51 lines
1.6 KiB
Rust
51 lines
1.6 KiB
Rust
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/**
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* The system device
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*/
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#[derive(Debug)]
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struct SystemDevice {
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buffer: [u8; 0xF],
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}
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impl SystemDevice {
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fn new() -> SystemDevice {
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SystemDevice { buffer: [0; 0xF] }
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}
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}
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impl Device for SystemDevice {
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fn dei1(&mut self, vm: &mut Uxn, port: u8) -> u8 {
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let slot = port & 0xF;
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match slot {
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0x2 => vm.wst.idx,
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0x3 => vm.rst.idx,
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x => self.buffer[x as usize],
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}
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}
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fn dei2(&mut self, vm: &mut Uxn, port: u8) -> u16 {
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return ((self.dei1(vm, port) as u16) << 8) + self.dei1(vm, port + 1) as u16;
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}
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fn deo1(&mut self, vm: &mut Uxn, port: u8, val: u8) {
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let slot = port & 0xF;
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match slot {
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// Note: This VM does not support mutating the stack pointers.
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// This operation is not well defined upstream
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0x2 => panic!("Invoked unsupported mutation of the data stack pointer"),
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0x3 => panic!("Invoked unsupported mutation of the return stack pointer"),
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x => self.buffer[x as usize] = val,
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}
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}
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fn deo2(&mut self, vm: &mut Uxn, port: u8, val: u16) {
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let slot = port & 0xF;
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assert!(slot < 0xF, "Double-write beyond the end of the device");
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match slot {
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0x2 => panic!("The data stack is single-width, panic on spurious double-write"),
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0x3 => panic!("The return stack is single-width, panic on spurious double-write"),
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x => {
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let [high, low] = val.to_be_bytes();
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self.deo1(vm, x, high);
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self.deo1(vm, x + 1, low)
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}
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}
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}
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}
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