141 lines
1.9 KiB
NASM
141 lines
1.9 KiB
NASM
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start:
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; rsp points *at* the top element
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mov Rbp, 2048
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mov rsp, 2048 - 2
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lit interrupt_table
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or rfl, rfl, 1 << Fl_Int
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or rfl, Rfl, 1 << Fl_Vcd
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mov16 r0, 512
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mov16 r1, 1
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int Int_DiskRead
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main_loop:
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hlt
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jmp main_loop
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interrupt_table:
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; size
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d16 1
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data keyboard_interrupt
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nop
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keyboard_interrupt:
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and rfl, rfl, !(1 << Fl_Int)
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push rbp
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mov rbp, Rsp
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push r0
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push r1
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push r2
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push r3
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in r0, Device_Keyboard
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cmp r0, 44
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mov r1, rfl
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and r1, r1, 1 << Fl_Eq
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jnz r1, .L0
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cmp r0, 42
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mov16 r1, rfl
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and r1, r1, 1 << Fl_Eq
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jnz r1, .L1
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cmp r0, 40
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mov r1, rfl
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and r1, r1, 1 << Fl_Eq
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jnz r1, .L2
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jmp .L3
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.L0:
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mov R0, 32 ; ' '
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call put_char
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jmp .L4
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.L1:
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mov r1, screen_x
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cmp r1, 0
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mov r2, rfl
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and r2, r2, 1 << Fl_Eq
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jnz r2, .L4
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sub r1, r1, 1
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mov screen_x, R1
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; mov r0, ' '
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call put_char
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mov16 r1, screen_x
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sub r1, r1, 1
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mov screen_x, R1
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jmp .L4
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.L2:
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mov r1, screen_y
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add r1, r1, 1
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mov screen_y, R1
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mov r1, 0
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mov screen_x, R1
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jmp .L4
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.L3:
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; add r0, r0, 'A' - 4
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call put_char
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jmp .L4
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.L4:
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pop r3
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pop r2
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pop r1
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pop r0
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mov rsp, rbp
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pop rbp
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or rfl, rfl, 1 << Fl_Int
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iret
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put_char:
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push rbp
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mov rbp, rsp
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push r1
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push r2
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mov r2, screen_y
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mul r2, r2, vcd_width_in_ch
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mov r1, screen_x
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add r1, r1, 0x0c00
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add r1, r1, r2
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mov r1, r0
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mov r1, screen_x
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add r1, r1, 1
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mov screen_x, r1
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cmp r1, vcd_width_in_ch
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mov r2, rfl
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and r2, r2, 1 << Fl_Eq
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jnz r2, .L0
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jmp .L1
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.L0:
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mov r1, screen_y
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add r1, r1, 1
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mov screen_y, r1
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mov r1, 0
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mov screen_x, r1
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.L1:
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pop r1
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pop r2
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mov rsp, rbp
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pop rbp
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ret
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screen_x:
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d16 0
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screen_y:
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d16 0
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; vim: syntax=nasm
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