
/*============================================================================

This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
Package, Release 3, by John R. Hauser.

Copyright 2011, 2012, 2013, 2014, 2015 The Regents of the University of
California (Regents).  All Rights Reserved.  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 two paragraphs of disclaimer.
Redistributions in binary form must reproduce the above copyright notice,
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the name of the Regents nor the names of its contributors may be used to
endorse or promote products derived from this software without specific prior
written permission.

IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
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REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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=============================================================================*/

#include <stdint.h>
#include "platform.h"

#ifndef softfloat_approxRecipSqrt32_1

uint32_t softfloat_approxRecipSqrt32_1( unsigned int oddExpA, uint32_t a )
{
    int index;
    uint16_t eps;
    static const uint16_t k0s[] = {
        0xB4C9, 0xFFAB, 0xAA7D, 0xF11C, 0xA1C5, 0xE4C7, 0x9A43, 0xDA29,
        0x93B5, 0xD0E5, 0x8DED, 0xC8B7, 0x88C6, 0xC16D, 0x8424, 0xBAE1
    };
    static const uint16_t k1s[] = {
        0xA5A5, 0xEA42, 0x8C21, 0xC62D, 0x788F, 0xAA7F, 0x6928, 0x94B6,
        0x5CC7, 0x8335, 0x52A6, 0x74E2, 0x4A3E, 0x68FE, 0x432B, 0x5EFD
    };
    uint16_t r0;
    uint_fast32_t ESqrR0;
    uint32_t delta0;
    uint_fast32_t r;
    uint32_t sqrDelta0;

    index = (a>>27 & 0xE) + oddExpA;
    eps = (uint16_t) (a>>12);
    r0 = k0s[index] - ((k1s[index] * (uint_fast32_t) eps)>>20);
    ESqrR0 = (uint_fast32_t) r0 * r0;
    if ( ! oddExpA ) ESqrR0 <<= 1;
    delta0 = ~(uint_fast32_t) (((uint32_t) ESqrR0 * (uint_fast64_t) a)>>23);
    r = ((uint_fast32_t) r0<<16) + ((r0 * (uint_fast64_t) delta0)>>25);
    sqrDelta0 = ((uint_fast64_t) delta0 * delta0)>>32;
    r += ((uint32_t) ((r>>1) + (r>>3) - ((uint_fast32_t) r0<<14))
              * (uint_fast64_t) sqrDelta0)
             >>48;
    if ( ! (r & 0x80000000) ) r = 0x80000000;
    return r;

}

#endif