| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_shift_q15.c |
| * Description: Shifts the elements of a Q15 vector by a specified number of bits |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the License); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "arm_math.h" |
| |
| /** |
| @ingroup groupMath |
| */ |
| |
| /** |
| @addtogroup BasicShift |
| @{ |
| */ |
| |
| /** |
| @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 each vector |
| @return none |
| |
| @par Scaling and Overflow Behavior |
| The function uses saturating arithmetic. |
| Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated. |
| */ |
| |
| void arm_shift_q15( |
| const q15_t * pSrc, |
| int8_t shiftBits, |
| q15_t * pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| uint8_t sign = (shiftBits & 0x80); /* Sign of shiftBits */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| #if defined (ARM_MATH_DSP) |
| q15_t in1, in2; /* Temporary input variables */ |
| #endif |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| /* If the shift value is positive then do right shift else left shift */ |
| if (sign == 0U) |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A << shiftBits */ |
| |
| #if defined (ARM_MATH_DSP) |
| /* read 2 samples from source */ |
| in1 = *pSrc++; |
| in2 = *pSrc++; |
| |
| /* Shift the inputs and then store the results in the destination buffer. */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| write_q15x2_ia (&pDst, __PKHBT(__SSAT((in1 << shiftBits), 16), |
| __SSAT((in2 << shiftBits), 16), 16)); |
| #else |
| write_q15x2_ia (&pDst, __PKHBT(__SSAT((in2 << shiftBits), 16), |
| __SSAT((in1 << shiftBits), 16), 16)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* read 2 samples from source */ |
| in1 = *pSrc++; |
| in2 = *pSrc++; |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| write_q15x2_ia (&pDst, __PKHBT(__SSAT((in1 << shiftBits), 16), |
| __SSAT((in2 << shiftBits), 16), 16)); |
| #else |
| write_q15x2_ia (&pDst, __PKHBT(__SSAT((in2 << shiftBits), 16), |
| __SSAT((in1 << shiftBits), 16), 16)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| #else |
| *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16); |
| *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16); |
| *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16); |
| *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16); |
| #endif |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| else |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A >> shiftBits */ |
| |
| #if defined (ARM_MATH_DSP) |
| /* read 2 samples from source */ |
| in1 = *pSrc++; |
| in2 = *pSrc++; |
| |
| /* Shift the inputs and then store the results in the destination buffer. */ |
| #ifndef ARM_MATH_BIG_ENDIAN |
| write_q15x2_ia (&pDst, __PKHBT((in1 >> -shiftBits), |
| (in2 >> -shiftBits), 16)); |
| #else |
| write_q15x2_ia (&pDst, __PKHBT((in2 >> -shiftBits), |
| (in1 >> -shiftBits), 16)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* read 2 samples from source */ |
| in1 = *pSrc++; |
| in2 = *pSrc++; |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| write_q15x2_ia (&pDst, __PKHBT((in1 >> -shiftBits), |
| (in2 >> -shiftBits), 16)); |
| #else |
| write_q15x2_ia (&pDst, __PKHBT((in2 >> -shiftBits), |
| (in1 >> -shiftBits), 16)); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| #else |
| *pDst++ = (*pSrc++ >> -shiftBits); |
| *pDst++ = (*pSrc++ >> -shiftBits); |
| *pDst++ = (*pSrc++ >> -shiftBits); |
| *pDst++ = (*pSrc++ >> -shiftBits); |
| #endif |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| |
| /* Loop unrolling: Compute remaining outputs */ |
| blkCnt = blockSize % 0x4U; |
| |
| #else |
| |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = blockSize; |
| |
| #endif /* #if defined (ARM_MATH_LOOPUNROLL) */ |
| |
| /* If the shift value is positive then do right shift else left shift */ |
| if (sign == 0U) |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A << shiftBits */ |
| |
| /* Shift input and store result in destination buffer. */ |
| *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16); |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| else |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A >> shiftBits */ |
| |
| /* Shift input and store result in destination buffer. */ |
| *pDst++ = (*pSrc++ >> -shiftBits); |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| |
| } |
| |
| /** |
| @} end of BasicShift group |
| */ |