Workstate on disk I/O rework
This commit is contained in:
parent
79a86bad49
commit
e26adff688
19
boot/mbr.asm
19
boot/mbr.asm
|
|
@ -1,6 +1,7 @@
|
|||
cpu 8086
|
||||
|
||||
%define seg 0x060
|
||||
%define seg 0
|
||||
%define off 0x700
|
||||
|
||||
org 0x7C00 - (seg << 4)
|
||||
|
||||
|
|
@ -16,24 +17,12 @@ init: cli
|
|||
.retry: mov ax, 0x0208
|
||||
mov cx, 2
|
||||
mov dh, 0
|
||||
mov bx, 0x100
|
||||
mov bx, off
|
||||
|
||||
int 0x13
|
||||
jc .retry
|
||||
|
||||
xor di, di
|
||||
mov ax, 0x18CD
|
||||
stosw
|
||||
int 0x12
|
||||
mov cl, 6
|
||||
shl ax, cl
|
||||
stosw
|
||||
mov al, 2
|
||||
stosb
|
||||
mov ax, 0x18CD
|
||||
stosw
|
||||
|
||||
jmp seg:0x100
|
||||
jmp seg:off
|
||||
|
||||
times (0x1BE - ($-$$)) db 0
|
||||
|
||||
|
|
|
|||
151
src/@rdos.asm
151
src/@rdos.asm
|
|
@ -1,15 +1,15 @@
|
|||
org 0x700
|
||||
cseg equ 0x0
|
||||
jmp init
|
||||
|
||||
%include "bpb.inc"
|
||||
%include "farptr.inc"
|
||||
|
||||
; drive actually selected for I/O
|
||||
dsknum db 0xFF
|
||||
|
||||
dap db 0x10, 0
|
||||
dw 1
|
||||
dapbuf dw dskbuf, 0
|
||||
dskseek dw 0,0,0,0
|
||||
; dflags bitfields
|
||||
DRVLOG equ 0x01 ; bit 0 (1) - drive logged in (see drvnum)
|
||||
DRVRST equ 0x02 ; bit 1 (2) - controller configured
|
||||
DRVEXT equ 0x04 ; bit 2 (4) - EBIOS supported
|
||||
DIRTY equ 0x08 ; bit 3 (8) - dskbuf dirty
|
||||
|
||||
; initial setup for disk i/o
|
||||
; copy previously set DPT to our data area
|
||||
|
|
@ -23,8 +23,6 @@ dinit xor ax, ax
|
|||
mov es, cx
|
||||
mov word [es:4*0x1E], dpt
|
||||
mov word [es:4*0x1E+2], ds
|
||||
; set segment addr in DAP
|
||||
mov [dapbuf+2], cs
|
||||
ret
|
||||
|
||||
align 16
|
||||
|
|
@ -36,6 +34,8 @@ i13isp jmp short int13i
|
|||
iret
|
||||
align 16
|
||||
|
||||
; Entry point when user program calls int13h
|
||||
; TODO: flush buffer and log out drive
|
||||
int13i call int13
|
||||
iret
|
||||
|
||||
|
|
@ -86,7 +86,7 @@ getprm test byte [dskflag], 4
|
|||
; select a drive for io
|
||||
; IN dl drive number
|
||||
; dont do anything if drive already selected
|
||||
select cmp dl, [dsknum]
|
||||
select cmp dl, [drvnum]
|
||||
je logfdd.ret
|
||||
; clear out current contents
|
||||
push dx
|
||||
|
|
@ -140,7 +140,7 @@ loghdd sub dl, 2
|
|||
sbb bx, 0xAA55
|
||||
jnz .chs
|
||||
; enable ebios and assume controller is configured
|
||||
or byte [dskflag], (2+4)
|
||||
or byte [dflags], DRVCTL | DRVEXT
|
||||
; get chs data (needed or we cant load vbr)
|
||||
.chs call getprm
|
||||
; read mbr
|
||||
|
|
@ -181,74 +181,68 @@ logerr stc
|
|||
ret
|
||||
|
||||
; map sector into dskbuf
|
||||
; sector number from partition start
|
||||
; IN dx:ax sector number
|
||||
map add ax, [bpb+BPBHS]
|
||||
add dx, [bpb+BPBHS+2]
|
||||
; absolute sector count
|
||||
; skip doing a read if sector number matches
|
||||
; IN dx:ax sector number
|
||||
mapabs cmp ax, [dskseek]
|
||||
jne l003
|
||||
cmp dx, [dskseek+2]
|
||||
je l002
|
||||
; flush and read other sector
|
||||
l003 push ax
|
||||
; IN dx:ax absolute sector number
|
||||
map cmp ax, [drvseek]
|
||||
jne .do
|
||||
cmp dx, [drvseek+2]
|
||||
jne .do
|
||||
ret
|
||||
; flush previous contents
|
||||
.do push ax
|
||||
push dx
|
||||
call flush
|
||||
pop dx
|
||||
pop ax
|
||||
; store the sector number
|
||||
mov [dskseek], ax
|
||||
mov [dskseek+2], dx
|
||||
jmp _read
|
||||
; set sector number
|
||||
mov [drvseek], ax
|
||||
mov [drvseek+2], dx
|
||||
; issue read cmd
|
||||
mov ch, 2
|
||||
jmp diskio
|
||||
|
||||
; mark dskbuf as containing unwritten changes
|
||||
dirty or byte [cs:dskflag], 1 ; dirty
|
||||
dirty or word [cs:dflags], DIRTY
|
||||
l002 ret
|
||||
|
||||
; flush buffer if dirty
|
||||
flush test byte [cs:dskflag], 1
|
||||
flush test word [cs:dflags], DIRTY
|
||||
jz l002
|
||||
; low level read and write
|
||||
; call again to retry, no input registers
|
||||
; read or write is configured in cx
|
||||
_write mov ch, 3
|
||||
db 0x3D ; cmp ax, imm16: causes next 2 bytes to be skipped
|
||||
_read mov ch, 2
|
||||
mov cl, 1 ; read len
|
||||
; issue write cmd
|
||||
mov ch, 3
|
||||
|
||||
; Do disk I/O
|
||||
; IN ch 2 = read
|
||||
; 3 = write
|
||||
; Sector number is read from [drvseek]
|
||||
diskio mov cl, 1 ; read len
|
||||
; DS := ES := CS
|
||||
mov ax, cs
|
||||
mov ds, ax
|
||||
mov es, ax
|
||||
call rstseg
|
||||
; check if ebios supported
|
||||
test byte [dskflag], 4
|
||||
jz .l00
|
||||
test word [dflags], DRVEXT
|
||||
jz .noext
|
||||
; set up regs for ebios call
|
||||
mov ax, cx
|
||||
or ah, 0x40
|
||||
mov si, dap
|
||||
jmp .do
|
||||
; check if we can skip controller reset
|
||||
.l00 test byte [dskflag], 2
|
||||
jnz .l01
|
||||
.noext test word [dflags], DRVRST
|
||||
jnz .norst
|
||||
; do controller reset
|
||||
mov dl, [biosnum]
|
||||
mov ah, 0
|
||||
call int13
|
||||
or byte [dskflag], 2
|
||||
; put sectors per cylinder into bx
|
||||
.l01 mov ax, [bpb+BPBSPT]
|
||||
mul word [bpb+BPBNOS]
|
||||
mov bx, ax
|
||||
or word [dflags], DRVRST
|
||||
; put linear sector num into dx:ax
|
||||
mov ax, [dskseek]
|
||||
mov dx, [dskseek+2]
|
||||
; dx:ax = linear count, bx = sectors / cylinder
|
||||
div bx
|
||||
.norst mov ax, [drvseek]
|
||||
mov dx, [drvseek+2]
|
||||
; dx:ax = linear count
|
||||
div word [drvspc]
|
||||
; TODO: is it possible to get an overflow here?
|
||||
xchg ax, dx
|
||||
; dx = cylinder, ax = head * spt + sector
|
||||
mov bl, [bpb+BPBSPT]
|
||||
div byte bl
|
||||
div byte [drvspt]
|
||||
; dx = cylinder, al = head, ah = sector
|
||||
xchg dl, dh
|
||||
ror dl, 1
|
||||
|
|
@ -274,34 +268,57 @@ _read mov ch, 2
|
|||
call int13
|
||||
jc .err
|
||||
; clear dirty flag on success
|
||||
and byte [dskflag], 0xFE
|
||||
and word [dflags], ~DIRTY
|
||||
clc
|
||||
ret
|
||||
; assume controller is misconfigured
|
||||
.err and byte [dskflag], 0xFD
|
||||
.err and word [dflags], ~DRVRST
|
||||
; exit with carry flag set
|
||||
stc
|
||||
ret
|
||||
|
||||
init mov ax, 0x0e38
|
||||
int 0x10
|
||||
init mov ax, cs
|
||||
; boot failure if loaded wrong
|
||||
cmp ax, cseg
|
||||
je $+4
|
||||
int 0x18
|
||||
halt hlt
|
||||
jmp halt
|
||||
|
||||
section .bss
|
||||
dap db 0x10, 0
|
||||
dw 1
|
||||
dw dskbuf, cseg
|
||||
drvseek dw 0,0,0,0
|
||||
|
||||
; bios drive we end up using
|
||||
biosnum resb 1
|
||||
|
||||
; bit 0 (1) - dirty flag for dskbuf
|
||||
; bit 0 (1) - drive logged in (see drvnum)
|
||||
; bit 1 (2) - controller configured
|
||||
; bit 2 (4) - EBIOS supported
|
||||
dskflag resb 1
|
||||
; bit 3 (8) - dskbuf dirty
|
||||
dflags dw 0
|
||||
|
||||
dpt resb 11
|
||||
section .bss
|
||||
|
||||
bpb resb BPBSIZ
|
||||
; drive currently logged in
|
||||
drvnum resb 1
|
||||
; number, just for bios
|
||||
biosnum resb 1
|
||||
|
||||
; DPT tables for 4 floppy drives
|
||||
dpt resb 4*14
|
||||
|
||||
; Information for logged in drive
|
||||
drvss resb 1 ; sector size, 2^(7+n) bytes
|
||||
drvcs resb 1 ; cluster size, 2^(7+n) bytes
|
||||
alignb 4
|
||||
drvspt resb 2 ; sectors per track
|
||||
drvspc resb 2 ; sectors per cylinder
|
||||
drvoff resb 4 ; partition offset
|
||||
drvend resb 4 ; first sector after the partition
|
||||
drvfat resb 4 ; offset to fat table
|
||||
drvrd resb 4 ; offset of root directory
|
||||
drvcla resb 4 ; offset to cluster area
|
||||
drvfn resb 2 ; sectors per fat table
|
||||
|
||||
; disk buffer for I/O operations
|
||||
alignb 2
|
||||
dskbuf resb 512
|
||||
dskbuf resb 1024
|
||||
|
|
|
|||
Loading…
Reference in New Issue