Lynx update including file routines that access a file system on a cartridge

by Karri Kaksonen.


git-svn-id: svn://svn.cc65.org/cc65/trunk@4892 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/lynx/open.s

@@ -0,0 +1,127 @@
+;
+; Karri Kaksonen, 2010
+;
+; This function reads the directory entry for file "name".
+;
+; The name is actually plain ASCII string starting from
+; "0", "1", up to "4095" which is the largest file number we can handle.
+;
+; open() does not take part in what kind of cart we have. If it is RAM
+; you may also be able to write into it. Therefore we allow both reads
+; and writes in this routine.
+;
+; int open(const char *name, int flags, ...)
+;
+; As helper functions we also provide.
+; void openn(int fileno)
+;
+	.importzp	sreg, tmp3
+	.macpack	longbranch
+	.import		_atoi
+	.import		_read
+	.import		_lseek
+	.import		addysp,popax,pushax,decsp6,pusha0,pusheax,ldaxysp
+	.import		aslax3,axlong,tosaddeax,steaxysp,stax0sp,incsp8
+	.import		ldax0sp
+	.importzp	_FileEntry
+	.importzp	_FileStartBlock
+	.importzp	_FileCurrBlock
+	.importzp	_FileBlockOffset
+	.import		__STARTOFDIRECTORY__
+	.export		_open
+	.export		_openn
+
+	.include	"errno.inc"
+	.include	"fcntl.inc"
+
+.segment	"DATA"
+
+_startofdirectory:
+	.dword	__STARTOFDIRECTORY__
+
+; ---------------------------------------------------------------
+; int __near__ open (__near__ const unsigned char*, int)
+; ---------------------------------------------------------------
+
+.segment	"CODE"
+
+.proc	_open
+
+.segment	"CODE"
+
+	dey
+	dey
+	dey
+	dey
+	beq	parmok
+	jsr	addysp
+
+parmok:	jsr	popax
+	sta	tmp3
+	and	#(O_RDWR | O_CREAT)
+	cmp	#O_RDONLY
+	beq	flagsok
+	cmp	#(O_WRONLY | O_CREAT)
+	beq	flagsok
+	lda	#EINVAL
+	ldx	#0
+	jmp	__directerrno
+
+flagsok:
+	jsr	popax
+	jsr     _atoi
+	jsr     pushax
+	jsr     ldax0sp
+	jsr     _openn
+	ldx     #$00
+	lda     #$01
+	stx	__oserror
+	rts
+
+.endproc
+
+; ---------------------------------------------------------------
+; void __near__ __fastcall__ openn (int)
+; ---------------------------------------------------------------
+
+.segment	"CODE"
+
+.proc	_openn: near
+
+.segment	"CODE"
+
+	jsr     pushax
+	jsr     decsp6
+	lda     #$01
+	jsr     pusha0
+	lda     _startofdirectory+3
+	sta     sreg+1
+	lda     _startofdirectory+2
+	sta     sreg
+	ldx     _startofdirectory+1
+	lda     _startofdirectory
+	jsr     pusheax
+	ldy     #$0D
+	jsr     ldaxysp
+	jsr     aslax3
+	jsr     axlong
+	jsr     tosaddeax
+	jsr     pusheax
+	ldx     #$00
+	txa
+	jsr     _lseek
+	ldy     #$02
+	jsr     steaxysp
+	lda     #$01
+	jsr     pusha0
+	lda     _FileEntry
+	ldx     _FileEntry+1
+	jsr     pushax
+	ldx     #$00
+	lda     #$08
+	jsr     _read
+	jsr     stax0sp
+	jmp     incsp8
+
+.endproc
+