-.global acosf
-.type acosf,@function
-acosf:
- flds 4(%esp)
- jmp 1f
-
-.global acosl
-.type acosl,@function
-acosl:
- fldt 4(%esp)
- jmp 1f
+# use acos(x) = atan2(fabs(sqrt((1-x)*(1+x))), x)
.global acos
.type acos,@function
acos:
fldl 4(%esp)
-1: fld1
- fld %st(1)
+ fld %st(0)
fld1
- fsubp
- fxch %st(2)
- faddp
- fdivp
+ fsub %st(0),%st(1)
+ fadd %st(2)
+ fmulp
fsqrt
- fld1
+ fabs # fix sign of zero (matters in downward rounding mode)
fxch %st(1)
fpatan
- fld1
- fld1
- faddp
- fmulp
+ fstpl 4(%esp)
+ fldl 4(%esp)
ret