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| author | Szabolcs Nagy <nsz@port70.net> | 2013-08-15 10:56:57 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <nsz@port70.net> | 2013-08-15 10:56:57 +0000 |
| commit | 31c5fb80b9eae86f801be4f46025bc6532a554c5 (patch) | |
| tree | c5d0912699727ebd96bb5194334ee4dd33dc9c5b /src/math/i386/exp.s | |
| parent | 1b3973fb43fbef80dab1dfc9c788783e78ab5043 (diff) | |
| download | musl-31c5fb80b9eae86f801be4f46025bc6532a554c5.tar.gz musl-31c5fb80b9eae86f801be4f46025bc6532a554c5.tar.xz musl-31c5fb80b9eae86f801be4f46025bc6532a554c5.zip | |
math: fix x86 asin, atan, exp, log1p to raise underflow
underflow is raised by an inexact subnormal float store, since subnormal operations are slow, check the underflow flag and skip the store if it's already raised
Diffstat (limited to 'src/math/i386/exp.s')
| -rw-r--r-- | src/math/i386/exp.s | 37 |
1 files changed, 35 insertions, 2 deletions
diff --git a/src/math/i386/exp.s b/src/math/i386/exp.s index e3b42af5..e5f54588 100644 --- a/src/math/i386/exp.s +++ b/src/math/i386/exp.s @@ -2,7 +2,18 @@ .type expm1f,@function expm1f: flds 4(%esp) - jmp 1f + mov 4(%esp),%eax + add %eax,%eax + cmp $0x01000000,%eax + jae 1f + # subnormal x, return x with underflow + fnstsw %ax + and $16,%ax + jnz 2f + fld %st(0) + fmul %st(1) + fstps 4(%esp) +2: ret .global expm1l .type expm1l,@function @@ -14,10 +25,32 @@ expm1l: .type expm1,@function expm1: fldl 4(%esp) + mov 8(%esp),%eax + add %eax,%eax + cmp $0x00200000,%eax + jae 1f + # subnormal x, return x with underflow + fnstsw %ax + and $16,%ax + jnz 2f + fsts 4(%esp) +2: ret 1: fldl2e fmulp + mov $0xc2820000,%eax + push %eax + flds (%esp) + pop %eax + fucomp %st(1) + fnstsw %ax + sahf fld1 - fld %st(1) + jb 1f + # x*log2e < -65, return -1 without underflow + fstp %st(1) + fchs + ret +1: fld %st(1) fabs fucom %st(1) fnstsw %ax |