Put rootdir and cluster access into separate files

com/@rdos.asm

@@ -10,6 +10,8 @@ banner:	db "RDOS KERNEL ", V, 0x0A, 0x0D, '$', 0x1A
 %include "inc/bpb.asm"
 %include "kernel/drive.asm"
 %include "kernel/fcb.asm"
+%include "kernel/rootdir.asm"
+%include "kernel/cluster.asm"
 
 section .text
 
@@ -23,7 +25,12 @@ init:	call rstseg
 	mov dx, testdta
 	call setdta
 	mov dx, testfcb
-	call fndfst
+
+	call open
+
+	int 3
+
+	call read
 
 	int 3
 

kernel/cluster.asm

@@ -0,0 +1,7 @@
+; read/write data from FAT clusters
+; requires defines from fcb.asm
+
+read	mov bp, sp
+	call fcbdrv
+
+	ret

kernel/drive.asm

@@ -199,12 +199,12 @@ maprel	add ax, [bpb+BPBHS]
 	; skip doing a read if sector number matches
 	; IN	dx:ax	sector number
 mapabs	cmp ax, [dskseek]
-	jne read
+	jne dskread
 	cmp dx, [dskseek+2]
-	jne read
+	jne dskread
 	ret
 
-read	push ax
+dskread	push ax
 	push dx
 	call flush
 	pop dx

kernel/fcb.asm

@@ -55,114 +55,3 @@ setdta	mov [cs:dta], dx
 	; OUT	ES:BX	dta ptr
 getdta	les bx, [cs:dta]
 	ret
-
-	; Load root directory entry
-	; IN	ax	number of directory entry
-	; OUT	cs:di	ptr to directory entry
-lddir	push ax
-	push ax
-	call rstseg
-	pop ax
-	mov cl, 4
-	shr ax, cl
-	xor dx, dx
-	; dx:ax = sector number in rootdir
-	; add sizes of FAT tables
-	xor ch, ch
-	mov cl, byte [bpb+BPBFN]
-.loop:	add ax, [bpb+BPBFS]
-	adc dx, 0
-	loop .loop
-	; add reserved sector count
-	add ax, [bpb+BPBRSC]
-	adc dx, 0
-	; fetch sector (relative to partition)
-	call maprel
-	; get di to point to entry
-	pop di
-	mov cl, 5
-	shl di, cl
-	and di, 0x1FF
-	add di, dskbuf
-	ret
-
-	; find first matching file
-	; IN	DS:DX	input fcb
-fndfst	mov bp, sp
-	call fcbdrv
-	; set search state to zero
-	les di, [cs:dta]
-	xor ax, ax
-	mov [es:di+FCBSIZ], ax
-	; find next matching file
-	; state is kept in DTA
-fndnxt	mov bp, sp
-	call fcbdrv
-	; get next direntry to fetch
-	; get number of current entry from DTA
-.loop	les di, [cs:dta]
-	mov ax, [es:di+FCBSIZ]
-	inc word [es:di+FCBSIZ]
-	; bail out if we are at end of dir
-	cmp ax, [bpb+BPBRDE]
-	jnc .err
-	; load entry and first byte
-	push ds
-	push dx
-	call lddir
-	pop dx
-	pop ds
-	; next if hidden, dir or vol label
-	test byte [cs:di+0x0B], 0xDA
-	jnz .loop
-	; bail out if end of dir
-	mov al, [di]
-	cmp al, 0
-	je .err
-	; next if deleted entry
-	cmp al, 0xE5
-	je .loop
-	; DS:SI := FCB+1
-	; ES:DI := CS:dirent
-	mov si, dx
-	push si
-	inc si
-	mov ax, cs
-	mov es, ax
-	; compare and ; try next if mismatch
-	mov cx, 11
-	push di
-	rep cmpsb
-	pop di
-	pop si
-	jne .loop
-	; create FCB in DTA
-	call getdta
-	xchg bx, di
-	; copy over drive byte
-	movsb
-	; copy filename
-	push ds
-	mov ax, cs
-	mov ds, ax
-	mov si, bx
-	mov cx, 11
-	rep movsb
-	pop ds
-	; done!
-	xor ax, ax
-	ret
-
-.err:	stc
-.ret:	sbb al, al
-	ret
-
-open	call fndfst
-	test al, al
-	jnz .ret
-	; read start cluster
-	mov ax, [cs:bx+26]
-	mov [ds:bx+FCBCLUS], ax
-	; reset record number
-	mov byte [ds:bx+FCBRN], 0
-.ret	ret

kernel/rootdir.asm

@@ -0,0 +1,110 @@
+	; Load root directory entry into buffer
+	; IN	ax	number of directory entry
+	; OUT	cs:di	ptr to directory entry
+lddir	push ax
+	push ax
+	call rstseg
+	pop ax
+	mov cl, 4
+	shr ax, cl
+	xor dx, dx
+	; dx:ax = sector number in rootdir
+	; add sizes of FAT tables
+	xor ch, ch
+	mov cl, byte [bpb+BPBFN]
+.loop:	add ax, [bpb+BPBFS]
+	adc dx, 0
+	loop .loop
+	; add reserved sector count
+	add ax, [bpb+BPBRSC]
+	adc dx, 0
+	; fetch sector (relative to partition)
+	call maprel
+	; get di to point to entry
+	pop di
+	mov cl, 5
+	shl di, cl
+	and di, 0x1FF
+	add di, dskbuf
+	ret
+
+	; find first matching file
+	; IN	DS:DX	input fcb
+fndfst	mov bp, sp
+	call fcbdrv
+	; set search state to zero
+	les di, [cs:dta]
+	xor ax, ax
+	mov [es:di+FCBSIZ], ax
+	; find next matching file
+	; state is kept in DTA
+fndnxt	mov bp, sp
+	call fcbdrv
+	; get next direntry to fetch
+	; get number of current entry from DTA
+.loop	les di, [cs:dta]
+	mov ax, [es:di+FCBSIZ]
+	inc word [es:di+FCBSIZ]
+	; bail out if we are at end of dir
+	cmp ax, [bpb+BPBRDE]
+	jnc .err
+	; load entry and first byte
+	push ds
+	push dx
+	call lddir
+	pop dx
+	pop ds
+	; next if hidden, dir or vol label
+	test byte [cs:di+0x0B], 0xDA
+	jnz .loop
+	; bail out if end of dir
+	mov al, [di]
+	cmp al, 0
+	je .err
+	; next if deleted entry
+	cmp al, 0xE5
+	je .loop
+	; DS:SI := FCB+1
+	; ES:DI := CS:dirent
+	mov si, dx
+	push si
+	inc si
+	mov ax, cs
+	mov es, ax
+	; compare and ; try next if mismatch
+	mov cx, 11
+	push di
+	rep cmpsb
+	pop di
+	pop si
+	jne .loop
+	; create FCB in DTA
+	call getdta
+	xchg bx, di
+	; copy over drive byte
+	movsb
+	; copy filename
+	push ds
+	mov ax, cs
+	mov ds, ax
+	mov si, bx
+	mov cx, 11
+	rep movsb
+	pop ds
+	; done!
+	xor ax, ax
+	ret
+
+.err:	stc
+.ret:	sbb al, al
+	ret
+
+open	call fndfst
+	test al, al
+	jnz .ret
+	; read start cluster
+	mov ax, [cs:bx+26]
+	mov [ds:bx+FCBCLUS], ax
+	; reset record number
+	mov byte [ds:bx+FCBRN], 0
+.ret	ret