github.com/afumu/libc@v0.0.6/musl/src/math/i386/asin.s (about)

     1  .global asin
     2  .type asin,@function
     3  asin:
     4  	fldl 4(%esp)
     5  	mov 8(%esp),%eax
     6  	add %eax,%eax
     7  	cmp $0x00200000,%eax
     8  	jb 1f
     9  	fld %st(0)
    10  	fld1
    11  	fsub %st(0),%st(1)
    12  	fadd %st(2)
    13  	fmulp
    14  	fsqrt
    15  	fpatan
    16  	fstpl 4(%esp)
    17  	fldl 4(%esp)
    18  	ret
    19  		# subnormal x, return x with underflow
    20  1:	fsts 4(%esp)
    21  	ret