nero
/
rdos
1
0
Fork 0
Code Pull Requests Releases Activity

Implement file open

This commit is contained in:
Nero 2021-03-19 18:50:50 +00:00
parent f702006582
commit fbab632616
1 changed files with 21 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
kernel/fcb.asm
View File

@ -1,9 +1,15 @@
; FCB layout ; FCB layout
; 1 byte drive (0=default, 1=A:, 2=B:, ...)
; 8.3 filename
; 8.3 filename for rename
FCBSIZ equ 30 struc FCB
FCBDRV resb 1 ; BYTE drive (0=default, 1=A:, 2=B:, ...)
FCBFN resb 11 ; 11 BYTES filename
FCBCLUS resw 1 ; DWORD current cluster
FCBRN resb 1 ; BYTE record in cluster
endstruc
FCBSIZ equ FCB_size
section .data section .data
@ -136,11 +142,13 @@ fndnxt mov bp, sp
; copy over drive byte ; copy over drive byte
movsb movsb
; copy filename ; copy filename
push ds
mov ax, cs mov ax, cs
mov ds, ax mov ds, ax
mov si, bx mov si, bx
mov cx, 11 mov cx, 11
rep movsb rep movsb
pop ds
; done! ; done!
xor ax, ax xor ax, ax
ret ret
@ -149,5 +157,12 @@ fndnxt mov bp, sp
.ret: sbb al, al .ret: sbb al, al
ret ret
open: open call fndfst
ret 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