mirror of
https://github.com/ScrelliCopter/TECHNO.COM.git
synced 2025-02-21 01:59:25 +11:00
297 lines
6.9 KiB
NASM
297 lines
6.9 KiB
NASM
# TECHNO.COM (payload only) Disassembly by a dinosaur 2022, 2024 (original author unknown)
|
|
# Binary MD5: 4CB859537BCD7BFB9FC5BFD6D74F4782
|
|
# SHA256: BA33A41BA51C3D56B27107A94EF7842235B6D80A3A5B8710AEBDD87EB3A1905C
|
|
# Assemble with GAS: as techno.gas.asm -o techno.gas.o
|
|
# ld -Ttext 0x100 techno.gas.o -o techno.elf
|
|
# objcopy -O binary techno.elf techno.com
|
|
|
|
.code16
|
|
.section .text
|
|
# .org 0x100
|
|
|
|
.global start
|
|
start:
|
|
push %cs
|
|
pop %ds
|
|
jmp main
|
|
nop
|
|
|
|
.global exit
|
|
exit:
|
|
call disable_timer2
|
|
mov $0x4C, %ah
|
|
int $0x21
|
|
|
|
# Params: SI=Bigchar Pointer
|
|
# DI=Screen pos
|
|
# AL=Character
|
|
# AH=Cell Attrib
|
|
# Side effects: SI += 7
|
|
.global draw_bigchar
|
|
draw_bigchar:
|
|
push %di
|
|
push %bx
|
|
push %cx
|
|
mov $7, %cx
|
|
next_line: # for (j=0; j<7; ++j):
|
|
push %cx
|
|
push %di
|
|
mov $8, %cx
|
|
mov (%si), %bl # BL = (*SI++)
|
|
inc %si
|
|
cont_line: # for (i=0; i<8; ++i):
|
|
shl $1, %bl # if (0x100 & BL <<= 1):
|
|
jb plot_char
|
|
inc %di
|
|
inc %di
|
|
loop cont_line
|
|
end_line:
|
|
pop %di
|
|
pop %cx
|
|
add $(2 * 80), %di # Next line
|
|
loop next_line
|
|
pop %cx
|
|
pop %bx
|
|
pop %di
|
|
ret
|
|
plot_char: # fn plot_char(AX, DI):
|
|
stosw # ES:[DI] = AX
|
|
loop cont_line
|
|
jmp end_line
|
|
|
|
# Arguments: DX = timer2 frequency
|
|
.global beep
|
|
beep:
|
|
push %ax
|
|
mov $0b10110110, %al # 0 - 16 bit mode
|
|
# 1-3 - Mode 3 (Square wave generator)
|
|
# 4-5 - Access mode: lobyte/hibyte
|
|
# 6-7 - Channel 2
|
|
out %al, $0x43 # Timer 8253-5 control bits
|
|
{load} mov %dl, %al
|
|
out %al, $0x42 # Timer 8253-5 lo byte
|
|
{load} mov %dh, %al
|
|
out %al, $0x42 # Timer 8253-5 hi byte
|
|
in $0x61, %al # Read 8255 port B state
|
|
or $0b00000011, %al # Enable Timer 2 Speaker
|
|
out %al, $0x61 # Write 8255 B state
|
|
pop %ax
|
|
ret
|
|
|
|
.global disable_timer2
|
|
disable_timer2:
|
|
push %ax
|
|
in $0x61, %al
|
|
and $0b11111100, %al
|
|
out %al, $0x61
|
|
pop %ax
|
|
ret
|
|
|
|
# Return: AX = 0040:006C - BIOS Counter
|
|
.global get_counter
|
|
get_counter:
|
|
push %ds
|
|
mov $0x40, %ax # Segment 0040 (BIOS)
|
|
mov %ax, %ds
|
|
mov 0x6C, %ax # AX = 0040:006C - BIOS Counter
|
|
pop %ds
|
|
ret
|
|
|
|
|
|
# Wait for next BIOS counter tick
|
|
.global wait_nexttick
|
|
wait_nexttick:
|
|
push %ax
|
|
push %bx
|
|
call get_counter
|
|
{load} mov %ax, %bx
|
|
busywait:
|
|
call get_counter # AX=BIOS counter
|
|
{load} cmp %ax, %bx
|
|
jz busywait
|
|
pop %bx
|
|
pop %ax
|
|
ret
|
|
|
|
.global main
|
|
main:
|
|
mov $0xF, %ah
|
|
int $0x10 # Get current video mode (AL=mode, BH=curent page)
|
|
{load} mov %al, %bl
|
|
mov $0xB800, %ax # Colour displays have their text buffer at B800:0000
|
|
cmp $0x7, %bl # Check if video mode is monochrome
|
|
jnz not_mda
|
|
mov $0xB000, %ax # Monochrome displays' buffer begins at B000:0000
|
|
not_mda:
|
|
mov %ax, %es # Store video segment in Extra Segment
|
|
mov $0x07DC, %ax # Initial character Light Grey on Black, 0xDC
|
|
mov $0xDFDC, %dx # Dancing cursor character pair, Lower half block, Upper half block
|
|
mov $phrase, %bx
|
|
mov $(80 * 25), %cx
|
|
mov $str_techno, %si # " TECHNO "
|
|
{load} xor %di, %di # DI = 0
|
|
main_loop:
|
|
mov %ax, %es:(%di) # Write cursor character
|
|
test $1, %cl # Skip over on odd cycles
|
|
jnz odd_skip # to run music code at half-speed
|
|
push %dx
|
|
cmpb $0, (%bx) # FZ at the end of the musical phrase
|
|
jnz goto_beep
|
|
push %ax
|
|
push %cx
|
|
mov $freqtbl, %bx
|
|
mov mangler, %ax
|
|
mov $4, %cx
|
|
loop_mangle_freqtbl: # for (int i=0; i<4; ++i):
|
|
xor %ax, (%bx) # Mangle the frequency LUT at the end of every measure
|
|
inc %bx
|
|
inc %bx
|
|
loop loop_mangle_freqtbl
|
|
pop %cx
|
|
pop %ax
|
|
mov $phrase, %bx
|
|
goto_beep:
|
|
push %bx
|
|
mov (%bx), %bl # Fetch current note index
|
|
dec %bl # Phrase uses 1-based indicies because of the 0 terminator
|
|
# So we need to convert it to 0-indexed
|
|
mov $0, %bh # BX &= 0xFF
|
|
shl $1, %bl
|
|
mov freqtbl(%bx), %dx # Store frequency from note index into DX
|
|
call beep # Beep with loaded frequency
|
|
pop %bx
|
|
pop %dx
|
|
inc %bx
|
|
odd_skip:
|
|
call wait_nexttick # Wait for next BIOS counter tick
|
|
lodsb # AL = DS:[SI] (get character)
|
|
cmp $0, %al
|
|
jnz skip_nulterm
|
|
mov $str_techno, %si # Reset string on null terminator
|
|
lodsb
|
|
skip_nulterm:
|
|
stosw # Write string character
|
|
#FIXME: Every GAS seems swap the operands no matter what
|
|
.byte 0x86, 0xD6 # xchg %dh, %dl # Swap cursor half-blocks
|
|
{load} mov %dl, %al
|
|
incw mangler
|
|
push %ax
|
|
check_keyboard:
|
|
mov $1, %ah
|
|
int $0x16 # Check for keypresses (AH=scan code, AL=char, ZF=1 if buffer empty)
|
|
jz no_keyboard_input
|
|
mov $0, %ah
|
|
int $0x16 # Read char from buffer (AH=scan code, AL=char)
|
|
cmp $0x1B, %al
|
|
jnz skip_earlyexit
|
|
incb esc_counter # Exit if escape pressed twice
|
|
cmpb $2, esc_counter
|
|
jnz skip_earlyexit
|
|
jmp exit
|
|
skip_earlyexit:
|
|
cmp $str_notuch, %si # Avoid restarting notouch prompt if already active
|
|
jnb notuch_skip
|
|
mov $str_notuch, %si # " >>Don't touch the keyboard<< "
|
|
notuch_skip:
|
|
jmp check_keyboard
|
|
no_keyboard_input:
|
|
pop %ax
|
|
loop main_loop # Loop over every character on the screen
|
|
call disable_timer2 # Stop beeping
|
|
mov $(8*160+13*2), %di # row=8, col=13
|
|
mov $0x07B0, %ax # FG=Light Grey on Black, Light shade block
|
|
mov $9, %cx
|
|
loop_rows: # for (j=0; j<9; ++j):
|
|
push %cx
|
|
push %di
|
|
mov $53, %cx # for (i=0; i<53; ++i):
|
|
rep stosw # (*ES:DI) = AX; DI += 2
|
|
pop %di
|
|
pop %cx
|
|
add $(80 * 2), %di # row += 1
|
|
loop loop_rows
|
|
mov $(9*160+15*2), %di # row=9, col=15
|
|
mov $0x70, %ah # BG=Either Light Grey or White + Blink depending on video mode
|
|
mov $bigtext, %si
|
|
mov $6, %cx
|
|
mov $(str_techno + 2), %bx # "TECHNO"
|
|
loop_bigchar: # for (i=0; i<6; ++i):
|
|
mov (%bx), %al # Load character into accum low
|
|
inc %bx # Next character
|
|
call draw_bigchar
|
|
add $0x10, %di
|
|
loop loop_bigchar
|
|
mov $20, %cx
|
|
wait_loop:
|
|
call wait_nexttick # Wait for 20 ticks
|
|
loop wait_loop
|
|
mov $0, %ah
|
|
int $0x16 # Wait for keypress
|
|
{load} xor %di, %di # DI = 0
|
|
mov $(80 * 25), %cx
|
|
mov $0x0720, %ax # FG=Light Grey on Black, space
|
|
rep stosw # Clear the whole screen
|
|
jmp exit
|
|
|
|
str_techno: .string " TECHNO "
|
|
str_notuch: .string " \257Don't touch the keyboard\256 "
|
|
|
|
mangler: .word 0x0404
|
|
|
|
freqtbl: .word 5424, 2712, 2416, 2280
|
|
|
|
phrase: .byte 3, 2, 1, 1, 2, 1, 1, 2, 1, 1, 3, 2, 1
|
|
.byte 1, 2, 1, 1, 2, 1, 1, 3, 2, 1, 1, 2, 1
|
|
.byte 1, 2, 1, 1, 3, 4, 1, 4, 1, 4, 1, 4, 0
|
|
|
|
bigtext:
|
|
.byte 0b1111111 # 'T'
|
|
.byte 0b0001000
|
|
.byte 0b0001000
|
|
.byte 0b0001000
|
|
.byte 0b0001000
|
|
.byte 0b0001000
|
|
.byte 0b0001000
|
|
|
|
.byte 0b1111111 # 'E'
|
|
.byte 0b1000000
|
|
.byte 0b1000000
|
|
.byte 0b1111100
|
|
.byte 0b1000000
|
|
.byte 0b1000000
|
|
.byte 0b1111111
|
|
|
|
.byte 0b0111111 # 'C'
|
|
.byte 0b1000000
|
|
.byte 0b1000000
|
|
.byte 0b1000000
|
|
.byte 0b1000000
|
|
.byte 0b1000000
|
|
.byte 0b0111111
|
|
|
|
.byte 0b1000001 # 'H'
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
.byte 0b1111111
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
|
|
.byte 0b1000001 # 'N'
|
|
.byte 0b1100001
|
|
.byte 0b1010001
|
|
.byte 0b1001001
|
|
.byte 0b1000101
|
|
.byte 0b1000011
|
|
.byte 0b1000001
|
|
|
|
.byte 0b0111110 # 'O'
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
.byte 0b1000001
|
|
.byte 0b0111110
|
|
|
|
esc_counter: .byte 0
|