From: Ken Thompson <ken@research.uucp>
Date: Wed, 14 May 1975 00:49:31 +0000 (-0500)
Subject: Research V6 development
X-Git-Tag: Research-V6~225
X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/commitdiff_plain/e91bac6d2dec9c9c318467a2a59be63e07f82946

Research V6 development
Work on file usr/source/s1/dc4.s

Synthesized-from: v6
---

diff --git a/usr/source/s1/dc4.s b/usr/source/s1/dc4.s
new file mode 100644
index 0000000000..cdc6bda408
--- /dev/null
+++ b/usr/source/s1/dc4.s
@@ -0,0 +1,408 @@
+.globl	getchar
+.globl	stats
+.globl	lookchar
+.globl	fsfile
+.globl	seekchar
+.globl	backspace
+.globl	putchar
+.globl	alterchar
+.globl	move
+.globl	rewind
+.globl	create
+.globl	zero
+.globl	allocate
+.globl	release
+.globl	collect
+.globl	getword, putword
+.globl	length, position
+.globl	w, r, a, l
+/
+testing = 0
+/
+/
+/	routine to return the length of a string
+/
+/	mov	...,r1
+/	jsr	pc,length
+/	mov	r0,...
+/
+length:
+	mov	w(r1),r0
+	sub	a(r1),r0
+	rts	pc
+/
+/
+/	routine to return the read pointer position
+/
+/	mov	...,r1
+/	jsr	pc,position
+/	mov	r0,...
+/
+position:
+	mov	r(r1),r0
+	sub	a(r1),r0
+	rts	pc
+/
+/
+/
+/
+/	routine to get a word from the string
+/	mov	...,r1
+/	jsr	pc,getword
+/	mov	r0,...
+/
+getword:
+	jsr	pc,getchar
+	bes	noch
+	movb	r0,nchar
+	jsr	pc,getchar
+	bec	2f
+	dec	r(r1)
+	br	noch
+2:	movb	r0,nchar+1
+	mov	nchar,r0
+	tst	r0		/tst clears c-bit
+	rts	pc
+/
+/
+/	routine to put a word onto the string
+/	mov	...,r1
+/	mov	...,r0
+/	jsr	pc,putword
+/
+putword:
+	jsr	pc,putchar
+	swab	r0
+	jsr	pc,putchar
+	swab	r0
+	rts	pc
+/
+.bss
+nchar:	.=.+2
+.text
+/
+/
+/
+/	routine to read next character from string
+/	pointed to by r1;  character returned in r0
+/	c-bit set if character not available (end of file)
+/	r1 is preserved
+/
+/	mov	...,r1
+/	jsr	pc,getchar
+/	movb	r0,...
+/
+getchar:
+	jsr	pc,lookchar
+	bec	2f
+	rts	pc
+2:	inc	r(r1)
+	tst	r0		/tst clears c-bit
+	rts	pc
+/
+noch:	clr	r0
+	sec
+	rts	pc
+/
+/	routine to look at next character from string
+/	pointed to by r1;  character returned in r0
+/	c-bit set if character not available (end of file)
+/	r1 is preserved
+/
+/	mov	...,r1
+/	jsr	pc,lookchar
+/	movb	r0,...
+/
+lookchar:
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+6.
+	.endif
+	cmp	w(r1),r(r1)
+	blos	noch
+	movb	*r(r1),r0
+	clc
+	rts	pc
+/
+plausible:
+	cmp	r1,$headers
+	bhis 9f; 4; 9:
+	cmp	r1,$headend
+	blo 9f; 4; 9:
+	rts	pc
+/
+/
+/
+/	routine to move the read pointer of a string to a
+/	specified point.  If the string is not long enough,
+/	the string is extended
+/
+/	mov	position,r0
+/	mov	...,r1
+/	jsr	pc,seekchar
+/
+seekchar:
+	mov	r1,-(sp)
+	mov	r0,-(sp)
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+10.
+	.endif
+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,move
+	jsr	pc,swap
+	jsr	pc,release
+	mov	2(sp),r1
+	br	1b
+1:
+	mov	(sp)+,r0
+	mov	(sp)+,r1
+	rts	pc
+/
+/
+/	routine to move read pointer of string to end of string
+/
+/	mov	...,r1
+/	jsr	pc,fsfile
+/
+fsfile:
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+10.
+	.endif
+	mov	w(r1),r(r1)
+	rts	pc
+/
+/
+/	routine to read a string backwards
+/	the read pointer is decremented before reading
+/
+/	mov	...,r1
+/	jsr	pc,backspace
+/	mov	r0,...
+/
+backspace:
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+6.
+	.endif
+	cmp	a(r1),r(r1)
+	bhis	noch
+	dec	r(r1)
+	movb	*r(r1),r0
+	clc
+	rts	pc
+/
+/
+/
+/
+/	routine to put a character into the string
+/	pointed to by r1;  character in r0
+/	r0 and r1 are preserved.
+/
+/	movb	ch,r0
+/	mov	...,r1
+/	jsr	pc,putchar
+/
+putchar:
+	mov	r1,-(sp)
+	mov	r0,-(sp)
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+8.
+	.endif
+1:	cmp	w(r1),l(r1)
+	blt	3f
+	mov	w(r1),r0
+	inc	r0
+	sub	a(r1),r0	/W-A+1
+	jsr	pc,allocate
+	mov	2(sp),r0	/r1
+	jsr	pc,move
+	jsr	pc,swap
+	jsr	pc,release
+	mov	2(sp),r1	/r1
+	cmp	w(r1),l(r1)
+	blt	3f
+	jmp	err
+/
+3:	movb	(sp),*w(r1)
+	inc	w(r1)
+	mov	(sp)+,r0
+	tst	(sp)+
+	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
+/
+/
+/	routine to alter a character in the string
+/	pointed to by r1;  character in r0
+/	r0 and r1 are preserved.
+/
+/	movb	ch,r0
+/	mov	...,r1
+/	jsr	pc,alterchar
+/
+alterchar:
+	mov	r1,-(sp)
+	mov	r0,-(sp)
+	.if	testing
+	jsr	pc,preposterous
+	inc	stats+8.
+	.endif
+1:	cmp	r(r1),l(r1)
+	blt	3f
+	mov	l(r1),r0
+	inc	r0
+	sub	a(r1),r0	/W-A+1
+	jsr	pc,allocate
+	mov	2(sp),r0	/r1
+	jsr	pc,move
+	jsr	pc,swap
+	jsr	pc,release
+	mov	2(sp),r1	/r1
+	cmp	r(r1),l(r1)
+	blt	3f
+	jmp	err
+/
+3:	movb	(sp),*r(r1)
+	inc	r(r1)
+	cmp	r(r1),w(r1)
+	ble	1f
+	mov	r(r1),w(r1)
+1:
+	mov	(sp)+,r0
+	tst	(sp)+
+	rts	pc
+/
+/
+/	routine to move the contents of one string
+/	to another.
+/
+/	mov	source,r0
+/	mov	dest,r1
+/	jsr	pc,move
+/
+/	on return, r1 points to the new string and should
+/	be saved.  r0 is preserved.
+/
+move:
+	mov	r3,-(sp)
+	mov	r2,-(sp)
+	mov	r1,-(sp)
+	mov	r0,-(sp)
+	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
+	mov	r2,r0
+	jsr	pc,allocate
+	mov	2(sp),r0	/r1
+	jsr	pc,swap
+	jsr	pc,release
+	mov	r0,r1
+	mov	0(sp),r0	/r0
+/
+1:	mov	a(r0),(r0)
+	mov	a(r1),(r1)
+1:	dec	r2
+	blt	1f
+	movb	*(r0),*(r1)
+	inc	(r0)
+	inc	(r1)
+	br	1b
+/
+/	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)+,r0
+	mov	(sp)+,r1
+	mov	(sp)+,r2
+	mov	(sp)+,r3
+	rts	pc
+/
+/
+/	routine to rewind read pointer of string
+/	pointed to by r1
+/
+/	mov	...,r1
+/	jsr	pc,rewind
+/
+rewind:
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+10.
+	.endif
+	mov	a(r1),r(r1)
+	rts	pc
+/
+/	routine to rewind write pointer of string
+/	pointed to by r1
+/
+/	mov	...,r1
+/	jsr	pc,create
+/
+create:
+	.if	testing
+	jsr	pc,plausible
+	inc	stats+10.
+	.endif
+	mov	a(r1),w(r1)
+	mov	a(r1),r(r1)
+	rts	pc
+/
+/
+/	routine to zero a string
+/
+/	mov	...,r1
+/	jsr	pc,zero
+/
+zero:
+	mov	r0,-(sp)
+	.if	testing
+	jsr	pc,preposterous
+	.endif
+	mov	a(r1),r0
+1:	cmp	r0,l(r1)
+	bhis	1f
+	clrb	(r0)+
+	br	1b
+1:	mov	(sp)+,r0
+	rts	pc
+/
+/