1 files changed, 65 insertions, 23 deletions

diff --git a/src/stage1_functions.asm b/src/stage1_functions.asm
index c9ed1a5..8a73a9b 100644
--- a/src/stage1_functions.asm
+++ b/src/stage1_functions.asm
@@ -4,20 +4,6 @@
 ; subtract 1 here!)
 NOF_LOAD_SECTORS equ 38
 
-; IN bx: begin of memory area to dump
-; IN ax: number of words to dump
-dump_range:
-	mov dx, bx
-	call print_hex
-	mov dx, [bx]
-	call print_hex
-	call print_newline
-	add bx, 2
-	dec ax
-	cmp ax, 0
-	jnz dump_range
-	ret
-
 ; IN dx: hex value to print	
 print_hex:
 	push bx
@@ -104,25 +90,76 @@ current_row:
 	pop ax
 	ret
 
+; data sections used for reading from disk
+SECTORS_TO_LOAD:
+	db NOF_LOAD_SECTORS		; load NOF_LOAD_SECTORS sectors in total
+CURRENT_SECTOR:
+	db 2				; second sector after boot sector
+CURRENT_CYLINDER:
+	db 0
+CURRENT_HEAD:
+	db 0				
+
+; read the whole stage2 and kernel from the disk
 ; IN dl: drive to read from
 read_from_disk:
-	mov ah, 0x02			; read sectors from drive
-	
-	mov al, NOF_LOAD_SECTORS	; read 1 sector
-	mov ch, 0			; select first cylinder
-	mov dh, 0			; first head
-	mov cl, 2			; second sector after boot sector
-	
+
 	mov bx, 0			; where to store the data
 	mov es, bx
 	mov bx, 0x7e00			; 512 bytes after first sector
-		
+
+.read_next_sector:
+
+	call read_one_sector_from_disk
+
+	sub [SECTORS_TO_LOAD], BYTE 1	; one less to load
+	cmp [SECTORS_TO_LOAD], BYTE 0	; finished?
+	je .finished
+
+	add bx, 0x200			; advance write buffer position
+	add [CURRENT_SECTOR], BYTE 1	; next sector
+	cmp [CURRENT_SECTOR], BYTE 0x13	; assuming 18 sectors per track for now
+	je .next_head
+	jmp .read_next_sector
+
+.next_head:
+	mov [CURRENT_SECTOR], BYTE 1	; start from first sector again
+	add [CURRENT_HEAD], BYTE 1	; advance head
+	cmp [CURRENT_HEAD], BYTE 0x02	; 2 heads on floppies
+	je .next_track
+	jmp .read_next_sector
+	
+.next_track:
+	mov [CURRENT_HEAD], BYTE 0	; start from head 0 again
+	add [CURRENT_CYLINDER], BYTE 1	; advance track
+	jmp .read_next_sector
+
+.finished:
+	ret
+
+; Read one sector after the other, if we get illegal parameter
+; errors we assume we have gone over the limit of number of
+; sectors per cylinder. This avoids to probe for this number with
+; shacky BIOS functions or with probing (as LILO does). It's not
+; very efficient though..
+; IN dl: drive to read from
+read_one_sector_from_disk:
+	mov ah, 0x02			; read sectors from drive
+	
+	mov al, 1			; read 1 sector
+	mov ch, BYTE [CURRENT_CYLINDER]
+	mov dh, BYTE [CURRENT_HEAD]
+	mov cl, BYTE [CURRENT_SECTOR]
+			
 	int 0x13
 	
 	jc .read_error
 	
-	cmp al, NOF_LOAD_SECTORS	; 1 sector read?
+	cmp al, 1			; 1 sector read?
 	jne .short_read			; if not, short read
+
+	mov al, '.'
+	call print_char
 	
 	ret
 	
@@ -139,3 +176,8 @@ read_from_disk:
 	call print_string
 	jmp $
 
+kill_motor:
+	mov	dx, 0x3F2
+	mov	al, 0x00
+	out	dx, al
+        ret