ex6_1.ibm

汇编编程艺术

#repetitions 2000000
#unravel 100

#code	("ABS:Sequence 1 w/positive value")
%discount
		mov	ax, 1		;Our positive value
%do
		local	ispos

		cmp	ax, 0
		jge	ispos
		neg	ax
ispos:
#endcode

#code	("ABS:Sequence 2 w/positive value")
%discount
		mov	ax, 1		;Our positive value
%do
		local	ispos

		neg	ax
		jns	ispos
		neg	ax
ispos:
#endcode

#code	("ABS:Sequence 3 w/positive value")
%discount
		mov	ax, 1		;Our positive value
%do
		cwd
		xor	ax, dx
		and	dx, 1
		add	ax, dx
#endcode

#code	("ABS:Sequence 1 w/negative value")
%discount
		mov	ax, -1		;Our negative value
%do
		local	ispos

		cmp	ax, 0
		jge	ispos
		neg	ax
ispos:
#endcode

#code	("ABS:Sequence 2 w/negative value")
%discount
		mov	ax, -1		;Our negative value
%do
		local	ispos

		neg	ax
		jns	ispos
		neg	ax
ispos:
#endcode

#code	("ABS:Sequence 3 w/negative value")
%discount
		mov	ax, -1		;Our negative value
%do
		cwd
		xor	ax, dx
		and	dx, 1
		add	ax, dx
#endcode

#end