-M3 */
80 q31_t in1
, in2
, in3
, in4
; /* temporary input variables */
81 q31_t out1
, out2
, out3
, out4
; /* temporary output variables */
84 blkCnt
= blockSize
>> 2u;
86 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
87 ** a second loop below computes the remaining 1 to 3 samples. */
93 in2
= (q31_t
) * (pSrc
+ 1);
94 in3
= (q31_t
) * (pSrc
+ 2);
96 /* find absolute value */
97 out1
= (in1
> 0) ? in1
: (q31_t
)__QSUB8(0, in1
);
100 in4
= (q31_t
) * (pSrc
+ 3);
102 /* find absolute value */
103 out2
= (in2
> 0) ? in2
: (q31_t
)__QSUB8(0, in2
);
105 /* store result to destination */
108 /* find absolute value */
109 out3
= (in3
> 0) ? in3
: (q31_t
)__QSUB8(0, in3
);
111 /* find absolute value */
112 out4
= (in4
> 0) ? in4
: (q31_t
)__QSUB8(0, in4
);
114 /* store result to destination */
115 *(pDst
+ 1) = (q7_t
) out2
;
117 /* store result to destination */
118 *(pDst
+ 2) = (q7_t
) out3
;
120 /* store result to destination */
121 *(pDst
+ 3) = (q7_t
) out4
;
123 /* update pointers to process next samples */
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
;
136 /* Run the below code for Cortex-M0 */
139 #endif // #define ARM_MATH_CM0_FAMILY
147 /* Store the Absolute result in the destination buffer */
148 *pDst
++ = (in
> 0) ? in
: ((in
== (q7_t
) 0x80) ? 0x7f : -in
);
150 /* Decrement the loop counter */
156 * @} end of BasicAbs group