nulbuf

.PAGE 'NULBUF'
;*********************************
;* NULBUF: SET NULL RECORDS IN   *
;*         ACT-BUF FOR EXTENTION *
;*    VARS:  NR,RS,LX,ACT-BUF    *
;*      IN: NR= LAST RECORD      *
;*          POSITION IN PREVIOUS *
;*          BUFFER.              *
;*     OUT: NR= LAST RECORD      *
;*          POSITION IN BUFFER   *
;*          FOR NEXT NULBUF OR   *
;*          TO SET LSTCHR.       *
;*********************************
;
NULBUF
	JSR SET00       ;SET INDIRECT PTR
	LDY #2
	LDA #0
NB10
	STA (DIRBUF),Y  ;CLEAR BUFFER
	INY
	BNE NB10
;
	JSR ADDNR       ;ADVANCE NR
NB20
	STA NR,X
	TAY
	LDA #$FF
	STA (DIRBUF),Y  ;INIT RECORD W/ CR
	JSR ADDNR
	BCC NB20        ;NOT DONE
;
	BNE NB30
	LDA #0
	STA NR,X
NB30
	RTS
;
; ADD RS & NR, LEAVE IN ACCUM
; C=1: CROSS BUFFER BOUNDARY
;
ADDNR
	LDX LINDX
	LDA NR,X
	SEC
	BEQ AN05
;
	CLC
	ADC RS,X
	BCC AN10
	BNE AN05
	LDA #2
	BIT ER00
	RTS
;
AN05
	ADC #1          ;ADJUST FOR LINK
	SEC
AN10
	RTS
;
;
.END