554edd62b0
Serde doesn't like Rc that much :( Fixes #142 Former-commit-id: e1e8a96b4867e351d103fb7d92d71b0434e8fc31 Former-commit-id: 28366bbb36b3e93b574f397b103a483844fd8131
223 lines
6.4 KiB
Rust
223 lines
6.4 KiB
Rust
use super::interrupt::{self, Interrupt, InterruptConnect, SharedInterruptFlags};
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use super::iodev::consts::*;
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use super::sysbus::SysBus;
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use num::FromPrimitive;
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use serde::{Deserialize, Serialize};
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const SHIFT_LUT: [usize; 4] = [0, 6, 8, 10];
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#[derive(Serialize, Deserialize, Clone, Debug)]
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pub struct Timer {
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// registers
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pub ctl: TimerCtl,
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pub data: u16,
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pub initial_data: u16,
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irq: Interrupt,
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interrupt_flags: SharedInterruptFlags,
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timer_id: usize,
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cycles: usize,
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prescalar_shift: usize,
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}
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impl Timer {
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pub fn new(timer_id: usize, interrupt_flags: SharedInterruptFlags) -> Timer {
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if timer_id > 3 {
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panic!("invalid timer id {}", timer_id);
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}
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Timer {
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timer_id: timer_id,
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irq: Interrupt::from_usize(timer_id + 3).unwrap(),
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interrupt_flags,
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data: 0,
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ctl: TimerCtl(0),
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initial_data: 0,
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cycles: 0,
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prescalar_shift: 0,
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}
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}
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#[inline]
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fn ticks_to_overflow(&self) -> u32 {
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0x1_0000 - (self.data as u32)
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}
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/// increments the timer with an amount of ticks
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/// returns the number of times it overflowed
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fn update(&mut self, ticks: usize) -> usize {
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let mut ticks = ticks as u32;
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let mut num_overflows = 0;
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let ticks_remaining = self.ticks_to_overflow();
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if ticks >= ticks_remaining {
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num_overflows += 1;
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ticks -= ticks_remaining;
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self.data = self.initial_data;
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let ticks_remaining = self.ticks_to_overflow();
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num_overflows += ticks / ticks_remaining;
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ticks = ticks % ticks_remaining;
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if self.ctl.irq_enabled() {
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interrupt::signal_irq(&self.interrupt_flags, self.irq);
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}
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}
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self.data += ticks as u16;
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num_overflows as usize
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}
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}
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#[derive(Serialize, Deserialize, Clone, Debug)]
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pub struct Timers {
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timers: [Timer; 4],
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running_timers: u8,
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pub trace: bool,
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}
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impl InterruptConnect for Timers {
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fn connect_irq(&mut self, interrupt_flags: SharedInterruptFlags) {
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for timer in &mut self.timers {
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timer.interrupt_flags = interrupt_flags.clone();
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}
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}
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}
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impl std::ops::Index<usize> for Timers {
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type Output = Timer;
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fn index(&self, index: usize) -> &Self::Output {
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&self.timers[index]
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}
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}
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impl std::ops::IndexMut<usize> for Timers {
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fn index_mut(&mut self, index: usize) -> &mut Self::Output {
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&mut self.timers[index]
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}
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}
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impl Timers {
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pub fn new(interrupt_flags: SharedInterruptFlags) -> Timers {
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Timers {
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timers: [
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Timer::new(0, interrupt_flags.clone()),
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Timer::new(1, interrupt_flags.clone()),
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Timer::new(2, interrupt_flags.clone()),
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Timer::new(3, interrupt_flags.clone()),
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],
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running_timers: 0,
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trace: false,
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}
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}
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pub fn write_timer_ctl(&mut self, id: usize, value: u16) {
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let new_ctl = TimerCtl(value);
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let old_enabled = self[id].ctl.enabled();
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let new_enabled = new_ctl.enabled();
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let cascade = new_ctl.cascade();
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self[id].cycles = 0;
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self[id].prescalar_shift = SHIFT_LUT[new_ctl.prescalar() as usize];
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self[id].ctl = new_ctl;
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if new_enabled && !cascade {
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self.running_timers |= 1 << id;
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} else {
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self.running_timers &= !(1 << id);
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}
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if old_enabled != new_enabled {
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trace!(
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"TMR{} {}",
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id,
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if new_enabled { "enabled" } else { "disabled" }
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);
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}
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}
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pub fn handle_read(&self, io_addr: u32) -> u16 {
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match io_addr {
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REG_TM0CNT_L => self.timers[0].data,
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REG_TM0CNT_H => self.timers[0].ctl.0,
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REG_TM1CNT_L => self.timers[1].data,
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REG_TM1CNT_H => self.timers[1].ctl.0,
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REG_TM2CNT_L => self.timers[2].data,
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REG_TM2CNT_H => self.timers[2].ctl.0,
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REG_TM3CNT_L => self.timers[3].data,
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REG_TM3CNT_H => self.timers[3].ctl.0,
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_ => unreachable!(),
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}
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}
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pub fn handle_write(&mut self, io_addr: u32, value: u16) {
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match io_addr {
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REG_TM0CNT_L => {
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self.timers[0].data = value;
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self.timers[0].initial_data = value;
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}
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REG_TM0CNT_H => self.write_timer_ctl(0, value),
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REG_TM1CNT_L => {
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self.timers[1].data = value;
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self.timers[1].initial_data = value;
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}
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REG_TM1CNT_H => self.write_timer_ctl(1, value),
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REG_TM2CNT_L => {
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self.timers[2].data = value;
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self.timers[2].initial_data = value;
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}
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REG_TM2CNT_H => self.write_timer_ctl(2, value),
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REG_TM3CNT_L => {
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self.timers[3].data = value;
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self.timers[3].initial_data = value;
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}
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REG_TM3CNT_H => self.write_timer_ctl(3, value),
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_ => unreachable!(),
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}
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}
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pub fn update(&mut self, cycles: usize, sb: &mut SysBus) {
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for id in 0..4 {
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if self.running_timers & (1 << id) == 0 {
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continue;
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}
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if !self.timers[id].ctl.cascade() {
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let timer = &mut self.timers[id];
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let cycles = timer.cycles + cycles;
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let inc = cycles >> timer.prescalar_shift;
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let num_overflows = timer.update(inc);
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timer.cycles = cycles & ((1 << timer.prescalar_shift) - 1);
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if num_overflows > 0 {
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if id != 3 {
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let next_timer = &mut self.timers[id + 1];
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if next_timer.ctl.cascade() {
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next_timer.update(num_overflows);
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}
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}
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if id == 0 || id == 1 {
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sb.io
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.sound
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.handle_timer_overflow(&mut sb.io.dmac, id, num_overflows);
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}
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}
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}
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}
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}
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}
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bitfield! {
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#[derive(Serialize, Deserialize, Clone, Default)]
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pub struct TimerCtl(u16);
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impl Debug;
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u16;
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prescalar, _ : 1, 0;
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cascade, _ : 2;
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irq_enabled, _ : 6;
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enabled, set_enabled : 7;
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}
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