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75 lines
3.0 KiB
C
75 lines
3.0 KiB
C
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/*============================================================================
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This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
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Package, Release 3, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014, 2015 The Regents of the University of
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California (Regents). All Rights Reserved. Redistribution and use in source
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and binary forms, with or without modification, are permitted provided that
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the following conditions are met:
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Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following two paragraphs of disclaimer.
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Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following two paragraphs of disclaimer in the
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documentation and/or other materials provided with the distribution. Neither
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the name of the Regents nor the names of its contributors may be used to
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endorse or promote products derived from this software without specific prior
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written permission.
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IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
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SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
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OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
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BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
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HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
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MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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=============================================================================*/
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#include <stdint.h>
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#include "platform.h"
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#ifndef softfloat_approxRecipSqrt32_1
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uint32_t softfloat_approxRecipSqrt32_1( unsigned int oddExpA, uint32_t a )
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{
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int index;
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uint16_t eps;
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static const uint16_t k0s[] = {
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0xB4C9, 0xFFAB, 0xAA7D, 0xF11C, 0xA1C5, 0xE4C7, 0x9A43, 0xDA29,
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0x93B5, 0xD0E5, 0x8DED, 0xC8B7, 0x88C6, 0xC16D, 0x8424, 0xBAE1
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};
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static const uint16_t k1s[] = {
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0xA5A5, 0xEA42, 0x8C21, 0xC62D, 0x788F, 0xAA7F, 0x6928, 0x94B6,
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0x5CC7, 0x8335, 0x52A6, 0x74E2, 0x4A3E, 0x68FE, 0x432B, 0x5EFD
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};
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uint16_t r0;
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uint_fast32_t ESqrR0;
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uint32_t delta0;
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uint_fast32_t r;
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uint32_t sqrDelta0;
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index = (a>>27 & 0xE) + oddExpA;
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eps = (uint16_t) (a>>12);
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r0 = k0s[index] - ((k1s[index] * (uint_fast32_t) eps)>>20);
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ESqrR0 = (uint_fast32_t) r0 * r0;
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if ( ! oddExpA ) ESqrR0 <<= 1;
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delta0 = ~(uint_fast32_t) (((uint32_t) ESqrR0 * (uint_fast64_t) a)>>23);
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r = ((uint_fast32_t) r0<<16) + ((r0 * (uint_fast64_t) delta0)>>25);
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sqrDelta0 = ((uint_fast64_t) delta0 * delta0)>>32;
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r += ((uint32_t) ((r>>1) + (r>>3) - ((uint_fast32_t) r0<<14))
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* (uint_fast64_t) sqrDelta0)
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>>48;
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if ( ! (r & 0x80000000) ) r = 0x80000000;
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return r;
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}
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#endif
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