GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcompiler_rt/floatuntidf.c Lines: 0 19 0.0 %
Date: 2017-11-07 Branches: 0 9 0.0 %

Line Branch Exec Source
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/* ===-- floatuntidf.c - Implement __floatuntidf ---------------------------===
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 *
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 *                     The LLVM Compiler Infrastructure
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 *
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 * This file is dual licensed under the MIT and the University of Illinois Open
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 * Source Licenses. See LICENSE.TXT for details.
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 *
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 * ===----------------------------------------------------------------------===
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 *
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 * This file implements __floatuntidf for the compiler_rt library.
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 *
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 * ===----------------------------------------------------------------------===
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 */
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#include "int_lib.h"
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#ifdef CRT_HAS_128BIT
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/* Returns: convert a to a double, rounding toward even. */
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/* Assumption: double is a IEEE 64 bit floating point type
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 *             tu_int is a 128 bit integral type
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 */
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/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
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COMPILER_RT_ABI double
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__floatuntidf(tu_int a)
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{
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    if (a == 0)
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        return 0.0;
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    const unsigned N = sizeof(tu_int) * CHAR_BIT;
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    int sd = N - __clzti2(a);  /* number of significant digits */
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    int e = sd - 1;             /* exponent */
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    if (sd > DBL_MANT_DIG)
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    {
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        /*  start:  0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
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         *  finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
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         *                                                12345678901234567890123456
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         *  1 = msb 1 bit
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         *  P = bit DBL_MANT_DIG-1 bits to the right of 1
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         *  Q = bit DBL_MANT_DIG bits to the right of 1
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         *  R = "or" of all bits to the right of Q
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         */
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        switch (sd)
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        {
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        case DBL_MANT_DIG + 1:
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            a <<= 1;
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            break;
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        case DBL_MANT_DIG + 2:
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            break;
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        default:
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            a = (a >> (sd - (DBL_MANT_DIG+2))) |
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                ((a & ((tu_int)(-1) >> ((N + DBL_MANT_DIG+2) - sd))) != 0);
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        };
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        /* finish: */
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        a |= (a & 4) != 0;  /* Or P into R */
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        ++a;  /* round - this step may add a significant bit */
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        a >>= 2;  /* dump Q and R */
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        /* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */
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        if (a & ((tu_int)1 << DBL_MANT_DIG))
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        {
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            a >>= 1;
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            ++e;
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        }
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        /* a is now rounded to DBL_MANT_DIG bits */
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    }
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    else
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    {
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        a <<= (DBL_MANT_DIG - sd);
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        /* a is now rounded to DBL_MANT_DIG bits */
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    }
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    double_bits fb;
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    fb.u.s.high = ((e + 1023) << 20)      |        /* exponent */
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                ((su_int)(a >> 32) & 0x000FFFFF); /* mantissa-high */
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    fb.u.s.low = (su_int)a;                         /* mantissa-low */
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    return fb.f;
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}
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#endif /* CRT_HAS_128BIT */