1 /* ===-- floatdixf.c - Implement __floatdixf -------------------------------=== 2 * 3 * The LLVM Compiler Infrastructure 4 * 5 * This file is dual licensed under the MIT and the University of Illinois Open 6 * Source Licenses. See LICENSE.TXT for details. 7 * 8 * ===----------------------------------------------------------------------=== 9 * 10 * This file implements __floatdixf for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #if !_ARCH_PPC 16 17 #include "int_lib.h" 18 19 /* Returns: convert a to a long double, rounding toward even. */ 20 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 */ 24 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 */ 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); 38 int e = (N - 1) - clz ; /* exponent */ 39 long_double_bits fb; 40 fb.u.high.s.low = ((su_int)s & 0x00008000) | /* sign */ 41 (e + 16383); /* exponent */ 42 fb.u.low.all = a << clz; /* mantissa */ 43 return fb.f; 44 } 45 46 #endif /* !_ARCH_PPC */ 47
