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Copy pathsuperboot.asm
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252 lines (212 loc) · 2.77 KB
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Copy pathsuperboot.asm
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252 lines (212 loc) · 2.77 KB
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[BITS 16]
[ORG 0x7C00]
start:
xor ax, ax
mov ds, ax
mov es, ax
mov ss, ax
mov sp, 0x7C00
cld
main_loop:
mov si, prompt
call print_string
mov di, 0x7E00
mov cx, 0
read_loop:
mov ah, 0x00
int 0x16
cmp al, 0x0D
je parse_command
cmp al, 0x08
je handle_backspace
cmp cx, 32
je read_loop
stosb
inc cx
mov ah, 0x0E
int 0x10
sti
hlt
jmp read_loop
handle_backspace:
cmp cx, 0
je read_loop
dec di
dec cx
mov ah, 0x0E
mov al, 0x08
int 0x10
mov al, ' '
int 0x10
mov al, 0x08
int 0x10
jmp read_loop
parse_command:
mov al, 0
stosb
call print_newline
cmp byte [0x7E00], 0
je main_loop
mov si, cmd_help
mov di, 0x7E00
call strcmp
jc do_help
mov si, cmd_cls
mov di, 0x7E00
call strcmp
jc do_cls
mov si, cmd_echo
mov di, 0x7E00
call strcmp
jc do_echo
mov si, cmd_poke
mov di, 0x7E00
call strcmp
jc do_poke
mov si, cmd_peek
mov di, 0x7E00
call strcmp
jc do_peek
mov si, cmd_go
mov di, 0x7E00
call strcmp
jc do_go
mov si, msg_bad
call print_string
jmp main_loop
do_help:
mov si, msg_help
call print_string
jmp main_loop
do_cls:
mov ax, 0x0003
int 0x10
jmp main_loop
do_echo:
mov si, 0x7E05
call print_string
call print_newline
jmp main_loop
do_poke:
mov si, 0x7E05
call parse_hex
push bx
call parse_hex
pop ax
mov [bx], al
jmp main_loop
do_peek:
mov si, 0x7E05
call parse_hex
mov cx, bx
call parse_hex
xor dl, dl
.loop:
cmp dl, 0x0F
jle .continue_line
call print_newline
xor dl, dl
.continue_line:
call hex2ascii
inc bx
mov ax, 0x0E20
int 0x10
inc dl
loop .loop
call print_newline
jmp main_loop
do_go:
mov si, 0x7E03
call parse_hex
call bx
jmp main_loop
hex2ascii:
mov al, [bx]
shr al, 4
call convert
mov al, [bx]
and al, 0x0F
call convert
ret
convert:
cmp al, 0x0A
jl .is_digit
add al, 0x07
.is_digit:
add al, 0x30
mov ah, 0x0E
int 0x10
ret
strcmp:
push di
.loop:
mov al, [si]
cmp al, 0
je .check_delimiter
mov bl, [di]
cmp al, bl
jne .nomatch
inc si
inc di
jmp .loop
.check_delimiter:
mov bl, [di]
cmp bl, ' '
je .match
cmp bl, 0
je .match
.match:
pop di
stc
ret
.nomatch:
pop di
clc
ret
parse_hex:
xor bx, bx
.loop:
lodsb
cmp al, 0
je .done
cmp al, ' '
je .done
mov ah, al
and al, 0x0F
and ah, 0x40
je .store_nibble
add al, 9
.store_nibble:
shl bx, 4
or bl, al
jmp .loop
.done:
ret
print_newline:
mov ah, 0x0E
mov al, 0x0D
int 0x10
mov al, 0x0A
int 0x10
ret
print_string:
mov ah, 0x0E
.loop:
lodsb
cmp al, 0
je .done
int 0x10
jmp .loop
.done:
ret
prompt db 'BMS>', 0
cmd_help db 'help', 0
cmd_cls db 'cls', 0
cmd_echo db 'echo', 0
cmd_poke db 'poke', 0
cmd_peek db 'peek', 0
cmd_go db 'go', 0
msg_help db 'help/cls/echo txt/poke data addr/peek # addr/go addr', 13, 10, 0
msg_bad db '?', 13, 10, 0
times 510-($-$$) db 0
dw 0xAA55