Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 1 | /* ===-- floatdixf.c - Implement __floatdixf -------------------------------=== |
| 2 | * |
| 3 | * The LLVM Compiler Infrastructure |
| 4 | * |
Howard Hinnant | 9ad441f | 2010-11-16 22:13:33 +0000 | [diff] [blame] | 5 | * This file is dual licensed under the MIT and the University of Illinois Open |
| 6 | * Source Licenses. See LICENSE.TXT for details. |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 7 | * |
| 8 | * ===----------------------------------------------------------------------=== |
| 9 | * |
| 10 | * This file implements __floatdixf for the compiler_rt library. |
| 11 | * |
| 12 | * ===----------------------------------------------------------------------=== |
| 13 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 14 | |
| 15 | #if !_ARCH_PPC |
| 16 | |
| 17 | #include "int_lib.h" |
| 18 | |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 19 | /* Returns: convert a to a long double, rounding toward even. */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 20 | |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 21 | /* Assumption: long double is a IEEE 80 bit floating point type padded to 128 bits |
| 22 | * di_int is a 64 bit integral type |
| 23 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 24 | |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 25 | /* gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee | |
| 26 | * 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm |
| 27 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 28 | |
| 29 | long double |
| 30 | __floatdixf(di_int a) |
| 31 | { |
| 32 | if (a == 0) |
| 33 | return 0.0; |
| 34 | const unsigned N = sizeof(di_int) * CHAR_BIT; |
| 35 | const di_int s = a >> (N-1); |
| 36 | a = (a ^ s) - s; |
| 37 | int clz = __builtin_clzll(a); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 38 | int e = (N - 1) - clz ; /* exponent */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 39 | long_double_bits fb; |
Edward O'Callaghan | 8bf1e09 | 2009-08-09 18:41:02 +0000 | [diff] [blame] | 40 | fb.u.high.s.low = ((su_int)s & 0x00008000) | /* sign */ |
| 41 | (e + 16383); /* exponent */ |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 42 | fb.u.low.all = a << clz; /* mantissa */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 43 | return fb.f; |
| 44 | } |
| 45 | |
Edward O'Callaghan | 8bf1e09 | 2009-08-09 18:41:02 +0000 | [diff] [blame] | 46 | #endif /* !_ARCH_PPC */ |