1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010 ARM Limited. All rights reserved.
7 * Project: CMSIS DSP Library
8 * Title: arm_scale_q31.c
10 * Description: Multiplies a Q31 vector by a scalar.
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Version 1.0.10 2011/7/15
15 * Big Endian support added and Merged M0 and M3/M4 Source code.
17 * Version 1.0.3 2010/11/29
18 * Re-organized the CMSIS folders and updated documentation.
20 * Version 1.0.2 2010/11/11
21 * Documentation updated.
23 * Version 1.0.1 2010/10/05
24 * Production release and review comments incorporated.
26 * Version 1.0.0 2010/09/20
27 * Production release and review comments incorporated
29 * Version 0.0.7 2010/06/10
30 * Misra-C changes done
31 * -------------------------------------------------------------------- */
45 * @brief Multiplies a Q31 vector by a scalar.
46 * @param[in] *pSrc points to the input vector
47 * @param[in] scaleFract fractional portion of the scale value
48 * @param[in] shift number of bits to shift the result by
49 * @param[out] *pDst points to the output vector
50 * @param[in] blockSize number of samples in the vector
53 * <b>Scaling and Overflow Behavior:</b>
55 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.31 format.
56 * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.
66 int8_t kShift = 31 - shift; /* Shift to apply after scaling */
67 uint32_t blkCnt; /* loop counter */
71 /* Run the below code for Cortex-M4 and Cortex-M3 */
74 blkCnt = blockSize >> 2u;
76 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
77 ** a second loop below computes the remaining 1 to 3 samples. */
81 /* Scale the input and then store the results in the destination buffer. */
82 *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
83 *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
84 *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
85 *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
87 /* Decrement the loop counter */
91 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
92 ** No loop unrolling is used. */
93 blkCnt = blockSize % 0x4u;
97 /* Run the below code for Cortex-M0 */
99 /* Initialize blkCnt with number of samples */
102 #endif /* #ifndef ARM_MATH_CM0 */
107 /* Scale the input and then store the result in the destination buffer. */
108 *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
110 /* Decrement the loop counter */
116 * @} end of scale group