ch8_isa/data/
key_data.rs

1/*
2 * key_data.rs
3 * Defines a struct that holds data for the KEY instruction
4 * Created on 12/6/2019
5 * Created by Andrew Davis
6 *
7 * Copyright (C) 2019  Andrew Davis
8 *
9 * This program is free software: you can redistribute it and/or modify   
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation, either version 3 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17 * GNU General Public License for more details.
18 * 
19 * You should have received a copy of the GNU General Public License
20 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
21 */
22
23//usage statements
24use super::Register;
25use super::super::codegen::CodeGen;
26
27/// Contextual data for the `KEY` instruction
28pub struct KeyData {
29    /// The register to read the keypress into
30    vx: Register 
31}
32
33//implementation
34impl KeyData {
35    /// Constructs a new `KeyData` instance
36    ///
37    /// # Argument
38    ///
39    /// * `new_vx` - The register to read the keypress into
40    /// 
41    /// # Panics
42    ///
43    /// This method will panic if `new_vx` refers to the `I` register.
44    /// 
45    /// # Returns 
46    ///
47    /// A new `KeyData` instance with the given properties
48    pub fn new(new_vx: Register) -> KeyData {
49        //validate the register
50        if new_vx == Register::I {
51            panic!("Cannot read keypress into index register");
52        }
53
54        //and return the instance
55        return KeyData {
56            vx: new_vx 
57        };
58    }
59}
60
61//CodeGen implementation
62impl CodeGen for KeyData {
63    /// Generates an opcode for the `KEY` instruction from the data 
64    /// 
65    /// # Returns
66    ///
67    /// The generated opcode
68    fn gen_opcode(&self) -> u16 {
69        return 0xF00A | ((self.vx.to_id() as u16) << 8);
70    }
71}
72
73//unit tests
74#[cfg(test)]
75mod tests {
76    //import the KeyData struct
77    use super::*;
78
79    //this test checks that the I register cannot be used
80    #[test]
81    #[should_panic]
82    fn test_cannot_read_key_into_index() {
83        let _b = KeyData::new(Register::I);
84    }
85
86    //this test checks opcode generation
87    #[test]
88    fn test_opcode_gen() {
89        let gdld = KeyData::new(Register::V1);
90        assert_eq!(gdld.gen_opcode(), 0xF10A);
91    }
92}
93
94//end of file
ch8_isa/data/key_data.rs

ch8_isa/data/
key_data.rs
