76 lines
1.2 KiB
NASM
76 lines
1.2 KiB
NASM
section .text
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; set default drive for current process
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; IN dl drive number
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setdd: push ds
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mov ds, [cs:curpsp]
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mov [PSPDD], dl
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pop ds
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ret
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; get default drive for current process
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; OUT al drive number
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getdd: push ds
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mov ds, [cs:curpsp]
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mov al, [PSPDD]
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pop ds
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ret
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; auto-complete drive field in fcb
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; IN ds:dx far ptr FCB
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; OUT si copy of dx
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fixfcb: mov si, dx
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cmp byte [si], 0
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jne .ret
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call getdd
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inc dl
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mov byte [si], dl
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.ret: mov dx, si
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ret
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; Load root directory entry
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; IN ax number of directory entry
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lddir: push ax
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mov cl, 4
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shr ax, cl
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xor dx, dx
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call maprd
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; get si to point to entry
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pop si
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mov cl, 5
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shl si, cl
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and si, 0x1FF
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add si, dskbuf
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ret
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; find next file
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fnfile: mov ax, [es:bx+FCBDEN]
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inc word [es:bx+FCBDEN]
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; bail out if we are at end of dir
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cmp ax, [bpb+BPBRDE]
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jnc .err
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; load entry and first byte
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push bx
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call lddir
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pop bx
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; next if hidden, dir or vol label
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test byte [si+0x0B], 0xDA
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jnz fnfile
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; bail out if end of dir
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mov al, [si]
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cmp al, 0
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je .err
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; next if deleted entry
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cmp al, 0xE5
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je fnfile
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clc
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ret
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.err: stc
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ret
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; Open file using FCB
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; IN DS:DX far ptr to FCB
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open: call fixfcb
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int 3
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ret
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