145 lines
2.1 KiB
NASM
145 lines
2.1 KiB
NASM
org 0x100
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jmp init
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fcb1 equ 0x5C
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eof equ 0x1A
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stack equ 0x10 ; stack size
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dumpax push ax
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push cx
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push dx
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mov dx, ax
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call dmpdx0
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mov al, 0x0A
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call dmpdx3
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mov al, 0x0D
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call dmpdx3
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pop dx
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pop cx
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pop ax
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ret
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dmpdx0 mov ah, 0xe
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mov cl, 4
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; this double-call is essentially a 4 times repeating loop
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call dmpdx1
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dmpdx1: call dmpdx2
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dmpdx2: ; grab highest nibble from dx
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mov al, dh
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; remove highest nibble from dx
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shl dx, cl
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; shift away second-highest nibble that we accidentally copied
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shr al, cl
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; map 0-9 to ascii codes for '0' to '9'
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add al, 0x30
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; if result is larger than '9', ...
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cmp al, 0x3a
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jl dmpdx3
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; ... add 7 so we continue at 'A'
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add al, 7
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dmpdx3: int 0x10
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ret
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free dw 0 ; free ram size
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lncnt dw 0 ; line count
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rdptr dw 0xFFFF ; infile blk ptr
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getc mov bx, [rdptr]
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cmp bx, 0x80
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jc l01
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mov ah, 0x14
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mov dx, fcb1
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int 0x21
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cmp al, 1
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je l02
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mov bx, 0
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l01 mov al, [0x80+bx]
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cmp al, eof
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je l02
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cmp al, 0
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je l02
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cmp al, 0x0A
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jne l01b
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inc word [lncnt]
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l01b inc bx
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mov [rdptr], bx
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jmp l03
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l02 mov al, 0x1A
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l03 cmp al, eof
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ret
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newlin mov dl, 0x0A
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mov ah, 2
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int 0x21
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mov dl, 0x0D
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int 0x21
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ret
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error mov dl, [bx]
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mov ah, 2
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int 0x21
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inc bx
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cmp dl, 0x20
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jne error
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mov ax, [lncnt]
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call dumpax
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call newlin
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int 0x20
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e_eof db "EOF "
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e_dup db "DUPSYM "
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tok1:
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s_ws db " " ; also used for tabs
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s_com db ","
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s_obr db "["
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s_cbr db "]"
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s_plu db "+"
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s_min db "-"
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align 2
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tok2:
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reg8 db "AL","CL","DL","BL","AH","CH","DH","BH"
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reg16 db "AX","CX","DX","BX","SP","BP","SI","DI"
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sreg db "ES","CS","SS","DS"
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s_db db "DB"
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s_dw db "DW"
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tok3:
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s_org db "ORG"
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s_equ db "EQU"
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; TODO: parse a line into wordlist of tokens and ptrs to strings
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rline: ret
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; clear symbol table
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main mov byte [init], 0
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call rline
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int 0x20
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align 16
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; stuff behind here gets overwritten
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; by symbol table and program data
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init mov ax, [6]
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mov dx, sp
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sub dx, stack
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cmp ax, dx
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jc il01
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mov ax, dx
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il01 sub ax, init
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shr ax, 1
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and ax, 0xFFF0
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mov [free], ax
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; open input file
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mov ah, 0x0F
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mov dx, fcb1
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int 0x21
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mov bx, e_op
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test al, al
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jnz error
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jmp main
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e_op db "NOFILE "
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