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Diffstat (limited to 'DSP_Lib/Source/BasicMathFunctions/arm_shift_q31.c')
-rw-r--r-- | DSP_Lib/Source/BasicMathFunctions/arm_shift_q31.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/DSP_Lib/Source/BasicMathFunctions/arm_shift_q31.c b/DSP_Lib/Source/BasicMathFunctions/arm_shift_q31.c new file mode 100644 index 0000000..5990491 --- /dev/null +++ b/DSP_Lib/Source/BasicMathFunctions/arm_shift_q31.c @@ -0,0 +1,203 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 19. March 2015 +* $Revision: V.1.4.5 +* +* Project: CMSIS DSP Library +* Title: arm_shift_q31.c +* +* Description: Shifts the elements of a Q31 vector by a specified number of bits. +* +* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 +* +* Redistribution and use in source and binary forms, with or without +* modification, are permitted provided that the following conditions +* are met: +* - Redistributions of source code must retain the above copyright +* notice, this list of conditions and the following disclaimer. +* - Redistributions in binary form must reproduce the above copyright +* notice, this list of conditions and the following disclaimer in +* the documentation and/or other materials provided with the +* distribution. +* - Neither the name of ARM LIMITED nor the names of its contributors +* may be used to endorse or promote products derived from this +* software without specific prior written permission. +* +* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, +* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +* POSSIBILITY OF SUCH DAMAGE. +* -------------------------------------------------------------------- */ + +#include "arm_math.h" + +/** + * @ingroup groupMath + */ +/** + * @defgroup shift Vector Shift + * + * Shifts the elements of a fixed-point vector by a specified number of bits. + * There are separate functions for Q7, Q15, and Q31 data types. + * The underlying algorithm used is: + * + * <pre> + * pDst[n] = pSrc[n] << shift, 0 <= n < blockSize. + * </pre> + * + * If <code>shift</code> is positive then the elements of the vector are shifted to the left. + * If <code>shift</code> is negative then the elements of the vector are shifted to the right. + * + * The functions support in-place computation allowing the source and destination + * pointers to reference the same memory buffer. + */ + +/** + * @addtogroup shift + * @{ + */ + +/** + * @brief Shifts the elements of a Q31 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 Q31 range [0x80000000 0x7FFFFFFF] will be saturated. + */ + +void arm_shift_q31( + q31_t * pSrc, + int8_t shiftBits, + q31_t * pDst, + uint32_t blockSize) +{ + uint32_t blkCnt; /* loop counter */ + uint8_t sign = (shiftBits & 0x80); /* Sign of shiftBits */ + +#ifndef ARM_MATH_CM0_FAMILY + + q31_t in1, in2, in3, in4; /* Temporary input variables */ + q31_t out1, out2, out3, out4; /* Temporary output variables */ + + /*loop Unrolling */ + blkCnt = blockSize >> 2u; + + + 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) + { + /* C = A << shiftBits */ + /* Shift the input and then store the results in the destination buffer. */ + in1 = *pSrc; + in2 = *(pSrc + 1); + out1 = in1 << shiftBits; + in3 = *(pSrc + 2); + out2 = in2 << shiftBits; + in4 = *(pSrc + 3); + if(in1 != (out1 >> shiftBits)) + out1 = 0x7FFFFFFF ^ (in1 >> 31); + + if(in2 != (out2 >> shiftBits)) + out2 = 0x7FFFFFFF ^ (in2 >> 31); + + *pDst = out1; + out3 = in3 << shiftBits; + *(pDst + 1) = out2; + out4 = in4 << shiftBits; + + if(in3 != (out3 >> shiftBits)) + out3 = 0x7FFFFFFF ^ (in3 >> 31); + + if(in4 != (out4 >> shiftBits)) + out4 = 0x7FFFFFFF ^ (in4 >> 31); + + *(pDst + 2) = out3; + *(pDst + 3) = out4; + + /* Update destination pointer to process next sampels */ + pSrc += 4u; + pDst += 4u; + + /* 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) + { + /* C = A >> shiftBits */ + /* Shift the input and then store the results in the destination buffer. */ + in1 = *pSrc; + in2 = *(pSrc + 1); + in3 = *(pSrc + 2); + in4 = *(pSrc + 3); + + *pDst = (in1 >> -shiftBits); + *(pDst + 1) = (in2 >> -shiftBits); + *(pDst + 2) = (in3 >> -shiftBits); + *(pDst + 3) = (in4 >> -shiftBits); + + + pSrc += 4u; + pDst += 4u; + + blkCnt--; + } + + } + + /* If the blockSize is not a multiple of 4, compute any remaining output samples here. + ** No loop unrolling is used. */ + blkCnt = blockSize % 0x4u; + +#else + + /* Run the below code for Cortex-M0 */ + + + /* Initialize blkCnt with number of samples */ + blkCnt = blockSize; + +#endif /* #ifndef ARM_MATH_CM0_FAMILY */ + + + while(blkCnt > 0u) + { + /* C = A (>> or <<) shiftBits */ + /* Shift the input and then store the result in the destination buffer. */ + *pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) : + (*pSrc++ >> -shiftBits); + + /* Decrement the loop counter */ + blkCnt--; + } + + +} + +/** + * @} end of shift group + */ |