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69 lines
2.7 KiB
C
69 lines
2.7 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_approxRecip32_1
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uint32_t softfloat_approxRecip32_1( 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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0xFFC4, 0xF0BE, 0xE363, 0xD76F, 0xCCAD, 0xC2F0, 0xBA16, 0xB201,
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0xAA97, 0xA3C6, 0x9D7A, 0x97A6, 0x923C, 0x8D32, 0x887E, 0x8417
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};
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static const uint16_t k1s[] = {
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0xF0F1, 0xD62C, 0xBFA1, 0xAC77, 0x9C0A, 0x8DDB, 0x8185, 0x76BA,
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0x6D3B, 0x64D4, 0x5D5C, 0x56B1, 0x50B6, 0x4B55, 0x4679, 0x4211
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};
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uint16_t r0;
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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 & 0xF;
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eps = (uint16_t) (a>>11);
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r0 = k0s[index] - ((k1s[index] * (uint_fast32_t) eps)>>20);
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delta0 = ~(uint_fast32_t) ((r0 * (uint_fast64_t) a)>>7);
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r = ((uint_fast32_t) r0<<16) + ((r0 * (uint_fast64_t) delta0)>>24);
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sqrDelta0 = ((uint_fast64_t) delta0 * delta0)>>32;
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r += ((uint32_t) r * (uint_fast64_t) sqrDelta0)>>48;
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return r;
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}
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#endif
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