math: fix exp.s on i386 and x86_64 so the exception flags are correct

[musl] / src / math / i386 / exp.s

diff --git a/src/math/i386/exp.s b/src/math/i386/exp.s
index 18f6cd6..c7f5ad0 100644 (file)
--- a/src/math/i386/exp.s
+++ b/src/math/i386/exp.s
@@ -1,3 +1,37 @@
+.global expm1f
+.type expm1f,@function
+expm1f:
+       flds 4(%esp)
+       jmp 1f
+
+.global expm1l
+.type expm1l,@function
+expm1l:
+       fldt 4(%esp)
+       jmp 1f
+
+.global expm1
+.type expm1,@function
+expm1:
+       fldl 4(%esp)
+1:     fldl2e
+       fmulp
+       fld1
+       fld %st(1)
+       fabs
+       fucom %st(1)
+       fnstsw %ax
+       fstp %st(0)
+       fstp %st(0)
+       sahf
+       ja 1f
+       f2xm1
+       ret
+1:     call 1f
+       fld1
+       fsubrp
+       ret
+
 .global exp2f
 .type exp2f,@function
 exp2f:
@@ -34,13 +68,49 @@ exp:
 .type exp2,@function
 exp2:
        fldl 4(%esp)
-1:     fld %st(0)
-       frndint
+1:     pushl $0x467ff000
+       flds (%esp)       # 16380
+       xorl %eax,%eax
+       pushl $0x80000000
+       push %eax
+       fld %st(1)
+       fabs
+       fucomp %st(1)
+       fnstsw
+       fstp %st(0)
+       sahf
+       ja 3f             # |x| > 16380
+       jp 2f             # x is nan (avoid invalid except in fistp)
+       fld %st(0)
+       fistpl 8(%esp)
+       fildl 8(%esp)
        fxch %st(1)
        fsub %st(1)
+       mov $0x3fff,%eax
+       add %eax,8(%esp)
        f2xm1
        fld1
-       faddp
-       fscale
+       faddp             # 2^(x-rint(x))
+       fldt (%esp)       # 2^rint(x)
+       fmulp
+       fstp %st(1)
+2:     add $12,%esp
+       ret
+
+3:     fld %st(0)
+       fstpt (%esp)
+       fld1
+       mov 8(%esp),%ax
+       and $0x7fff,%ax
+       cmp $0x7fff,%ax
+       je 1f             # x = +-inf
+       fld %st(1)
+       frndint
+       fxch %st(2)
+       fsub %st(2)       # st(0)=x-rint(x), st(1)=1, st(2)=rint(x)
+       f2xm1
+       faddp             # 2^(x-rint(x))
+1:     fscale
        fstp %st(1)
+       add $12,%esp
        ret