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git.gir.st - tmk_keyboard.git/blob - tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_scale_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_scale_q15.c
10 * Description: Multiplies a Q15 vector by a scalar.
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 Multiplies a Q15 vector by a scalar.
54 * @param[in] *pSrc points to the input vector
55 * @param[in] scaleFract fractional portion of the scale value
56 * @param[in] shift number of bits to shift the result by
57 * @param[out] *pDst points to the output vector
58 * @param[in] blockSize number of samples in the vector
61 * <b>Scaling and Overflow Behavior:</b>
63 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
64 * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
75 int8_t kShift
= 15 - shift
; /* shift to apply after scaling */
76 uint32_t blkCnt
; /* loop counter */
78 #ifndef ARM_MATH_CM0_FAMILY
80 /* Run the below code for Cortex-M4 and Cortex-M3 */
81 q15_t in1
, in2
, in3
, in4
;
82 q31_t inA1
, inA2
; /* Temporary variables */
83 q31_t out1
, out2
, out3
, out4
;
87 blkCnt
= blockSize
>> 2u;
89 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
90 ** a second loop below computes the remaining 1 to 3 samples. */
93 /* Reading 2 inputs from memory */
94 inA1
= *__SIMD32(pSrc
)++;
95 inA2
= *__SIMD32(pSrc
)++;
98 /* Scale the inputs and then store the 2 results in the destination buffer
99 * in single cycle by packing the outputs */
100 out1
= (q31_t
) ((q15_t
) (inA1
>> 16) * scaleFract
);
101 out2
= (q31_t
) ((q15_t
) inA1
* scaleFract
);
102 out3
= (q31_t
) ((q15_t
) (inA2
>> 16) * scaleFract
);
103 out4
= (q31_t
) ((q15_t
) inA2
* scaleFract
);
106 out1
= out1
>> kShift
;
107 out2
= out2
>> kShift
;
108 out3
= out3
>> kShift
;
109 out4
= out4
>> kShift
;
111 /* saturate the output */
112 in1
= (q15_t
) (__SSAT(out1
, 16));
113 in2
= (q15_t
) (__SSAT(out2
, 16));
114 in3
= (q15_t
) (__SSAT(out3
, 16));
115 in4
= (q15_t
) (__SSAT(out4
, 16));
117 /* store the result to destination */
118 *__SIMD32(pDst
)++ = __PKHBT(in2
, in1
, 16);
119 *__SIMD32(pDst
)++ = __PKHBT(in4
, in3
, 16);
121 /* Decrement the loop counter */
125 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
126 ** No loop unrolling is used. */
127 blkCnt
= blockSize
% 0x4u
;
132 /* Scale the input and then store the result in the destination buffer. */
133 *pDst
++ = (q15_t
) (__SSAT(((*pSrc
++) * scaleFract
) >> kShift
, 16));
135 /* Decrement the loop counter */
141 /* Run the below code for Cortex-M0 */
143 /* Initialize blkCnt with number of samples */
149 /* Scale the input and then store the result in the destination buffer. */
150 *pDst
++ = (q15_t
) (__SSAT(((q31_t
) * pSrc
++ * scaleFract
) >> kShift
, 16));
152 /* Decrement the loop counter */
156 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
161 * @} end of scale group