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Diffstat (limited to 'platform/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c')
| -rw-r--r-- | platform/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/platform/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c b/platform/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c new file mode 100644 index 0000000..911aa2f --- /dev/null +++ b/platform/CMSIS/DSP_Lib/Source/SupportFunctions/arm_q31_to_q15.c @@ -0,0 +1,145 @@ +/* ---------------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 31. July 2014 +* $Revision: V1.4.4 +* +* Project: CMSIS DSP Library +* Title: arm_q31_to_q15.c +* +* Description: Converts the elements of the Q31 vector to Q15 vector. +* +* 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 groupSupport + */ + +/** + * @addtogroup q31_to_x + * @{ + */ + +/** + * @brief Converts the elements of the Q31 vector to Q15 vector. + * @param[in] *pSrc points to the Q31 input vector + * @param[out] *pDst points to the Q15 output vector + * @param[in] blockSize length of the input vector + * @return none. + * + * \par Description: + * + * The equation used for the conversion process is: + * + * <pre> + * pDst[n] = (q15_t) pSrc[n] >> 16; 0 <= n < blockSize. + * </pre> + * + */ + + +void arm_q31_to_q15( + q31_t * pSrc, + q15_t * pDst, + uint32_t blockSize) +{ + q31_t *pIn = pSrc; /* Src pointer */ + uint32_t blkCnt; /* loop counter */ + +#ifndef ARM_MATH_CM0_FAMILY + + /* Run the below code for Cortex-M4 and Cortex-M3 */ + q31_t in1, in2, in3, in4; + q31_t out1, out2; + + /*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 = (q15_t) A >> 16 */ + /* convert from q31 to q15 and then store the results in the destination buffer */ + in1 = *pIn++; + in2 = *pIn++; + in3 = *pIn++; + in4 = *pIn++; + + /* pack two higher 16-bit values from two 32-bit values */ +#ifndef ARM_MATH_BIG_ENDIAN + + out1 = __PKHTB(in2, in1, 16); + out2 = __PKHTB(in4, in3, 16); + +#else + + out1 = __PKHTB(in1, in2, 16); + out2 = __PKHTB(in3, in4, 16); + +#endif // #ifdef ARM_MATH_BIG_ENDIAN + + *__SIMD32(pDst)++ = out1; + *__SIMD32(pDst)++ = out2; + + /* 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; + +#else + + /* Run the below code for Cortex-M0 */ + + /* Loop over blockSize number of values */ + blkCnt = blockSize; + +#endif /* #ifndef ARM_MATH_CM0_FAMILY */ + + while(blkCnt > 0u) + { + /* C = (q15_t) A >> 16 */ + /* convert from q31 to q15 and then store the results in the destination buffer */ + *pDst++ = (q15_t) (*pIn++ >> 16); + + /* Decrement the loop counter */ + blkCnt--; + } + +} + +/** + * @} end of q31_to_x group + */ |