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Improve error handling in fat bs

This commit is contained in:
Nero 2020-03-02 22:15:46 +00:00
parent 59dd979feb
commit 5eedddd0c9
1 changed files with 15 additions and 1 deletions
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16
fat.asm
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@ -234,12 +234,17 @@ fopen:
fread: push ax fread: push ax
push cx push cx
push dx push dx
; abort if there is no file opened
cmp word [cs:cclus], 0 cmp word [cs:cclus], 0
je .err je .err
; get start sector for data area
call clusec call clusec
push ax push ax
; get current cluster number
mov ax, [cs:cclus] mov ax, [cs:cclus]
; clusters are 2-indexed
sub ax, 2 sub ax, 2
; multiply that with sectors per cluster
mov cl, [cs:fdc.sc] mov cl, [cs:fdc.sc]
xor ch, ch xor ch, ch
mul word cx mul word cx
@ -251,13 +256,22 @@ fread: push ax
; dx:ax now point to the sector that should be read next ; dx:ax now point to the sector that should be read next
call seek call seek
call read call read
jc .err
inc word [cs:csec]
jmp .ret jmp .ret
.err: stc .err: ; in case of error, trash current state
call fclose
stc
.ret: pop dx .ret: pop dx
pop cx pop cx
pop ax pop ax
ret ret
; Reset open file info
fclose: mov [cclus], bx
mov word [csec], 0
ret
main: mov [seek.dl], dl ; save drive number main: mov [seek.dl], dl ; save drive number
call fopen call fopen