math: move x86_64 exp2l implementation to exp2l.s from expl.s

[musl] / src / math / x86_64 / exp2l.s

diff --git a/src/math/x86_64/exp2l.s b/src/math/x86_64/exp2l.s
index 510c256..1f8ed7b 100644 (file)
--- a/src/math/x86_64/exp2l.s
+++ b/src/math/x86_64/exp2l.s
@@ -1 +1,75 @@
-# see expl.s
+.global expm1l
+.type expm1l,@function
+expm1l:
+       fldt 8(%rsp)
+       fldl2e
+       fmulp
+       fld1
+       fld %st(1)
+       fabs
+       fucom %st(1)
+       fnstsw %ax
+       fstp %st(0)
+       fstp %st(0)
+       sahf
+       ja 1f
+       f2xm1
+       ret
+1:     push %rax
+       call 1f
+       pop %rax
+       fld1
+       fsubrp
+       ret
+
+.global exp2l
+.type exp2l,@function
+exp2l:
+       fldt 8(%rsp)
+1:     mov $0x467ff000,%eax
+       mov %eax,-16(%rsp)
+       mov $0x80000000,%eax
+       mov %eax,-20(%rsp)
+       xor %eax,%eax
+       mov %eax,-24(%rsp)
+       flds -16(%rsp)    # 16380
+       fld %st(1)
+       fabs
+       fucom %st(1)
+       fnstsw
+       fstp %st(0)
+       fstp %st(0)
+       sahf
+       ja 3f             # |x| > 16380
+       jp 2f             # x is nan (avoid invalid except in fistp)
+       fld %st(0)
+       fistpl -16(%rsp)
+       fildl -16(%rsp)
+       fxch %st(1)
+       fsub %st(1)
+       mov $0x3fff,%eax
+       add %eax,-16(%rsp)
+       f2xm1
+       fld1
+       faddp             # 2^(x-rint(x))
+       fldt -24(%rsp)    # 2^rint(x)
+       fmulp
+2:     fstp %st(1)
+       ret
+
+3:     fld %st(0)
+       fstpt -24(%rsp)
+       fld1
+       mov -15(%rsp),%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)
+       ret