diff options
author | Stephen Canon <scanon@apple.com> | 2010-07-02 23:05:46 +0000 |
---|---|---|
committer | Stephen Canon <scanon@apple.com> | 2010-07-02 23:05:46 +0000 |
commit | 09009c50dd7118ed0bdf97e5c37e23c25e443682 (patch) | |
tree | d4dde6d43f2617eb48d874e52407c9652d7bbbb4 /lib/floatsidf.c | |
parent | 0ef6213cf2363ad443b92a2a7396e7c3fb32c630 (diff) |
[unsigned] int -> float soft-float conversions for single- and double-precision
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@107535 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/floatsidf.c')
-rw-r--r-- | lib/floatsidf.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/lib/floatsidf.c b/lib/floatsidf.c new file mode 100644 index 000000000..ebd1a6b60 --- /dev/null +++ b/lib/floatsidf.c @@ -0,0 +1,54 @@ +//===-- lib/floatsidf.c - integer -> double-precision conversion --*- C -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements integer to double-precision conversion for the +// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even +// mode. +// +//===----------------------------------------------------------------------===// + +#define DOUBLE_PRECISION +#include "fp_lib.h" + +fp_t __floatsidf(int a) { + + const int aWidth = sizeof a * CHAR_BIT; + + // Handle zero as a special case to protect clz + if (a == 0) + return fromRep(0); + + // All other cases begin by extracting the sign and absolute value of a + rep_t sign = 0; + if (a < 0) { + sign = signBit; + a = -a; + } + + // Exponent of (fp_t)a is the width of abs(a). + const int exponent = (aWidth - 1) - __builtin_clz(a); + rep_t result; + + // Shift a into the significand field, rounding if it is a right-shift + if (exponent <= significandBits) { + const int shift = significandBits - exponent; + result = (rep_t)a << shift ^ implicitBit; + } else { + const int shift = exponent - significandBits; + result = (rep_t)a >> shift ^ implicitBit; + rep_t round = (rep_t)a << (typeWidth - shift); + if (round > signBit) result++; + if (round == signBit) result += result & 1; + } + + // Insert the exponent + result += (rep_t)(exponent + exponentBias) << significandBits; + // Insert the sign bit and return + return fromRep(result | sign); +} |