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| author | Adam Carpenter <53hornet@gmail.com> | 2019-03-27 15:32:37 -0400 |
|---|---|---|
| committer | Adam Carpenter <53hornet@gmail.com> | 2019-03-27 15:32:37 -0400 |
| commit | 67cdcc2e12118becb823e20a40cc2687f2b8425a (patch) | |
| tree | ed92c3234b89079e6d4cf36f5e80c5ffa79def48 /meap/meap-code/ch5/ch5-cpu2/src/main.rs | |
| parent | e25482fca375d318a39c3b54db396b0db6e0b263 (diff) | |
| download | learning-rust-67cdcc2e12118becb823e20a40cc2687f2b8425a.tar.xz learning-rust-67cdcc2e12118becb823e20a40cc2687f2b8425a.zip | |
Started Rust in Action MEAP.
Diffstat (limited to 'meap/meap-code/ch5/ch5-cpu2/src/main.rs')
| -rw-r--r-- | meap/meap-code/ch5/ch5-cpu2/src/main.rs | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/meap/meap-code/ch5/ch5-cpu2/src/main.rs b/meap/meap-code/ch5/ch5-cpu2/src/main.rs new file mode 100644 index 0000000..8271ca8 --- /dev/null +++ b/meap/meap-code/ch5/ch5-cpu2/src/main.rs @@ -0,0 +1,60 @@ +const HALT: u8 = 0x0;
+const ARITHMETIC_AND_LOGIC: u8 = 0x8;
+const ADD_XY: u8 = 0x4;
+
+struct CPU {
+ // current_operation: u16, // no longer needed
+ registers: [u8; 16], // increase number of registers to 16 (0..F), as per CHIP-8
+ position_in_memory: usize, // add a program counter.. using a usize to simplify array indexing
+ memory: [u8; 4096], // give the system 4kb memory
+}
+
+impl CPU {
+ fn run(&mut self) {
+ loop {
+ let op_byte1 = self.memory[self.position_in_memory] as u16; //
+ let op_byte2 = self.memory[self.position_in_memory + 1] as u16; //
+ let raw_op = op_byte1 << 8 | op_byte2;
+
+ self.position_in_memory += 2;
+
+ let op_major = ((raw_op & 0xF000) >> 12) as u8;
+ let x = ((raw_op & 0x0F00) >> 8) as u8;
+ let y = ((raw_op & 0x00F0) >> 4) as u8;
+ let op_minor = (raw_op & 0x000F) as u8;
+
+ match (op_major, op_minor) {
+ (HALT, HALT) => { return; },
+ (ARITHMETIC_AND_LOGIC, ADD_XY) => self.add_xy(x, y),
+ _ => unimplemented!("opcode {:04x}", raw_op), // this macro is useful when you are debugging, as it will promptly indicate that you have made a typo
+ }
+ }
+ }
+
+ fn add_xy(&mut self, x: u8, y: u8) {
+ self.registers[x as usize] += self.registers[y as usize];
+ }
+}
+
+fn main() {
+ let mut cpu = CPU {
+ registers: [0; 16],
+ memory: [0; 4096],
+ position_in_memory: 0,
+ };
+
+ cpu.registers[0] = 5;
+ cpu.registers[1] = 10;
+ cpu.registers[2] = 10; // initialise a few more registers
+ cpu.registers[3] = 10; //
+
+ cpu.memory[0] = 0x80; cpu.memory[1] = 0x14; // 0x8014 -> ADD register 1 to register 0
+ cpu.memory[2] = 0x80; cpu.memory[3] = 0x24; // 0x8014 -> ADD register 2 to register 0
+ cpu.memory[4] = 0x80; cpu.memory[5] = 0x34; // 0x8014 -> ADD register 3 to register 0
+
+ cpu.run();
+
+ assert_eq!(cpu.registers[0], 35);
+
+ println!("5 + 10 + 10 + 10 = {}", cpu.registers[0]);
+}
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