sector reading fixes

src/dos_m65/dev_floppy/dev_fd_cmd_open.s

@@ -6,12 +6,68 @@
 
 dev_fd_cmd_OPEN:
 
-	; XXX provide implementation
+	lda #$01                 ; mode: receive command or file name
+	sta FD_MODE
 
-	jmp dos_EXIT_SEC
+	jmp dos_EXIT_CLC
 
 dev_fd_cmd_OPEN_EOI:
 
+	; XXX this dispatcher is temporary
+
+	; Erase filter pattern     XXX this should be moved to common part
+
+	ldy #$0F
+	lda #$A0
+@lp1:
+	sta PAR_FPATTERN, y
+	dey
+	bpl @lp1
+
+	; XXX add support for second floppy
+
+	lda FD_CMDFN_BUF
+	cmp #'$'
+	beq dev_fd_cmd_OPEN_dir
+
+	; FALLTROUGH
+
+dev_fd_cmd_OPEN_file:
+
 	; XXX provide implementation
 
 	jmp dos_EXIT_CLC
+
+dev_fd_cmd_OPEN_dir:
+
+	lda #$02                 ; mode: read directory
+	sta FD_MODE
+
+	; Copy the filter from command     XXX this should be moved to common part and deduplicated with file opening
+
+	ldy #$00
+@lp1:
+	lda FD_CMDFN_BUF+1, y
+	cmp #$A0
+	beq @lp1_end
+	sta PAR_FPATTERN, y
+	iny
+	cpy #$10
+	bne @lp1
+
+@lp1_end:
+
+	; XXX experimental code below
+
+	; Try to read track 40, sector 0 (disk header)
+
+	lda #40
+	sta PAR_TRACK
+	lda #$00
+	sta PAR_SECTOR
+
+	jsr dev_fd_util_readsector
+
+	; XXX continue implementation
+
+	jmp dos_EXIT_CLC