/CMSIS/DSP_Lib/Source/BasicMathFunctions/arm_shift_q15.c
C | 243 lines | 97 code | 52 blank | 94 comment | 4 complexity | 4e0921855206da24a437d2f2a78d1db8 MD5 | raw file
- /* ----------------------------------------------------------------------
- * Copyright (C) 2010 ARM Limited. All rights reserved.
- *
- * $Date: 15. February 2012
- * $Revision: V1.1.0
- *
- * Project: CMSIS DSP Library
- * Title: arm_shift_q15.c
- *
- * Description: Shifts the elements of a Q15 vector by a specified number of bits.
- *
- * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
- *
- * Version 1.1.0 2012/02/15
- * Updated with more optimizations, bug fixes and minor API changes.
- *
- * Version 1.0.10 2011/7/15
- * Big Endian support added and Merged M0 and M3/M4 Source code.
- *
- * 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 shift
- * @{
- */
- /**
- * @brief Shifts the elements of a Q15 vector a specified number of bits.
- * @param[in] *pSrc points to the input vector
- * @param[in] shiftBits number of bits to shift. A positive value shifts left; a negative value shifts right.
- * @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 function uses saturating arithmetic.
- * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
- */
- void arm_shift_q15(
- q15_t * pSrc,
- int8_t shiftBits,
- q15_t * pDst,
- uint32_t blockSize)
- {
- uint32_t blkCnt; /* loop counter */
- uint8_t sign; /* Sign of shiftBits */
- #ifndef ARM_MATH_CM0
- /* Run the below code for Cortex-M4 and Cortex-M3 */
- q15_t in1, in2; /* Temporary variables */
- /*loop Unrolling */
- blkCnt = blockSize >> 2u;
- /* Getting the sign of shiftBits */
- sign = (shiftBits & 0x80);
- /* If the shift value is positive then do right shift else left shift */
- if(sign == 0u)
- {
- /* 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)
- {
- /* Read 2 inputs */
- in1 = *pSrc++;
- in2 = *pSrc++;
- /* C = A << shiftBits */
- /* Shift the inputs and then store the results in the destination buffer. */
- #ifndef ARM_MATH_BIG_ENDIAN
- *__SIMD32(pDst)++ = __PKHBT(__SSAT((in1 << shiftBits), 16),
- __SSAT((in2 << shiftBits), 16), 16);
- #else
- *__SIMD32(pDst)++ = __PKHBT(__SSAT((in2 << shiftBits), 16),
- __SSAT((in1 << shiftBits), 16), 16);
- #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
- in1 = *pSrc++;
- in2 = *pSrc++;
- #ifndef ARM_MATH_BIG_ENDIAN
- *__SIMD32(pDst)++ = __PKHBT(__SSAT((in1 << shiftBits), 16),
- __SSAT((in2 << shiftBits), 16), 16);
- #else
- *__SIMD32(pDst)++ = __PKHBT(__SSAT((in2 << shiftBits), 16),
- __SSAT((in1 << shiftBits), 16), 16);
- #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
- /* 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 << shiftBits */
- /* Shift and then store the results in the destination buffer. */
- *pDst++ = __SSAT((*pSrc++ << shiftBits), 16);
- /* Decrement the loop counter */
- blkCnt--;
- }
- }
- else
- {
- /* 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)
- {
- /* Read 2 inputs */
- in1 = *pSrc++;
- in2 = *pSrc++;
- /* C = A >> shiftBits */
- /* Shift the inputs and then store the results in the destination buffer. */
- #ifndef ARM_MATH_BIG_ENDIAN
- *__SIMD32(pDst)++ = __PKHBT((in1 >> -shiftBits),
- (in2 >> -shiftBits), 16);
- #else
- *__SIMD32(pDst)++ = __PKHBT((in2 >> -shiftBits),
- (in1 >> -shiftBits), 16);
- #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
- in1 = *pSrc++;
- in2 = *pSrc++;
- #ifndef ARM_MATH_BIG_ENDIAN
- *__SIMD32(pDst)++ = __PKHBT((in1 >> -shiftBits),
- (in2 >> -shiftBits), 16);
- #else
- *__SIMD32(pDst)++ = __PKHBT((in2 >> -shiftBits),
- (in1 >> -shiftBits), 16);
- #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
- /* 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 >> shiftBits */
- /* Shift the inputs and then store the results in the destination buffer. */
- *pDst++ = (*pSrc++ >> -shiftBits);
- /* Decrement the loop counter */
- blkCnt--;
- }
- }
- #else
- /* Run the below code for Cortex-M0 */
- /* Getting the sign of shiftBits */
- sign = (shiftBits & 0x80);
- /* If the shift value is positive then do right shift else left shift */
- if(sign == 0u)
- {
- /* Initialize blkCnt with number of samples */
- blkCnt = blockSize;
- while(blkCnt > 0u)
- {
- /* C = A << shiftBits */
- /* Shift and then store the results in the destination buffer. */
- *pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);
- /* Decrement the loop counter */
- blkCnt--;
- }
- }
- else
- {
- /* Initialize blkCnt with number of samples */
- blkCnt = blockSize;
- while(blkCnt > 0u)
- {
- /* C = A >> shiftBits */
- /* Shift the inputs and then store the results in the destination buffer. */
- *pDst++ = (*pSrc++ >> -shiftBits);
- /* Decrement the loop counter */
- blkCnt--;
- }
- }
- #endif /* #ifndef ARM_MATH_CM0 */
- }
- /**
- * @} end of shift group
- */