implement line buffered reads, optional with LINEBUF define

git-svn-id: svn://svn.cc65.org/cc65/trunk@3052 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/atari/read.s

@@ -1,5 +1,5 @@
 ;
-; Christian Groessler, Apr-2000
+; Christian Groessler, May-2004
 ;
 ; int __fastcall__ read(int fd,void *buf,int count)
 ;
@@ -12,6 +12,14 @@ _read:	jsr	__rwsetup	; do common setup for read and write
 	beq	done		; if size 0, it's a no-op
 	cpx	#$FF		; invalid iocb?
 	beq	_inviocb
+
+.ifdef	LINEBUF
+	; E: should be always at IOCB #0
+	; fixme: what happens when user closes and reopens stdin?
+	cpx	#0		; E: handler (line oriented keyboard input)?
+	beq	do_line
+.endif
+
 	lda	#GETCHR		; iocb command code
 	sta	ICCOM,x
 	jsr	CIOV		; read it
@@ -24,10 +32,151 @@ done:	lda	ICBLL,x		; buf len lo
 	pha			; save
 	lda	ICBLH,x		; get buf len hi
 	tax			; to X
-	lda	#0
+okdone:	lda	#0
 	sta	__oserror	; clear system dependend error code
 	pla			; get buf len lo
 	rts
 
 _inviocb:
 	jmp	__inviocb
+
+
+.ifdef	LINEBUF
+
+; line oriented input
+
+do_line:
+	lda	buflen		; line buffer active?
+	bne	use_buf		; yes, get data from there
+
+	; save user buffer address & length
+	; update IOCB to point to line buffer
+	lda	ICBLL,x
+	pha
+	lda	#LINEBUF
+	sta	ICBLL,x
+	;--------
+	lda	ICBLH,x
+	pha
+	lda	#0
+	sta	ICBLH,x
+	;--------
+	lda	ICBAL,x
+	pha
+	lda	#<linebuf
+	sta	ICBAL,x
+	;--------
+	lda	ICBAH,x
+	pha
+	lda	#>linebuf
+	sta	ICBAH,x
+
+	lda	#GETREC
+	sta	ICCOM,x
+	jsr	CIOV		; read input data
+	bpl	newbuf
+	cpy	#EOFERR		; eof is treated specially
+	beq	newbuf
+	pla			; fix stack
+	pla
+	pla
+	pla
+	jmp	__do_oserror	; update errno
+
+newbuf:
+	lda	ICBLL,x		; get # of bytes read
+	sta	buflen
+	lda	#0
+	sta	index
+
+	; restore user buffer address & length
+	pla
+	sta	ICBAH,x
+	;--------
+	pla
+	sta	ICBAL,x
+	;--------
+	pla
+	sta	ICBLH,x
+	;--------
+	pla
+	sta	ICBLL,x
+
+	; fall into use_buf
+
+; return bytes from line buffer
+; use buflen and index to access buffer
+; update index
+; use dataptr as a temporary pointer
+
+use_buf:
+	lda	buflen
+	sec
+	sbc	index		; size of unread data in the buffer
+	sta	cbs
+
+	lda	ICBLL,x		; buf len lo
+	cmp	cbs		; larger than buffer size?
+	beq	bl1
+	bcs	btsmall		; yes, adjust length
+
+bl1:	lda	ICBLH,x		; get buf len hi
+	bne	btsmall		; buffer too small: buffer contents < read size
+
+; copy ICBLL,x bytes
+
+icbll_copy:
+
+	lda	ICBAL,x		; buffer address
+	sta	dataptr
+	lda	ICBAH,x		; buffer address
+	sta	dataptr+1
+	lda	ICBLL,x
+	sta	copylen
+	pha			; remember for return value
+	ldy	#0
+	ldx	index
+
+copy:	lda	linebuf,x
+	sta	(dataptr),y
+	iny
+	inx
+	dec	copylen
+	bne	copy
+
+	pla			; length
+	pha			; save length to return at okdone
+
+	clc
+	adc	index
+	sta	index
+	cmp	buflen		; buffer used up?
+	bcc	c1		; not yet
+
+	lda	#0
+	sta	buflen		; indicate empty line buffer
+
+c1:	ldx	#0
+	jmp	okdone		; return to caller
+
+btsmall:
+	lda	cbs
+	sta	ICBLL,x
+	bne	icbll_copy
+
+;	brk			; not reached
+
+	.zeropage
+
+index:	.res	1		; index into line buffer
+buflen:	.res	1		; length of used part of buffer
+cbs:	.res	1		; current buffer size: buflen - index
+dataptr:.res	2		; temp pointer to user buffer
+copylen:.res	1		; temp counter
+
+	.bss
+
+linebuf:.res	LINEBUF		; the line buffer
+
+.endif		; .ifdef LINEBUF
+