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Removed error on fat32 library, seems now to be able navigate among sectors in...
Removed error on fat32 library, seems now to be able navigate among sectors in both directions. Improved SDLCD drawing performances by almost 1000x.
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arm_sqrt_q15.c
178 lines | 5.3 KiB | text/x-c | CLexer
/ lib / src / stm32f4 / CPU / CMSIS / DSP_Lib / Source / FastMathFunctions / arm_sqrt_q15.c
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jeandet@pc-de-jeandet3.LAB-LPP.LOCAL
Added ARM CMSIS for fast math and circle drawing function for ili9328 driver.
 r41 /* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 15. July 2011
* $Revision: V1.0.10
*
* Project: CMSIS DSP Library
* Title: arm_sqrt_q15.c
*
* Description: Q15 square root function.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.0.10 2011/7/15
* Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
* Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
* Documentation updated.
*
* Version 1.0.1 2010/10/05
* Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
* Production release and review comments incorporated.
* -------------------------------------------------------------------- */
#include "arm_math.h"
#include "arm_common_tables.h"
/**
* @ingroup groupFastMath
*/
/**
* @addtogroup SQRT
* @{
*/
/**
* @brief Q15 square root function.
* @param[in] in input value. The range of the input value is [0 +1) or 0x0000 to 0x7FFF.
* @param[out] *pOut square root of input value.
* @return The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if
* <code>in</code> is negative value and returns zero output for negative values.
*/
arm_status arm_sqrt_q15(
q15_t in,
q15_t * pOut)
{
q31_t prevOut;
q15_t oneByOut;
uint32_t sign_bits;
#ifndef ARM_MATH_CM0
/* Run the below code for Cortex-M4 and Cortex-M3 */
q31_t out;
if(in > 0)
{
/* run for ten iterations */
/* Take initial guess as half of the input and first iteration */
out = ((q31_t) in >> 1u) + 0x3FFF;
/* Calculation of reciprocal of out */
/* oneByOut contains reciprocal of out which is in 2.14 format
and oneByOut should be upscaled by signBits */
sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
/* 0.5 * (out) */
out = out >> 1u;
/* prevOut = 0.5 * out + (in * (oneByOut << signBits))) */
prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
/* Third iteration */
sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
prevOut = prevOut >> 1u;
out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
out = out >> 1u;
prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
/* Fifth iteration */
sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
prevOut = prevOut >> 1u;
out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
out = out >> 1u;
prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
/* Seventh iteration */
sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
prevOut = prevOut >> 1u;
out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
out = out >> 1u;
prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
prevOut = prevOut >> 1u;
out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
/* tenth iteration */
sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
out = out >> 1u;
*pOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
return (ARM_MATH_SUCCESS);
}
#else
/* Run the below code for Cortex-M0 */
q31_t out, loopVar; /* Temporary variable for output, loop variable */
if(in > 0)
{
/* run for ten iterations */
/* Take initial guess as half of the input and first iteration */
out = ((q31_t) in >> 1u) + 0x3FFF;
/* Calculation of reciprocal of out */
/* oneByOut contains reciprocal of out which is in 2.14 format
and oneByOut should be upscaled by sign bits */
sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
/* 0.5 * (out) */
out = out >> 1u;
/* prevOut = 0.5 * out + (in * oneByOut) << signbits))) */
prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
/* loop for third iteration to tenth iteration */
for (loopVar = 1; loopVar <= 8; loopVar++)
{
sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
/* 0.5 * (prevOut) */
prevOut = prevOut >> 1u;
/* prevOut = 0.5 * prevOut+ (in * oneByOut) << signbits))) */
out =
prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
/* prevOut = out */
prevOut = out;
}
/* output is moved to pOut pointer */
*pOut = prevOut;
return (ARM_MATH_SUCCESS);
}
#endif /* #ifndef ARM_MATH_CM0 */
else
{
*pOut = 0;
return (ARM_MATH_ARGUMENT_ERROR);
}
}
/**
* @} end of SQRT group
*/