CMSIS DSP Library from CMSIS 2.0. See http://www.onarm.com/cmsis/ for full details
Dependents: K22F_DSP_Matrix_least_square BNO055-ELEC3810 1BNO055 ECE4180Project--Slave2 ... more
src/Cortex-M4-M3/BasicMathFunctions/arm_scale_q31.c
- Committer:
- simon
- Date:
- 2011-03-10
- Revision:
- 0:1014af42efd9
File content as of revision 0:1014af42efd9:
/* ---------------------------------------------------------------------- * Copyright (C) 2010 ARM Limited. All rights reserved. * * $Date: 29. November 2010 * $Revision: V1.0.3 * * Project: CMSIS DSP Library * Title: arm_scale_q31.c * * Description: Multiplies a Q31 vector by a scalar. * * Target Processor: Cortex-M4/Cortex-M3 * * Version 1.0.3 2010/11/29 * Re-organized the CMSIS folders and updated documentation. * * Version 1.0.2 2010/11/11 * Documentation updated. * * Version 1.0.1 2010/10/05 * Production release and review comments incorporated. * * Version 1.0.0 2010/09/20 * Production release and review comments incorporated * * Version 0.0.7 2010/06/10 * Misra-C changes done * -------------------------------------------------------------------- */ #include "arm_math.h" /** * @ingroup groupMath */ /** * @addtogroup scale * @{ */ /** * @brief Multiplies a Q31 vector by a scalar. * @param[in] *pSrc points to the input vector * @param[in] scaleFract fractional portion of the scale value * @param[in] shift number of bits to shift the result by * @param[out] *pDst points to the output vector * @param[in] blockSize number of samples in the vector * @return none. * * <b>Scaling and Overflow Behavior:</b> * \par * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.31 format. * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format. */ void arm_scale_q31( q31_t * pSrc, q31_t scaleFract, int8_t shift, q31_t * pDst, uint32_t blockSize) { int8_t kShift = 31 - shift; /* Shift to apply after scaling */ uint32_t blkCnt; /* loop counter */ /*loop Unrolling */ blkCnt = blockSize >> 2u; /* First part of the processing with loop unrolling. Compute 4 outputs at a time. ** a second loop below computes the remaining 1 to 3 samples. */ while(blkCnt > 0u) { /* C = A * scale */ /* Scale the input and then store the results in the destination buffer. */ *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift); *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift); *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift); *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift); /* Decrement the loop counter */ blkCnt--; } /* If the blockSize is not a multiple of 4, compute any remaining output samples here. ** No loop unrolling is used. */ blkCnt = blockSize % 0x4u; while(blkCnt > 0u) { /* C = A * scale */ /* Scale the input and then store the result in the destination buffer. */ *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift); /* Decrement the loop counter */ blkCnt--; } } /** * @} end of scale group */