ma93n.s

来自「操作系统SunOS 4.1.3版本的源码」· S 代码 · 共 31 行

        .data
|       .asciz  "@(#)ma93n.s 1.1 92/07/30 Copyr 1986 Sun Micro"
        .even
        .text

|       Copyright (c) 1986 by Sun Microsystems, Inc.

#include "fpcrtdefs.h"

|	ma93n_()  returns 1 if 68881 is an A93N, 0 if not
|	tests loge(1+eps) and denorm/norm boundary

RTENTRY(_ma93n_)
	flognd	onepluseps,fp0		| fp0 = loge(1+2**-52) = 2**-52 approx
	fmoves	fp0,d0
	cmpl	#0x25800000,d0
	bnes	2f
	fmoved	justdenorm,fp0
	fmoves	fp0,d0
	cmpl	#0x00800000,d0
	bnes	2f
	moveq	#1,d0
	bras	1f
2:
	clrl	d0
1:
	RET

onepluseps: .long 0x3FF00000,0x00000001	| 1+2^-52
justdenorm: .long 0x380FFFFF,0xFE000000  | Should round to least single normal.