Overhauled

1 files changed, 216 insertions, 44 deletions

diff --git a/disk.asm b/disk.asm
index 1843fca..2e001f8 100644
--- a/disk.asm
+++ b/disk.asm
@@ -2,34 +2,130 @@
 %define _DISK_ASM
 
 %include "stdio.asm"
+SECTORS_PER_TRACK equ 12h
 
 disk_info:
 	push bp
 	mov bp, sp
+	pusha
+
+	mov ax, 0
+	mov es, ax
+	mov di, 0
+
+	mov ah, 08h
+	mov si, disk_info_fmt
+	mov dx, [bp + 4]	; load drive number
+				; {diskette=00h..03h, hdd=80h-81h}
+	cmp dx, 80h
+	jge .is_disk
+
+	.is_diskette:
+	mov si, diskette_info_fmt
+
+	.is_disk:
+	int 13h
+	jc .error
+
+	and word [bp + 4], 07fh	; mask off bit 7
+
+	push cx
+	push dx
+	push ax
+	push word [bp + 4]	; drive number
+	push si			; format string
+	call printf
+	add sp, 2 * 5
+
+	jmp .return
+
+	.error:
+		stc
+	.return:
+		popa
+		mov sp, bp
+		pop bp
+		ret
+
+disk_info_ext:
+	push bp
+	mov bp, sp
+	pusha
+
+	sub sp, 2		; bit-field temp storage
 
 	xor dx, dx
 	mov ah, 41h
 	mov bx, 55aah
 	mov dl, [bp + 4]	; drive number {80h..ffh}
 	int 13h
-	jc .return
+	jc .return		; carry is set on failure
+	mov word [bp - 2], cx	; store bit-field
+
+	and dx, 07fh		; mask off bit 7
+
+	xchg ah, al		; extension version
+	and ax, 00ffh		; mask off high byte
 
-	shr ax, 8
-	push dx
 	push cx
 	push ax
-	push disk_info_fmt
+	push dx
+	push disk_info_ext_fmt
 	call printf
-	add sp, 6
+	add sp, 2 * 4
+
+	mov dx, word [bp - 2]	; load bit-field
+	mov cx, 0000h		; set counter
+
+	.do_flag:
+		mov bx, dx	; load BX with bit-field
+		shr bx, cl	; shift bit-field by count
+		and bx, 01h	; Is the bit set?
+		je .no_flag	; non-zero = YES
+
+		push cx		; push count
+		call disk_info_ext_print_flag	; display flag
+		add sp, 2	; clean up
+	.no_flag:
+		inc cx		; next bit
+		cmp cx, 0fh	; 16 bits in bit field
+		jne .do_flag
 .return:
+	add sp, 2
+	popa
 	mov sp, bp
 	pop bp
 	ret
 
+
+disk_info_ext_print_flag:
+	push bp
+	mov bp, sp
+	pusha
+
+	mov cx, [bp + 4]
+
+	imul cx, cx, 2			; compute WORD offset
+	lea bx, [disk_info_ext_table]	; load array address
+	add bx, cx			; compute string pointer offset
+
+	push word [bx]			; load address of string pointer
+	push .fmt			; load format string
+	call printf
+	add sp, 2 * 2
+.return:
+	popa
+	mov sp, bp
+	pop bp
+	ret
+	.fmt db "           - %s", ASCII_LF, 0
+
+
 disk_last_status:
 	push bp
 	mov bp, sp
 
+	clc				; clear carry flag
 					; DL = drive number
 	mov ah, 01h			; BIOS get status of last drive operation
 	int 13h				; BIOS disk service
@@ -129,7 +225,7 @@ disk_convert_status:
 	push ax					; error code
 	push error_msg_disk_status_fmt
 	call printf				; Print error message
-	add sp, 8				; Clean up stack
+	add sp, 2 * 4				; Clean up stack
 
 .return:
 	popa
@@ -138,15 +234,6 @@ disk_convert_status:
 	ret
 
 
-disk_lba_chs:
-	push bp
-	mov bp, sp
-
-	mov ax, word [bp - 2]	; LBA
-
-	mov sp, bp
-	pop bp
-	ret
 
 disk_reset:
 	push bp
@@ -154,10 +241,10 @@ disk_reset:
 	pusha
 
 	mov ah, 00h		; reset disk
-	mov dl, [bp + 4]	; disk number
+	mov dl, byte [bp + 4]	; disk number
 	int 13h			; BIOS disk service
 	jnc .success
-
+	stc
 .success:
 	popa
 	mov sp, bp
@@ -165,27 +252,77 @@ disk_reset:
 	ret
 
 
-disk_read:
+disk_lba_chs:
 	push bp
 	mov bp, sp
-
-	push di
-	mov di, 3		; retry counter
-.readloop:
 	push ax
 	push bx
-	push cx
 	push dx
+	sub sp, 2 * 3		; -2 = HEAD
+				; -4 = TRACK
+				; -6 = SECTOR
 
-				; AL = Sectors to read
-				; ES:BX = Buffer address
-				; CH = Cylinder (10 bits [6 & 7 of CL are MSB])
-				; CL = Sector (5 lower bits)
-				; DH = Head
-				; DL = Drive
-	mov ah, 02h		; BIOS - read disk sectors
-	int 13h			; BIOS disk service
+	mov si, [bp + 4] ; Linear Block Address
+
+	; compute HEAD
+	mov cx, SECTORS_PER_TRACK
+	shl cx, 1			; SPT * 2
+	xor dx, dx			; initialize quotient
+	mov ax, si			; LBA %
+	mov bx, cx			; (SPT * 2)
+	div bx
+
+	mov ax, dx			; use quotient as next dividend
+	xor dx, dx
+	mov bx, SECTORS_PER_TRACK	; / SPT
+	div bx
+	mov [bp - 2], ax		; store HEAD (remainder)
+
+	; compute TRACK
+	xor dx, dx   			; initialize quotient
+	mov ax, si			; LBA %
+	mov bx, cx			; (SPT * 2)
+	div bx
+	mov [bp - 4], ax		; store TRACK (remainder)
+
+	; compute SECTOR
+	xor dx, dx
+	mov ax, si
+	mov bx, SECTORS_PER_TRACK
+	div bx
+	add dx, 1
+	mov [bp - 6], dx		; store SECTOR (quotient)
+
+	pop dx
+	pop bx
+	pop ax
 
+	; assemble return values
+	mov dh, byte [bp - 2]		; load HEAD
+	mov ch, byte [bp - 4]		; load TRACK
+	mov cl, byte [bp - 6]		; load SECTOR
+
+	add sp, 2 * 3
+	mov sp, bp
+	pop bp
+	ret
+
+
+disk_read:
+	push bp
+	mov bp, sp
+
+	mov si, [bp + 4]	; LBA
+
+	push si
+	call disk_lba_chs		; convert LBA to CHS
+	add sp, 2
+
+	mov ah, 02h
+	mov dl, byte [bp + 6]	; drive number
+	mov al, byte [bp + 8]	; number of sectors to read
+	mov bx, [bp + 10]	; data destination address [es:bx]
+	int 13h
 	jnc .success
 
 	call disk_convert_status
@@ -193,19 +330,37 @@ disk_read:
 	push dx
 	call disk_reset
 	add sp, 2
+	stc
+.success:
+	mov sp, bp
+	pop bp
+	ret
 
 
-	pop dx
-	pop cx
-	pop bx
-	pop ax
+disk_write:
+	push bp
+	mov bp, sp
+
+	mov si, [bp + 4]	; LBA
 
+	push si
+	call disk_lba_chs		; convert LBA to CHS
+	add sp, 2
+
+	mov ah, 03h
+	mov dl, byte [bp + 6]	; drive number
+	mov al, byte [bp + 8]	; number of sectors to read
+	mov bx, [bp + 10]	; data destination address [es:bx]
+	int 13h
+	jnc .success
 
-	dec di
-	jnz .readloop
+	call disk_convert_status
 
+	push dx
+	call disk_reset
+	add sp, 2
+	stc
 .success:
-	pop di
 	mov sp, bp
 	pop bp
 	ret
@@ -215,14 +370,31 @@ disk_read:
 align 2
 drive0: dw 0
 
-msg_disk_reset: db "Drive reset successful.", ASCII_CR, 0
-msg_disk_read: db "Sector read successful.", ASCII_CR, 0
+msg_disk_reset: db "Drive reset successful.", ASCII_LF, 0
+msg_disk_read: db "Sector read successful.", ASCII_LF, 0
+
+error_msg_disk_reset: db "Drive reset failed!", ASCII_LF, 0
+error_msg_disk_read: db "Drive read failed!", ASCII_LF, 0
+
+diskette_info_fmt: db 'FDD(%x): status=%x head_max=%x cyl_max=%x', ASCII_LF, 0
+
+disk_info_fmt: db 'HDD(%x): status=%x head_max=%x cyl_max=%x', ASCII_LF, 0
+disk_info_ext_fmt: db 'HDD(%x): IBM/MS INT 13 Extensions v%x [%x]', ASCII_LF, 0
+
+disk_info_ext_flags:
+	.bit_0: db "Extended disk access support", 0
+	.bit_1: db "Removable drive controller support", 0
+	.bit_2: db "Enhanced disk drive support", 0
+	.reserved: db "Reserved", 0
 
-error_msg_disk_reset: db "Drive reset failed!", ASCII_CR, 0
-error_msg_disk_read: db "Drive read failed!", ASCII_CR, 0
+disk_info_ext_table:
+	dw disk_info_ext_flags.bit_0
+	dw disk_info_ext_flags.bit_1
+	dw disk_info_ext_flags.bit_2
+	.reserved: times(15-3) dw disk_info_ext_flags.reserved
+	dw 0000h	; END of disk_info_ext_table
 
-disk_info_fmt: db 'HDD(%c): INT 13h Ext: %x (%x)', ASCII_CR, 0
-error_msg_disk_status_fmt: db 'ERROR %x: Drive %x: %s', ASCII_CR, 0
+error_msg_disk_status_fmt: db 'ERROR %x: Drive %x: %s', ASCII_LF, 0
 error_msg_disk:
 	eds_success: db "Success", 0					; 00h
 	eds_invalid_command: db "Invalid command", 0