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#include <limits> | |
#include <cstdio> | |
#include <cstring> | |
int main() | |
{ | |
union { | |
unsigned char b[sizeof(double)]; | |
double d; | |
float f; | |
} u; | |
memset(&u, 0, sizeof(u)); | |
u.f = std::numeric_limits<float>::signaling_NaN(); //__builtin_nansf(""); | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
u.f = std::numeric_limits<float>::quiet_NaN(); //__builtin_nanf(""); | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
u.d = std::numeric_limits<double>::signaling_NaN(); //__builtin_nans(""); | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
u.d = std::numeric_limits<double>::quiet_NaN(); //__builtin_nan(""); | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
} |
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$ for CXX in clang++ g++; do for M in 32 64; do $CXX -m$M -o tmp/nan-$CXX$M tmp/nan.cc; echo "*** $CXX $M bits"; tmp/nan-$CXX$M; done; done | |
*** clang++ 32 bits | |
00 00 c0 ff 00 00 00 00 | |
00 00 c0 ff 00 00 00 00 | |
00 00 00 00 00 00 f8 ff | |
00 00 00 00 00 00 f8 ff | |
*** clang++ 64 bits | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f | |
*** g++ 32 bits | |
00 00 e0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 fc 7f | |
00 00 00 00 00 00 f8 7f | |
*** g++ 64 bits | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f |
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#include <limits> | |
#include <cstdio> | |
#include <cstring> | |
int main() | |
{ | |
union { | |
unsigned char b[sizeof(double)]; | |
double d; | |
float f; | |
} u; | |
memset(&u, 0, sizeof(u)); | |
#if defined(USE_BUILTINS) | |
u.f = __builtin_nansf(""); | |
#else | |
u.f = std::numeric_limits<float>::signaling_NaN(); //__builtin_nansf(""); | |
#endif | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
#if defined(USE_BUILTINS) | |
u.f = __builtin_nanf(""); | |
#else | |
u.f = std::numeric_limits<float>::quiet_NaN(); //__builtin_nanf(""); | |
#endif | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
#if defined(USE_BUILTINS) | |
u.d = __builtin_nans(""); | |
#else | |
u.d = std::numeric_limits<double>::signaling_NaN(); //__builtin_nans(""); | |
#endif | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
#if defined(USE_BUILTINS) | |
u.d = __builtin_nan(""); | |
#else | |
u.d = std::numeric_limits<double>::quiet_NaN(); //__builtin_nan(""); | |
#endif | |
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n", | |
u.b[0], u.b[1], u.b[2], u.b[3], | |
u.b[4], u.b[5], u.b[6], u.b[7]); | |
} |
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$ for CXX in clang++ g++; do for M in 32 64; do for D in '' '-DUSE_BUILTINS'; do $CXX -m$M $D -o tmp/snan-$CXX$M tmp/snan.cc; echo "*** $CXX $M bits $D"; tmp/snan-$CXX$M; done; done; done | |
*** clang++ 32 bits | |
00 00 c0 ff 00 00 00 00 | |
00 00 c0 ff 00 00 00 00 | |
00 00 00 00 00 00 f8 ff | |
00 00 00 00 00 00 f8 ff | |
*** clang++ 32 bits -DUSE_BUILTINS | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f | |
*** clang++ 64 bits | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f | |
*** clang++ 64 bits -DUSE_BUILTINS | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f | |
*** g++ 32 bits | |
00 00 e0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 fc 7f | |
00 00 00 00 00 00 f8 7f | |
*** g++ 32 bits -DUSE_BUILTINS | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 fc 7f | |
00 00 00 00 00 00 f8 7f | |
*** g++ 64 bits | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f | |
*** g++ 64 bits -DUSE_BUILTINS | |
00 00 a0 7f 00 00 00 00 | |
00 00 c0 7f 00 00 00 00 | |
00 00 00 00 00 00 f4 7f | |
00 00 00 00 00 00 f8 7f |
That's with clang's current HEAD and gcc 4.6.3, by the way.
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Updated with builtins.
/cc @trevnorris