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Diffstat (limited to 'contrib/compiler-rt/lib/floatsisf.c')
-rw-r--r-- | contrib/compiler-rt/lib/floatsisf.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/contrib/compiler-rt/lib/floatsisf.c b/contrib/compiler-rt/lib/floatsisf.c new file mode 100644 index 0000000..4a62975 --- /dev/null +++ b/contrib/compiler-rt/lib/floatsisf.c @@ -0,0 +1,54 @@ +//===-- lib/floatsisf.c - integer -> single-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 single-precision conversion for the +// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even +// mode. +// +//===----------------------------------------------------------------------===// + +#define SINGLE_PRECISION +#include "fp_lib.h" + +fp_t __floatsisf(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); +} |