add query_sectorsize: query sector size of disk by reading sector #4

and making a status command ($53) to the drive: initial check-in,
needs cleanup


git-svn-id: svn://svn.cc65.org/cc65/trunk@3394 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/atari/diopncls.s

@@ -1,11 +1,12 @@
 ;
-; Christian Groessler, October 2000
+; Christian Groessler, February 2005
 ;
-; This file provides the __dio_open and __dio_close functions
+; This file provides the _dio_open and _dio_close functions
 ; Since on the Atari no real open and close is necessary, they
-; do not much. The __dio_open sets the sector size of the
+; do not open or close something. The _dio_open sets the sector
-; drive which is later used by the _dio_read and _dio_write
+; size of the drive which is later used by the _dio_read and
-; functions.
+; _dio_write functions. To query the sector size, the _dio_open
+; accesses the disk drive.
 ;
 ; dhandle_t	__fastcall__ dio_open  (driveid_t drive_id);
 ; unsigned char __fastcall__ dio_close (dhandle_t handle);
@@ -13,8 +14,9 @@
 
 	.export		_dio_open, _dio_close
 	.export		sectsizetab
-	.import		__oserror
+	.import		__oserror, __sio_call, _dio_read
-	.importzp	ptr1,tmp1
+	.import		pushax, addysp, subysp
+	.importzp	ptr2, tmp1, sp
 	.include	"atari.inc"
 
 
@@ -34,7 +36,7 @@ sectsizetab:
 	asl	a		; make index from drive id
 	asl	a
 	tax
-	lda	#128		; currently hardcoded (until I get an 815 :-)
+	lda	#128		; preset sectsize, will be overridden by query_sectorsize
 	sta	sectsizetab+sst_sectsize,x
 	sta	sectsizetab+sst_flag,x		; set flag that drive is "open"
 	lda	#0
@@ -42,8 +44,6 @@ sectsizetab:
 	sta	__oserror			; success
 	tya
 	sta	sectsizetab+sst_driveno,x
-;	lda	#SSTIDVAL
-;	sta	sectsizetab+sst_id+1,x
 	stx	tmp1
 	lda	#<sectsizetab
 	clc
@@ -53,7 +53,8 @@ sectsizetab:
 	adc	#0
 	tax
 	lda	tmp1
-	rts
+	jmp	query_sectorsize		; query drive for current sector size
+;	rts
 
 _inv_drive:
 	lda	#NONDEV		; non-existent device
@@ -66,14 +67,111 @@ _inv_drive:
 
 .proc	_dio_close
 
-	sta	ptr1
+	sta	ptr2
-	stx	ptr1+1
+	stx	ptr2+1
 	lda	#0
 	ldy	#sst_flag
-	sta	(ptr1),y
+	sta	(ptr2),y
 	sta	__oserror	; success
 	tax
 	rts			; return no error
 
 .endproc
 
+; query drive for current sector size
+; procedure:
+;   - read sector #4 (SIO command $54) to update drive status
+;     read length is 128 bytes, buffer is below the stack pointer,
+;	   sector data is ignored
+;     command status is ignored, we will get an error with a DD disk
+;	   anyway (read size 128 vs. sector size 256)
+;   - issue SIO command $53 (get status) to retrieve the sector size
+;     if the command returns with an error, we set sector size to 128
+;	   bytes
+;
+; AX - handle
+;
+.proc	query_sectorsize
+
+	sta	ptr2
+	stx	ptr2+1		; remember pointer to sectsizetab entry
+
+;	jsr	pushax		; handle for subsequent __sio_call
+
+	ldy	#128
+	jsr	subysp		; use buffer on the stack
+
+	lda	sp
+	pha
+	lda	sp+1
+	pha
+
+	lda	ptr2
+	ldx	ptr2+1
+
+	jsr	pushax		; handle
+	ldx	#0
+	lda	#4
+	jsr	pushax		; sect_num
+
+;	ldy	#128
+;	jsr	subysp		; use buffer on the stack
+;	lda	sp
+;	ldx	sp+1
+	pla
+	tax
+	pla
+;	jsr	pushax		; buffer address (not pushed, _dio_read is __fastcall__)
+
+	jsr	_dio_read	; read sector to update status
+
+	ldy	#128
+	jsr	addysp		; discard stack buffer
+
+
+	lda	ptr2
+	ldx	ptr2+1
+	jsr	pushax		; handle for subsequent __sio_call
+
+
+	ldx	#0
+	lda	#4
+	jsr	pushax		; dummy sector #
+
+	ldx	#>DVSTAT
+	lda	#<DVSTAT
+	jsr	pushax		; buffer address
+
+	ldy	#sst_sectsize
+	lda	#4
+	sta	(ptr2),y	; 4 bytes transfer
+
+	ldx	#%01000000	; direction value
+	lda	#SIO_STAT	; get status
+
+	jsr	__sio_call
+
+	bmi	error
+
+	ldy	#sst_sectsize
+	lda	DVSTAT
+	and	#%100000
+	beq	s128
+
+	lda	#0
+	sta	(ptr2),y
+	iny
+	lda	#1
+;	sta	(ptr2),y
+;	bne	fini2
+
+finish:	sta	(ptr2),y	; set default sector size	
+fini2:	lda	ptr2
+	ldx	ptr2+1
+	rts
+
+error:	ldy	#sst_sectsize
+s128:	lda	#128
+	bne	finish
+
+.endproc