alloc1.s

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.globl	plausible
.globl	lookchar
.globl	wc
.globl	seekchar
.globl	putchar
.globl	allocate
.globl	release
.globl	stats
.globl	w,r,a,l
.globl	bufchar
.globl	copy
.globl	getbuf
.globl	swap
.globl fixct
/
/	routine to copy the contents of one string
/	to another.
/
/	mov	source,r0
/	mov	dest,r1
/	jsr	pc,copy
/	mov	r1,...
/
/	on return, r1 points to the new string and should
/	be saved.  r0 is preserved.
/
copy:
	mov	r0,-(sp)
	mov	r2,-(sp)
	mov	r3,-(sp)
	jsr	pc,wc
1:	jsr	pc,reset
	mov	w(r0),r2
	sub	a(r0),r2	/W-A
	mov	l(r1),r3
	sub	a(r1),r3	/L-A
	cmp	r2,r3
	ble	1f
	jsr	pc,release
	mov	r2,r0
	jsr	pc,allocate
	mov	4(sp),r0
/
1:	mov	a(r1),w(r1)	/rewind w pointer
	mov	a(r0),-(sp)
/
4:	mov	(sp),0f
	mov	afi,r0
	sys	seek;0:.. ;0	/set input pointer
	cmp	r2,$512.
	ble	2f
	mov	$512.,r3	/# output this time
	mov	r3,0f
	mov	r3,3f
	add	r3,(sp)
	sub	r3,r2	/# left to output
	br	1f
/
2:	mov	r2,0f
	mov	r2,3f
	mov	r2,r3
	clr	r2
/
1:	mov	afi,r0
	sys	read;b1;0:..
	bes	bad
	cmp	r0,r3
	bne	bad
	mov	afout,r0
	mov	(r1),0f
	add	r3,(r1)
	sys	seek;0:.. ;0
	sys	write;b1;3:..
	bes	bad
	tst	r2
	bgt	4b
	tst	(sp)+
	mov	4(sp),r0	/restore r0
/
/	fix up read ptr of new string
/
1:	mov	r(r0),r2
	sub	a(r0),r2
	add	a(r1),r2
	mov	r2,r(r1)
/
/	restore and return
/
	mov	(sp)+,r3
	mov	(sp)+,r2
	mov	(sp)+,r0
	rts	pc
/
bad:	mov	$1,r0
	sys write;1f;2f-1f
	4
1:	<error on copy\n>
2:	.even
/
/
wc:
	mov	r1,-(sp)
	mov	r2,-(sp)
	mov	r3,-(sp)
	clr	r3
1:
	cmp	r3,nbuf
	bge	1f
	mov	r3,r2
	asl	r2
	tst	w1(r2)
	ble	2f
	mov	r3,r1
	ashc	$9.,r1
	bic	$777,r1
	add	$b1,r1
	jsr	pc,clean
2:
	inc	r3
	br	1b
1:
	jsr	pc,whead
	mov	(sp)+,r3
	mov	(sp)+,r2
	mov	(sp)+,r1
	rts	pc
swap:
	mov	w(r1),-(sp)
	mov	w(r0),w(r1)
	mov	(sp),w(r0)
	mov	r(r1),(sp)

	mov	r(r0),r(r1)
	mov	(sp),r(r0)
	mov	a(r1),(sp)
	mov	a(r0),a(r1)
	mov	(sp),a(r0)
	mov	l(r1),(sp)
	mov	l(r0),l(r1)
	mov	(sp)+,l(r0)
	rts	pc
/
/
/
/
/
/	mov	position,r0
/	mov	...,r1
/	jsr	pc,seekchar
/
seekchar:
	mov	r1,-(sp)
	mov	r0,-(sp)
1:
	mov	(sp),r0
	add	a(r1),r0
	cmp	r0,l(r1)
	bhi	3f
	mov	r0,r(r1)
	cmp	r0,w(r1)
	blo	1f
	mov	r0,w(r1)
	br	1f
3:
	mov	(sp),r0
	jsr	pc,allocate
	mov	2(sp),r0
	jsr	pc,copy
	jsr	pc,swap
	jsr	pc,release
	mov	2(sp),r1
	br	1b
1:
	mov	(sp)+,r0
	mov	(sp)+,r1
	rts	pc
/
reset:
	mov	r3,-(sp)
	mov	r2,-(sp)
	clr	r3
1:
	cmp	r3,nbuf
	bge	1f
	mov	r3,r2
	asl	r2
	mov	$-1.,w1(r2)
	clr	b1s(r2)
	clr	b1e(r2)
	clr	u1(r2)
	inc	r3
	br	1b
1:
	clr	flag
	mov	(sp)+,r2
	mov	(sp)+,r3
	rts	pc
/