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git.gir.st - tmk_keyboard.git/blob - tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_scale_f32.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_f32.c
10 * Description: Multiplies a floating-point 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 * ---------------------------------------------------------------------------- */
48 * @defgroup scale Vector Scale
50 * Multiply a vector by a scalar value. For floating-point data, the algorithm used is:
53 * pDst[n] = pSrc[n] * scale, 0 <= n < blockSize.
56 * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by
57 * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.
58 * The shift allows the gain of the scaling operation to exceed 1.0.
59 * The algorithm used with fixed-point data is:
62 * pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize.
65 * The overall scale factor applied to the fixed-point data is
67 * scale = scaleFract * 2^shift.
70 * The functions support in-place computation allowing the source and destination
71 * pointers to reference the same memory buffer.
80 * @brief Multiplies a floating-point vector by a scalar.
81 * @param[in] *pSrc points to the input vector
82 * @param[in] scale scale factor to be applied
83 * @param[out] *pDst points to the output vector
84 * @param[in] blockSize number of samples in the vector
95 uint32_t blkCnt
; /* loop counter */
96 #ifndef ARM_MATH_CM0_FAMILY
98 /* Run the below code for Cortex-M4 and Cortex-M3 */
99 float32_t in1
, in2
, in3
, in4
; /* temporary variabels */
102 blkCnt
= blockSize
>> 2u;
104 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
105 ** a second loop below computes the remaining 1 to 3 samples. */
109 /* Scale the input and then store the results in the destination buffer. */
110 /* read input samples from source */
114 /* multiply with scaling factor */
117 /* read input sample from source */
120 /* multiply with scaling factor */
123 /* read input sample from source */
126 /* multiply with scaling factor */
129 /* store the result to destination */
135 /* update pointers to process next samples */
139 /* Decrement the loop counter */
143 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
144 ** No loop unrolling is used. */
145 blkCnt
= blockSize
% 0x4u
;
149 /* Run the below code for Cortex-M0 */
151 /* Initialize blkCnt with number of samples */
154 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
159 /* Scale the input and then store the result in the destination buffer. */
160 *pDst
++ = (*pSrc
++) * scale
;
162 /* Decrement the loop counter */
168 * @} end of scale group