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| author | Szabolcs Nagy <nsz@port70.net> | 2013-08-15 10:54:56 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <nsz@port70.net> | 2013-08-15 10:54:56 +0000 |
| commit | 1b3973fb43fbef80dab1dfc9c788783e78ab5043 (patch) | |
| tree | 5c5355c3b96ef9313343eddf2b69674ea78ba518 /src/math/x86_64/expl.s | |
| parent | c599f4f4d705ba215a2672b92baa1c29d9dd0735 (diff) | |
| download | musl-1b3973fb43fbef80dab1dfc9c788783e78ab5043.tar.gz musl-1b3973fb43fbef80dab1dfc9c788783e78ab5043.tar.xz musl-1b3973fb43fbef80dab1dfc9c788783e78ab5043.zip | |
math: fix x86 expl.s to raise underflow and clean up special case handling
Diffstat (limited to 'src/math/x86_64/expl.s')
| -rw-r--r-- | src/math/x86_64/expl.s | 37 |
1 files changed, 15 insertions, 22 deletions
diff --git a/src/math/x86_64/expl.s b/src/math/x86_64/expl.s index 6d5c1ceb..107f3f52 100644 --- a/src/math/x86_64/expl.s +++ b/src/math/x86_64/expl.s @@ -8,32 +8,25 @@ expl: fldt 8(%rsp) - # special cases: 2*x is +-inf, nan or |x| < 0x1p-32 - # check (exponent|0x8000)+2 < 0xbfff+2-32 - movw 16(%rsp), %ax - movw %ax, %dx - orw $0x8000, %dx - addw $2, %dx - cmpw $0xbfff-30, %dx - jnb 3f - cmpw $1, %dx - jbe 1f - # if |x|<0x1p-32 return 1+x + # interesting case: 0x1p-32 <= |x| < 16384 + # check if (exponent|0x8000) is in [0xbfff-32, 0xbfff+13] + mov 16(%rsp), %ax + or $0x8000, %ax + sub $0xbfdf, %ax + cmp $45, %ax + jbe 2f + test %ax, %ax fld1 - jmp 2f -1: testw %ax, %ax - jns 1f - # if 2*x == -inf,-nan return -0/x - fldz - fchs - fdivp + js 1f + # if |x|>=0x1p14 or nan return 2^trunc(x) + fscale + fstp %st(1) ret - # if 2*x == inf,nan return 2*x -1: fld %st(0) -2: faddp + # if |x|<0x1p-32 return 1+x +1: faddp ret - # should be 0x1.71547652b82fe178p0 == 0x3fff b8aa3b29 5c17f0bc + # should be 0x1.71547652b82fe178p0L == 0x3fff b8aa3b29 5c17f0bc # it will be wrong on non-nearest rounding mode 3: fldl2e subq $48, %rsp |