GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcompiler_rt/floatdidf.c Lines: 0 4 0.0 %
Date: 2017-11-13 Branches: 0 0 0.0 %

Line Branch Exec Source
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/*===-- floatdidf.c - Implement __floatdidf -------------------------------===
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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 __floatdidf 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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/* 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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 *             di_int is a 64 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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ARM_EABI_FNALIAS(l2d, floatdidf)
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#ifndef __SOFT_FP__
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/* Support for systems that have hardware floating-point; we'll set the inexact flag
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 * as a side-effect of this computation.
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 */
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COMPILER_RT_ABI double
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__floatdidf(di_int a)
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{
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    static const double twop52 = 4503599627370496.0; // 0x1.0p52
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    static const double twop32 = 4294967296.0; // 0x1.0p32
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    union { int64_t x; double d; } low = { .d = twop52 };
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    const double high = (int32_t)(a >> 32) * twop32;
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    low.x |= a & INT64_C(0x00000000ffffffff);
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    const double result = (high - twop52) + low.d;
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    return result;
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}
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#else
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/* Support for systems that don't have hardware floating-point; there are no flags to
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 * set, and we don't want to code-gen to an unknown soft-float implementation.
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 */
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COMPILER_RT_ABI double
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__floatdidf(di_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(di_int) * CHAR_BIT;
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    const di_int s = a >> (N-1);
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    a = (a ^ s) - s;
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    int sd = N - __builtin_clzll(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 = ((du_int)a >> (sd - (DBL_MANT_DIG+2))) |
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                ((a & ((du_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 & ((du_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 = ((su_int)s & 0x80000000) |        /* sign */
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                  ((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