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Diffstat (limited to 'tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c')
| -rw-r--r-- | tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c b/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c new file mode 100644 index 0000000000..7217834a86 --- /dev/null +++ b/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c @@ -0,0 +1,153 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2013 ARM Limited. All rights reserved. +* +* $Date: 17. January 2013 +* $Revision: V1.4.1 +* +* Project: CMSIS DSP Library +* Title: arm_sqrt_q31.c +* +* Description: Q31 square root function. +* +* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 +* +* Redistribution and use in source and binary forms, with or without +* modification, are permitted provided that the following conditions +* are met: +* - Redistributions of source code must retain the above copyright +* notice, this list of conditions and the following disclaimer. +* - Redistributions in binary form must reproduce the above copyright +* notice, this list of conditions and the following disclaimer in +* the documentation and/or other materials provided with the +* distribution. +* - Neither the name of ARM LIMITED nor the names of its contributors +* may be used to endorse or promote products derived from this +* software without specific prior written permission. +* +* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, +* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +* POSSIBILITY OF SUCH DAMAGE. +* -------------------------------------------------------------------- */ +#include "arm_math.h" +#include "arm_common_tables.h" + +/** + * @ingroup groupFastMath + */ + +/** + * @addtogroup SQRT + * @{ + */ + +/** + * @brief Q31 square root function. + * @param[in] in input value. The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF. + * @param[out] *pOut square root of input value. + * @return The function returns ARM_MATH_SUCCESS if the input value is positive + * and ARM_MATH_ARGUMENT_ERROR if the input is negative. For + * negative inputs, the function returns *pOut = 0. + */ + +arm_status arm_sqrt_q31( + q31_t in, + q31_t * pOut) +{ + q31_t number, temp1, bits_val1, var1, signBits1, half; + float32_t temp_float1; + union + { + q31_t fracval; + float32_t floatval; + } tempconv; + + number = in; + + /* If the input is a positive number then compute the signBits. */ + if(number > 0) + { + signBits1 = __CLZ(number) - 1; + + /* Shift by the number of signBits1 */ + if((signBits1 % 2) == 0) + { + number = number << signBits1; + } + else + { + number = number << (signBits1 - 1); + } + + /* Calculate half value of the number */ + half = number >> 1; + /* Store the number for later use */ + temp1 = number; + + /*Convert to float */ + temp_float1 = number * 4.6566128731e-010f; + /*Store as integer */ + tempconv.floatval = temp_float1; + bits_val1 = tempconv.fracval; + /* Subtract the shifted value from the magic number to give intial guess */ + bits_val1 = 0x5f3759df - (bits_val1 >> 1); // gives initial guess + /* Store as float */ + tempconv.fracval = bits_val1; + temp_float1 = tempconv.floatval; + /* Convert to integer format */ + var1 = (q31_t) (temp_float1 * 1073741824); + + /* 1st iteration */ + var1 = ((q31_t) ((q63_t) var1 * (0x30000000 - + ((q31_t) + ((((q31_t) + (((q63_t) var1 * var1) >> 31)) * + (q63_t) half) >> 31))) >> 31)) << 2; + /* 2nd iteration */ + var1 = ((q31_t) ((q63_t) var1 * (0x30000000 - + ((q31_t) + ((((q31_t) + (((q63_t) var1 * var1) >> 31)) * + (q63_t) half) >> 31))) >> 31)) << 2; + /* 3rd iteration */ + var1 = ((q31_t) ((q63_t) var1 * (0x30000000 - + ((q31_t) + ((((q31_t) + (((q63_t) var1 * var1) >> 31)) * + (q63_t) half) >> 31))) >> 31)) << 2; + + /* Multiply the inverse square root with the original value */ + var1 = ((q31_t) (((q63_t) temp1 * var1) >> 31)) << 1; + + /* Shift the output down accordingly */ + if((signBits1 % 2) == 0) + { + var1 = var1 >> (signBits1 / 2); + } + else + { + var1 = var1 >> ((signBits1 - 1) / 2); + } + *pOut = var1; + + return (ARM_MATH_SUCCESS); + } + /* If the number is a negative number then store zero as its square root value */ + else + { + *pOut = 0; + return (ARM_MATH_ARGUMENT_ERROR); + } +} + +/** + * @} end of SQRT group + */ |