174 lines
2.6 KiB
Plaintext
174 lines
2.6 KiB
Plaintext
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const fl_zero 0x1
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const fl_eq 0x2
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const fl_be 0x4
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const fl_lt 0x8
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const fl_err 0xa
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const vcd_base 0x2000
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const kbd_status 0x1ffc
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const kbd_code 0x1ffe
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const kbd_flag_is_release 0x1
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const counter 0x600
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_start:
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mov rsp, 0x1000
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mov rbp, rsp
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mov r0, 512
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mov r1, 1
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dskr r0, r1
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; setup video character display (VCD)
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; descriptor table structure:
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; [addr + 0] memory map base
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mov r0, vcd_base
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mov [0x700], r0
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lvcd 0x700
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; setup keyboard (KBD)
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; descriptor table structure:
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; [addr + 0] status address
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; [addr + 2] keycode address
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; [addr + 4] keyboard interrupt handler
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mov r0, kbd_status
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mov [0x702], r0
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mov r0, kbd_code
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mov [0x704], r0
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mov r0, key_press_int
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mov [0x706], r0
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lkbd 0x702
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; character counter
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mov r0, 0
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mov [counter], r0
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main_loop:
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hlt
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jmp main_loop
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key_press_int:
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mov r0, [kbd_status]
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and r0, kbd_flag_is_release
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jnz r0, .leave
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mov r0, [counter]
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add r0, vcd_base
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mov r1, [kbd_code]
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cmp r1, 44 ; spacebar
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mov r2, rfl
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and r2, fl_eq
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jnz r2, .print_space
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add r1, 61 ; scancode letter -> ascii
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mov [rsp], r1
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add rsp, 2
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call print_u16
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sub rsp, 2
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jmp .leave
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.print_space:
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mov r1, ' '
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mov [rsp], r1
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add rsp, 2
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call term_putc
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sub rsp, 2
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.leave:
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reti
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const term_width 20
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term_y:
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dw 0
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term_x:
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dw 0
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term_putc:
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mov [rsp], rbp
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add rsp, 2
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mov rbp, rsp
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mov r1, [rbp-6]
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mov r0, [counter]
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add r0, vcd_base
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cmp r1, ' '
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mov r2, rfl
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and r2, fl_eq
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jnz r2, .incr
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mov byte [r0], r1
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.incr:
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mov r0, [counter]
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add r0, 1
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mov [counter], r0
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.leave:
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mov rsp, rbp
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sub rsp, 2
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mov rbp, [rsp]
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ret
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print_u16:
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mov [rsp], rbp
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add rsp, 2
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mov rbp, rsp
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mov r1, [rbp-6] ; value to print
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mov r2, 0 ; place index
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jmp .digits_cond
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.digits_body:
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mov r3, .places
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add r3, r2
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mov r3, [r3] ; place
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mov r4, 0 ; place occurences
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jmp .place_cond
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.place_body:
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add r4, 1
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sub r1, r3
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.place_cond:
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cmp r3, r1
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mov r0, rfl
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and r0, fl_eq | fl_lt
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jnz r0, .place_body
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mov r0, r4
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add r0, 48
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add rsp, 4
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mov [rsp-4], r1
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mov [rsp-2], r2
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mov [rsp], r0
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add rsp, 2
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call term_putc
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sub rsp, 2
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mov r2, [rsp-2]
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mov r1, [rsp-4]
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sub rsp, 4
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add r2, 2
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.digits_cond:
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cmp r2, 10
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mov r0, rfl
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and r0, fl_lt
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jnz r0, .digits_body
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.leave:
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mov rsp, rbp
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sub rsp, 2
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mov rbp, [rsp]
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ret
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.places:
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dw 10000, 1000, 100, 10, 1
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