diff options
Diffstat (limited to 'lib/floatundidf.c')
-rw-r--r-- | lib/floatundidf.c | 84 |
1 files changed, 45 insertions, 39 deletions
diff --git a/lib/floatundidf.c b/lib/floatundidf.c index 708d614ac..1f304c5c3 100644 --- a/lib/floatundidf.c +++ b/lib/floatundidf.c @@ -1,29 +1,33 @@ -//===-- floatundidf.c - Implement __floatundidf ---------------------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file implements __floatundidf for the compiler_rt library. -// -//===----------------------------------------------------------------------===// +/* ===-- floatundidf.c - Implement __floatundidf ---------------------------=== + * + * The LLVM Compiler Infrastructure + * + * This file is distributed under the University of Illinois Open Source + * License. See LICENSE.TXT for details. + * + * ===----------------------------------------------------------------------=== + * + * This file implements __floatundidf for the compiler_rt library. + * + * ===----------------------------------------------------------------------=== + */ #include "int_lib.h" #include <float.h> -// Returns: convert a to a double, rounding toward even. +/* Returns: convert a to a double, rounding toward even. */ -// Assumption: double is a IEEE 64 bit floating point type -// du_int is a 64 bit integral type +/* Assumption: double is a IEEE 64 bit floating point type + * du_int is a 64 bit integral type + */ -// seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm +/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */ #ifndef __SOFT_FP__ -// Support for systems that have hardware floating-point; we'll set the inexact flag -// as a side-effect of this computation. +/* Support for systems that have hardware floating-point; we'll set the inexact flag + * as a side-effect of this computation. + */ + #include <stdint.h> double @@ -44,8 +48,9 @@ __floatundidf(du_int a) } #else -// Support for systems that don't have hardware floating-point; there are no flags to -// set, and we don't want to code-gen to an unknown soft-float implementation. +/* Support for systems that don't have hardware floating-point; there are no flags to + * set, and we don't want to code-gen to an unknown soft-float implementation. + */ double __floatundidf(du_int a) @@ -53,17 +58,18 @@ __floatundidf(du_int a) if (a == 0) return 0.0; const unsigned N = sizeof(du_int) * CHAR_BIT; - int sd = N - __builtin_clzll(a); // number of significant digits - int e = sd - 1; // exponent + int sd = N - __builtin_clzll(a); /* number of significant digits */ + int e = sd - 1; /* exponent */ if (sd > DBL_MANT_DIG) { - // start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx - // finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR - // 12345678901234567890123456 - // 1 = msb 1 bit - // P = bit DBL_MANT_DIG-1 bits to the right of 1 - // Q = bit DBL_MANT_DIG bits to the right of 1 - // R = "or" of all bits to the right of Q + /* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx + * finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR + * 12345678901234567890123456 + * 1 = msb 1 bit + * P = bit DBL_MANT_DIG-1 bits to the right of 1 + * Q = bit DBL_MANT_DIG bits to the right of 1 + * R = "or" of all bits to the right of Q + */ switch (sd) { case DBL_MANT_DIG + 1: @@ -75,27 +81,27 @@ __floatundidf(du_int a) a = (a >> (sd - (DBL_MANT_DIG+2))) | ((a & ((du_int)(-1) >> ((N + DBL_MANT_DIG+2) - sd))) != 0); }; - // finish: - a |= (a & 4) != 0; // Or P into R - ++a; // round - this step may add a significant bit - a >>= 2; // dump Q and R - // a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits + /* finish: */ + a |= (a & 4) != 0; /* Or P into R */ + ++a; /* round - this step may add a significant bit */ + a >>= 2; /* dump Q and R */ + /* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */ if (a & ((du_int)1 << DBL_MANT_DIG)) { a >>= 1; ++e; } - // a is now rounded to DBL_MANT_DIG bits + /* a is now rounded to DBL_MANT_DIG bits */ } else { a <<= (DBL_MANT_DIG - sd); - // a is now rounded to DBL_MANT_DIG bits + /* a is now rounded to DBL_MANT_DIG bits */ } double_bits fb; - fb.u.high = ((e + 1023) << 20) | // exponent - ((su_int)(a >> 32) & 0x000FFFFF); // mantissa-high - fb.u.low = (su_int)a; // mantissa-low + fb.u.high = ((e + 1023) << 20) | /* exponent */ + ((su_int)(a >> 32) & 0x000FFFFF); /* mantissa-high */ + fb.u.low = (su_int)a; /* mantissa-low */ return fb.f; } #endif |