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_q7.c
10 * Description: Multiplies a Q7 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 Q7 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 1.7 format.
64 * These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.
74 int8_t kShift = 7 - shift; /* shift to apply after scaling */
75 uint32_t blkCnt; /* loop counter */
77 #ifndef ARM_MATH_CM0_FAMILY
79 /* Run the below code for Cortex-M4 and Cortex-M3 */
80 q7_t in1, in2, in3, in4, out1, out2, out3, out4; /* Temporary variables to store input & output */
84 blkCnt = blockSize >> 2u;
87 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
88 ** a second loop below computes the remaining 1 to 3 samples. */
91 /* Reading 4 inputs from memory */
98 /* Scale the inputs and then store the results in the temporary variables. */
99 out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8));
100 out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8));
101 out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8));
102 out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8));
104 /* Packing the individual outputs into 32bit and storing in
105 * destination buffer in single write */
106 *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
108 /* Decrement the loop counter */
112 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
113 ** No loop unrolling is used. */
114 blkCnt = blockSize % 0x4u;
119 /* Scale the input and then store the result in the destination buffer. */
120 *pDst++ = (q7_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 8));
122 /* Decrement the loop counter */
128 /* Run the below code for Cortex-M0 */
130 /* Initialize blkCnt with number of samples */
136 /* Scale the input and then store the result in the destination buffer. */
137 *pDst++ = (q7_t) (__SSAT((((q15_t) * pSrc++ * scaleFract) >> kShift), 8));
139 /* Decrement the loop counter */
143 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
148 * @} end of scale group