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			252 lines
		
	
	
		
			6.9 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			252 lines
		
	
	
		
			6.9 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| /* ----------------------------------------------------------------------
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|  * Project:      CMSIS DSP Library
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|  * Title:        arm_shift_q15.c
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|  * Description:  Shifts the elements of a Q15 vector by a specified number of bits
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|  *
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|  * $Date:        23 April 2021
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|  * $Revision:    V1.9.0
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|  *
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|  * Target Processor: Cortex-M and Cortex-A cores
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|  * -------------------------------------------------------------------- */
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| /*
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|  * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
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|  *
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|  * SPDX-License-Identifier: Apache-2.0
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|  *
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|  * Licensed under the Apache License, Version 2.0 (the License); you may
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|  * not use this file except in compliance with the License.
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|  * You may obtain a copy of the License at
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|  *
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|  * www.apache.org/licenses/LICENSE-2.0
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|  *
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|  * Unless required by applicable law or agreed to in writing, software
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|  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
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|  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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|  * See the License for the specific language governing permissions and
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|  * limitations under the License.
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|  */
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| 
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| #include "dsp/basic_math_functions.h"
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| 
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| /**
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|   @ingroup groupMath
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|  */
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| 
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| /**
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|   @addtogroup BasicShift
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|   @{
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|  */
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| 
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| /**
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|   @brief         Shifts the elements of a Q15 vector a specified number of bits
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|   @param[in]     pSrc       points to the input vector
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|   @param[in]     shiftBits  number of bits to shift.  A positive value shifts left; a negative value shifts right.
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|   @param[out]    pDst       points to the output vector
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|   @param[in]     blockSize  number of samples in each vector
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|   @return        none
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| 
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|   @par           Scaling and Overflow Behavior
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|                    The function uses saturating arithmetic.
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|                    Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
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|  */
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| 
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| #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
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| 
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| #include "arm_helium_utils.h"
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| 
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| void arm_shift_q15(
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|     const q15_t * pSrc,
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|     int8_t shiftBits,
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|     q15_t * pDst,
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|     uint32_t blockSize)
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| {
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|     uint32_t  blkCnt;           /* loop counters */
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|     q15x8_t vecSrc;
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|     q15x8_t vecDst;
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| 
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|     /* Compute 8 outputs at a time */
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|     blkCnt = blockSize >> 3;
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|     while (blkCnt > 0U)
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|     {
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|         /*
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|          * C = A (>> or <<) shiftBits
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|          * Shift the input and then store the result in the destination buffer.
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|          */
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|         vecSrc = vld1q(pSrc);
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|         vecDst = vqshlq_r(vecSrc, shiftBits);
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|         vst1q(pDst, vecDst);
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|         /*
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|          * Decrement the blockSize loop counter
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|          */
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|         blkCnt--;
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|         /*
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|          * advance vector source and destination pointers
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|          */
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|         pSrc += 8;
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|         pDst += 8;
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|     }
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|     /*
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|      * tail
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|      */
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|     blkCnt = blockSize & 7;
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|     if (blkCnt > 0U)
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|     {
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|         mve_pred16_t p0 = vctp16q(blkCnt);
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|         vecSrc = vld1q(pSrc);
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|         vecDst = vqshlq_r(vecSrc, shiftBits);
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|         vstrhq_p(pDst, vecDst, p0);
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|     }
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| }
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| 
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| #else
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| void arm_shift_q15(
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|   const q15_t * pSrc,
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|         int8_t shiftBits,
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|         q15_t * pDst,
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|         uint32_t blockSize)
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| {
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|         uint32_t blkCnt;                               /* Loop counter */
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|         uint8_t sign = (shiftBits & 0x80);             /* Sign of shiftBits */
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| 
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| #if defined (ARM_MATH_LOOPUNROLL)
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| 
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| #if defined (ARM_MATH_DSP)
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|   q15_t in1, in2;                                /* Temporary input variables */
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| #endif
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| 
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|   /* Loop unrolling: Compute 4 outputs at a time */
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|   blkCnt = blockSize >> 2U;
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| 
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|   /* If the shift value is positive then do right shift else left shift */
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|   if (sign == 0U)
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|   {
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|     while (blkCnt > 0U)
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|     {
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|       /* C = A << shiftBits */
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| 
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| #if defined (ARM_MATH_DSP)
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|       /* read 2 samples from source */
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|       in1 = *pSrc++;
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|       in2 = *pSrc++;
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| 
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|       /* Shift the inputs and then store the results in the destination buffer. */
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| #ifndef ARM_MATH_BIG_ENDIAN
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|       write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in1 << shiftBits), 16),
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|                                      __SSAT(((q31_t) in2 << shiftBits), 16), 16));
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| #else
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|       write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in2 << shiftBits), 16),
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|                                       __SSAT(((q31_t) in1 << shiftBits), 16), 16));
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| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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| 
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|       /* read 2 samples from source */
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|       in1 = *pSrc++;
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|       in2 = *pSrc++;
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| 
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| #ifndef ARM_MATH_BIG_ENDIAN
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|       write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in1 << shiftBits), 16),
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|                                      __SSAT(((q31_t) in2 << shiftBits), 16), 16));
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| #else
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|       write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in2 << shiftBits), 16),
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|                                      __SSAT(((q31_t) in1 << shiftBits), 16), 16));
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| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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| 
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| #else
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|       *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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|       *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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|       *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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|       *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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| #endif
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| 
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|       /* Decrement loop counter */
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|       blkCnt--;
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|     }
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|   }
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|   else
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|   {
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|     while (blkCnt > 0U)
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|     {
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|       /* C = A >> shiftBits */
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| 
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| #if defined (ARM_MATH_DSP)
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|       /* read 2 samples from source */
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|       in1 = *pSrc++;
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|       in2 = *pSrc++;
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| 
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|       /* Shift the inputs and then store the results in the destination buffer. */
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| #ifndef ARM_MATH_BIG_ENDIAN
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|       write_q15x2_ia (&pDst, __PKHBT((in1 >> -shiftBits),
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|                                      (in2 >> -shiftBits), 16));
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| #else
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|       write_q15x2_ia (&pDst, __PKHBT((in2 >> -shiftBits),
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|                                      (in1 >> -shiftBits), 16));
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| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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| 
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|       /* read 2 samples from source */
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|       in1 = *pSrc++;
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|       in2 = *pSrc++;
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| 
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| #ifndef ARM_MATH_BIG_ENDIAN
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|       write_q15x2_ia (&pDst, __PKHBT((in1 >> -shiftBits),
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|                                      (in2 >> -shiftBits), 16));
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| #else
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|       write_q15x2_ia (&pDst, __PKHBT((in2 >> -shiftBits),
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|                                      (in1 >> -shiftBits), 16));
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| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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| 
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| #else
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|       *pDst++ = (*pSrc++ >> -shiftBits);
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|       *pDst++ = (*pSrc++ >> -shiftBits);
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|       *pDst++ = (*pSrc++ >> -shiftBits);
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|       *pDst++ = (*pSrc++ >> -shiftBits);
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| #endif
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| 
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|       /* Decrement loop counter */
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|       blkCnt--;
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|     }
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|   }
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| 
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|   /* Loop unrolling: Compute remaining outputs */
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|   blkCnt = blockSize % 0x4U;
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| 
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| #else
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| 
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|   /* Initialize blkCnt with number of samples */
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|   blkCnt = blockSize;
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| 
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| #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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| 
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|   /* If the shift value is positive then do right shift else left shift */
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|   if (sign == 0U)
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|   {
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|     while (blkCnt > 0U)
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|     {
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|       /* C = A << shiftBits */
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| 
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|       /* Shift input and store result in destination buffer. */
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|       *pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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| 
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|       /* Decrement loop counter */
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|       blkCnt--;
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|     }
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|   }
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|   else
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|   {
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|     while (blkCnt > 0U)
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|     {
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|       /* C = A >> shiftBits */
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| 
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|       /* Shift input and store result in destination buffer. */
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|       *pDst++ = (*pSrc++ >> -shiftBits);
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| 
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|       /* Decrement loop counter */
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|       blkCnt--;
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|     }
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|   }
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| 
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| }
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| #endif /* defined(ARM_MATH_MVEI) */
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| 
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| /**
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|   @} end of BasicShift group
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|  */
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