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/* ----------------------------------------------------------------------    
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/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*    
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*
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* $Date:        19. March 2015
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* $Date:        07. September 2015
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* $Revision:    V.1.4.5
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* $Revision:    V.1.4.5 a
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*    
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*
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* Project:          CMSIS DSP Library    
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* Project:      CMSIS DSP Library
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* Title:                arm_cos_q15.c    
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* Title:        arm_cos_q15.c
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*    
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*
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* Description:  Fast cosine calculation for Q15 values.  
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* Description:  Fast cosine calculation for Q15 values.
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*    
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*  
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*
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* Redistribution and use in source and binary forms, with or without
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* modification, are permitted provided that the following conditions
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* are met:
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* are met:
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*   - Redistributions of source code must retain the above copyright
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*   - Redistributions of source code must retain the above copyright
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*     notice, this list of conditions and the following disclaimer.
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*     notice, this list of conditions and the following disclaimer.
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*   - Redistributions in binary form must reproduce the above copyright
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*   - Redistributions in binary form must reproduce the above copyright
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*     notice, this list of conditions and the following disclaimer in
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*     notice, this list of conditions and the following disclaimer in
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*     the documentation and/or other materials provided with the
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*     the documentation and/or other materials provided with the
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*     distribution.
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*     distribution.
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*   - Neither the name of ARM LIMITED nor the names of its contributors
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*   - Neither the name of ARM LIMITED nor the names of its contributors
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*     may be used to endorse or promote products derived from this
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*     may be used to endorse or promote products derived from this
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*     software without specific prior written permission.
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*     software without specific prior written permission.
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*
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.  
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* POSSIBILITY OF SUCH DAMAGE.
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* -------------------------------------------------------------------- */
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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#include "arm_math.h"
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#include "arm_common_tables.h"
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#include "arm_common_tables.h"
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/**    
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/**
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 * @ingroup groupFastMath    
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 * @ingroup groupFastMath
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 */
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 */
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 /**    
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 /**
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 * @addtogroup cos    
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 * @addtogroup cos
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 * @{    
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 * @{
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 */
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 */
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/**  
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/**
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 * @brief Fast approximation to the trigonometric cosine function for Q15 data.  
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 * @brief Fast approximation to the trigonometric cosine function for Q15 data.
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 * @param[in] x Scaled input value in radians.  
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 * @param[in] x Scaled input value in radians.
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 * @return  cos(x).  
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 * @return  cos(x).
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 *  
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 *
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 * The Q15 input value is in the range [0 +0.9999] and is mapped to a radian
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 * The Q15 input value is in the range [0 +0.9999] and is mapped to a radian
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 * value in the range [0 2*pi).
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 * value in the range [0 2*pi).
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 */
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 */
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q15_t arm_cos_q15(
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q15_t arm_cos_q15(
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  q15_t x)
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  q15_t x)
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{
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{
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  q15_t sinVal;                                  /* Temporary variables for input, output */
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  q15_t cosVal;                                  /* Temporary variables for input, output */
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  int32_t index;                                 /* Index variables */
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  int32_t index;                                 /* Index variables */
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  q15_t a, b;                                    /* Four nearest output values */
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  q15_t a, b;                                    /* Four nearest output values */
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  q15_t fract;                                   /* Temporary values for fractional values */
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  q15_t fract;                                   /* Temporary values for fractional values */
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  /* add 0.25 (pi/2) to read sine table */
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  /* add 0.25 (pi/2) to read sine table */
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  x += 0x2000;
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  x = (uint16_t)x + 0x2000;
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  if(x < 0)
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  if(x < 0)
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  {   /* convert negative numbers to corresponding positive ones */
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  {   /* convert negative numbers to corresponding positive ones */
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      x = x + 0x8000;
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      x = (uint16_t)x + 0x8000;
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  }
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  }
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  /* Calculate the nearest index */
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  /* Calculate the nearest index */
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  index = (uint32_t)x >> FAST_MATH_Q15_SHIFT;
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  index = (uint32_t)x >> FAST_MATH_Q15_SHIFT;
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  /* Read two nearest values of input value from the sin table */
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  /* Read two nearest values of input value from the sin table */
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  a = sinTable_q15[index];
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  a = sinTable_q15[index];
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  b = sinTable_q15[index+1];
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  b = sinTable_q15[index+1];
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  /* Linear interpolation process */
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  /* Linear interpolation process */
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  sinVal = (q31_t)(0x8000-fract)*a >> 16;
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  cosVal = (q31_t)(0x8000-fract)*a >> 16;
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  sinVal = (q15_t)((((q31_t)sinVal << 16) + ((q31_t)fract*b)) >> 16);
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  cosVal = (q15_t)((((q31_t)cosVal << 16) + ((q31_t)fract*b)) >> 16);
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  return sinVal << 1;
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  return cosVal << 1;
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}
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}
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/**    
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/**
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 * @} end of cos group    
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 * @} end of cos group
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 */
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 */