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millfork/include/gb_joy.mfk
2021-07-11 18:15:39 -04:00

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#if not(GAMEBOY)
#warn gb_joy module should be only used on Game Boy targets
#endif
import gb_hardware
#pragma zilog_syntax
// standard joystick driver for Game Boy
import joy
alias input_a = input_btn
byte input_b
byte input_select
byte input_start
void read_joy() {
byte tmp
reg_joypad = $20
asm {
ld a,(reg_joypad)
ld a,(reg_joypad)
ld a,(reg_joypad)
ld a,(reg_joypad)
}
tmp = reg_joypad
input_dx = 0
input_dy = 0
if tmp & 1 == 0 { input_dx += 1 }
if tmp & 2 == 0 { input_dx -= 1 }
if tmp & 4 == 0 { input_dy -= 1 }
if tmp & 8 == 0 { input_dy += 1 }
reg_joypad = $10
asm {
ld a,(reg_joypad)
ld a,(reg_joypad)
ld a,(reg_joypad)
ld a,(reg_joypad)
}
tmp = reg_joypad ^ $ff
input_a = (tmp & 1) // >> 0
input_b = (tmp & 2) >> 1
input_select = (tmp & 4) >> 2
input_start = (tmp & 8) >> 3
}