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| author | Corinna Vinschen <corinna@vinschen.de> | 2016-07-18 22:00:17 +0200 |
|---|---|---|
| committer | Corinna Vinschen <corinna@vinschen.de> | 2016-07-18 22:00:17 +0200 |
| commit | 71df3bfd51cd5ee71f52a85470dc267be05d3f46 (patch) | |
| tree | 74a39f78c08e991bb81b1208bff7b22533b14b98 | |
| parent | 52d940e2633d79eb48982cb76f972f869d770f1a (diff) | |
| download | cygnal-71df3bfd51cd5ee71f52a85470dc267be05d3f46.tar.gz cygnal-71df3bfd51cd5ee71f52a85470dc267be05d3f46.tar.bz2 cygnal-71df3bfd51cd5ee71f52a85470dc267be05d3f46.zip | |
truncl: Fix setting rounding bits in FPU control word
Mingw-w64, which is the source of this code, uses different
definitions of the rounding bits FE_TONEAREST and friends.
They immediately reflect the bit values in the FPU control word,
while on Cygwin they are shifted down to become the values 0-3.
Fix the bit computing expression to account for the difference.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
| -rw-r--r-- | winsup/cygwin/math/truncl.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/winsup/cygwin/math/truncl.c b/winsup/cygwin/math/truncl.c index ddc6af68f..9380f9571 100644 --- a/winsup/cygwin/math/truncl.c +++ b/winsup/cygwin/math/truncl.c @@ -6,6 +6,10 @@ #include <fenv.h> #include <math.h> +/* Mask and shift amount for rounding bits on x86/x86_64. */ +#define FE_CW_ROUND_MASK (0x0c00) +#define FE_CW_ROUND_SHIFT (10) + long double truncl (long double _x) { @@ -16,8 +20,8 @@ truncl (long double _x) unsigned short saved_cw; unsigned short tmp_cw; __asm__ __volatile__ ("fnstcw %0;" : "=m" (saved_cw)); /* save FPU control word */ - tmp_cw = (saved_cw & ~(FE_TONEAREST | FE_DOWNWARD | FE_UPWARD | FE_TOWARDZERO)) - | FE_TOWARDZERO; + tmp_cw = (saved_cw & ~FE_CW_ROUND_MASK) + | (FE_TOWARDZERO << FE_CW_ROUND_SHIFT); __asm__ __volatile__ ("fldcw %0;" : : "m" (tmp_cw)); __asm__ __volatile__ ("frndint;" : "=t" (retval) : "0" (_x)); /* round towards zero */ __asm__ __volatile__ ("fldcw %0;" : : "m" (saved_cw) ); /* restore saved control word */ |