mirror of https://github.com/ARMmbed/mbed-os.git
153 lines
4.0 KiB
C
153 lines
4.0 KiB
C
/* ----------------------------------------------------------------------
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* Copyright (C) 2010 ARM Limited. All rights reserved.
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*
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* $Date: 15. February 2012
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* $Revision: V1.1.0
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*
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* Project: CMSIS DSP Library
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* Title: arm_abs_q7.c
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*
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* Description: Q7 vector absolute value.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Version 1.1.0 2012/02/15
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* Updated with more optimizations, bug fixes and minor API changes.
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*
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* Version 1.0.10 2011/7/15
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* Big Endian support added and Merged M0 and M3/M4 Source code.
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*
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* Version 1.0.3 2010/11/29
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* Re-organized the CMSIS folders and updated documentation.
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*
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* Version 1.0.2 2010/11/11
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* Documentation updated.
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*
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* Version 1.0.1 2010/10/05
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* Production release and review comments incorporated.
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*
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* Version 1.0.0 2010/09/20
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* Production release and review comments incorporated.
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*
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* Version 0.0.7 2010/06/10
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* Misra-C changes done
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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/**
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* @ingroup groupMath
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*/
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/**
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* @addtogroup BasicAbs
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* @{
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*/
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/**
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* @brief Q7 vector absolute value.
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* @param[in] *pSrc points to the input buffer
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* @param[out] *pDst points to the output buffer
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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 Conditions for optimum performance
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* Input and output buffers should be aligned by 32-bit
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*
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*
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* <b>Scaling and Overflow Behavior:</b>
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* \par
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* The function uses saturating arithmetic.
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* The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
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*/
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void arm_abs_q7(
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q7_t * pSrc,
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q7_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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q7_t in; /* Input value1 */
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#ifndef ARM_MATH_CM0
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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q31_t in1, in2, in3, in4; /* temporary input variables */
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q31_t out1, out2, out3, out4; /* temporary output variables */
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/*loop Unrolling */
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blkCnt = blockSize >> 2u;
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/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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** a second loop below computes the remaining 1 to 3 samples. */
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while(blkCnt > 0u)
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{
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/* C = |A| */
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/* Read inputs */
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in1 = (q31_t) * pSrc;
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in2 = (q31_t) * (pSrc + 1);
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in3 = (q31_t) * (pSrc + 2);
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/* find absolute value */
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out1 = (in1 > 0) ? in1 : __QSUB8(0, in1);
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/* read input */
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in4 = (q31_t) * (pSrc + 3);
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/* find absolute value */
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out2 = (in2 > 0) ? in2 : __QSUB8(0, in2);
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/* store result to destination */
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*pDst = (q7_t) out1;
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/* find absolute value */
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out3 = (in3 > 0) ? in3 : __QSUB8(0, in3);
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/* find absolute value */
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out4 = (in4 > 0) ? in4 : __QSUB8(0, in4);
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/* store result to destination */
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*(pDst + 1) = (q7_t) out2;
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/* store result to destination */
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*(pDst + 2) = (q7_t) out3;
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/* store result to destination */
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*(pDst + 3) = (q7_t) out4;
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/* update pointers to process next samples */
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pSrc += 4u;
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pDst += 4u;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
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** No loop unrolling is used. */
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blkCnt = blockSize % 0x4u;
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#else
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/* Run the below code for Cortex-M0 */
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blkCnt = blockSize;
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#endif // #define ARM_MATH_CM0
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while(blkCnt > 0u)
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{
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/* C = |A| */
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/* Read the input */
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in = *pSrc++;
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/* Store the Absolute result in the destination buffer */
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*pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
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/* Decrement the loop counter */
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blkCnt--;
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}
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}
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/**
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* @} end of BasicAbs group
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*/
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