kernel: add syscall handling stub
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c0b8c107c4
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576b2c6546
199
src/@rdos.asm
199
src/@rdos.asm
@ -2,15 +2,13 @@
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cseg equ 0x0
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jmp init
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%include "bpb.inc"
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%include "farptr.inc"
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;;; Character I/O
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; dflags bitfields
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DRVLOG equ 0x01 ; bit 0 - drive logged in (see drvnum)
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DRVCTL equ 0x02 ; bit 1 - controller configured
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DRVEXT equ 0x04 ; bit 2 - EBIOS supported
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DIRTY equ 0x08 ; bit 3 - dskbuf dirty
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DRVCHS equ 0x10 ; bit 4 - CHS geometry known
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; direct console I/O
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; IN dl character to output or 0xFF if input
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; OUT al character to read
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conio cmp dl, 0xFF
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je conin
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; raw console output
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; IN dl character
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@ -20,16 +18,6 @@ conout xchg ax, dx
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int 0x10
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ret
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; check if character has characters ready
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; OUT al 0xFF if data, 0 if none
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const mov ah, 1
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int 0x16
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jz .emp
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mov ax, 0xFF
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ret
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.emp mov al, 0
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ret
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; read character from console
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; OUT al character or zero
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conin call const
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@ -39,6 +27,16 @@ conin call const
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int 0x16
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.ret ret
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; check if character has characters ready
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; OUT al 0xFF if data, 0 if none
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const mov ah, 1
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int 0x16
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jz .emp
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mov ax, 0xFF
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ret
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.emp mov al, 0
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ret
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; dummy: write to auxillary dev
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auxout ret
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@ -71,13 +69,6 @@ readc call const
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; IN dl character
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putc jmp conout
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; direct console I/O
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; IN dl character to output or 0xFF if input
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; OUT al character to read
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dcon cmp dl, 0xFF
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je conin
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jmp conout
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; output character string
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; IN ds:dx far ptr to string, '$'-terminated
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puts push si
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@ -147,6 +138,18 @@ gets mov si, dx
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call putc
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ret
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;;; Disk i/o
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%include "bpb.inc"
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%include "farptr.inc"
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; dflags bitfields
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DRVLOG equ 0x01 ; bit 0 - drive logged in (see drvnum)
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DRVCTL equ 0x02 ; bit 1 - controller configured
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DRVEXT equ 0x04 ; bit 2 - EBIOS supported
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DIRTY equ 0x08 ; bit 3 - dskbuf dirty
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DRVCHS equ 0x10 ; bit 4 - CHS geometry known
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align 16
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; IBM Interrupt Sharing Protocol structure
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i13isp jmp short int13i
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@ -436,29 +439,6 @@ diskio mov cl, 1 ; read len
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stc
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ret
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; Get interrupt vector
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; IN al interrupt number
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; OUT es:bx vector
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getint mov bl, al
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mov bh, 0
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; multiply with 4
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add bx, bx
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add bx, bx
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les bx, [cs:bx]
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ret
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; Set interrupt vector
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; IN al interrupt number
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; ds:dx vector
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setint mov bl, al
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mov bh, 0
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; multiply with 4
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add bx, bx
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add bx, bx
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mov [cs:bx], dx
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mov [cs:bx+2], ds
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ret
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init mov ax, cs
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; boot failure if loaded wrong
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cmp ax, cseg
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@ -481,11 +461,130 @@ init mov ax, cs
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mov word [4*0x13], int13i
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mov [4*0x13+2], cs
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mov ax, 0x0e37
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int 0x10
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; install int21h handler
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mov word [4*0x21], int21h
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mov [4*0x21+2], cs
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mov dl, 0x36
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mov ah, 2
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int 0x21
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halt hlt
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jmp halt
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;;; Export functions as syscalls
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; SP, BP, SI, DI and ES must be preserved by kernel code
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; DL, DX or DS:DX is input argument from prog
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; AL, BX or ES:BX is return value to prog
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srb equ 0x8000
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srw equ 0x4000
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; DOS style syscall interface
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int21h push bx
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xor bx, bx
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mov bl, ah
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jmp sysc
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; CP/M-86 style syscall interface
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intE0h push bx
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xor bx, bx
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mov bl, cl
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; bx = syscall number
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; stack must be -> BX IP CS FL
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; for return to prog
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sysc add bx, bx
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mov bx, [cs:bx+stab]
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test bh, srw >> 8 ; fork off bx returns
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jnz .l02
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test bh, srb >> 8 ; fork off al returns
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jnz .l01
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; syscall with no return value
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push dx
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push cx
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push ax
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push ds
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call bx
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pop ds
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pop ax
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pop cx
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pop dx
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pop bx
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iret
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; syscalls returning byte in al
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.l01 push dx
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push cx
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push ds
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and bh, ~(srb >> 8)
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call bx
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pop ds
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pop cx
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pop dx
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pop bx
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iret
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; syscalls returning bx or es:bx
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.l02 add sp, 2 ; discard bx on the stack
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push dx
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push cx
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push ax
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push ds
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and bh, ~(srw >> 8)
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call bx
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pop ds
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pop ax
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pop cx
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pop dx
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ret
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section .rodata
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; syscall table
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stab dw 0 ; 0 reboot
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dw getc + srb ; 1 console input
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dw putc ; 2 console output
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dw auxin ; 3 reader in
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dw auxout + srb ; 4 puncher out
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dw lstout ; 5 lister out
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dw 0 ; 6 direct console i/o
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dw 0 ; 7 read i/o byte
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dw 0 ; 8 get i/o byte
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dw 0 ; 9 string output
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dw 0 ; 10 string input
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dw 0 ; 11 console status
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dw 0 ; 12 get version number
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dw 0 ; 13 reset disks
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dw 0 ; 14 set drive
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dw 0 ; 15 open file
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dw 0 ; 16 close file
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dw 0 ; 17 find first
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dw 0 ; 18 find next
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dw 0 ; 19 delete file
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dw 0 ; 20 sequential read
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dw 0 ; 21 sequential write
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dw 0 ; 22 create file
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dw 0 ; 23 rename file
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dw 0 ; 24 get login vector
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dw 0 ; 25 get drive
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dw 0 ; 26 set dma addr
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dw 0 ; 27 alloc vector
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dw 0 ; 28 set drive r/o
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dw 0 ; 29 get r/o vector
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dw 0 ; 30 file attr
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dw 0 ; 31 get addr of disk parameter block
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dw 0 ; 32 get user number
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dw 0 ; 33 random read
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dw 0 ; 34 random write
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dw 0 ; 35 calculate file size
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dw 0 ; 36 calculate cur record number
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dw 0 ; 37 reset drive
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dw 0 ; 38
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dw 0 ; 39
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dw 0 ; 40 random write with block init
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stab_e nop
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section .data
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dap db 0x10, 0
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dw 1
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dw dskbuf, cseg
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