ch8_isa/data/
shl_data.rs

1/*
2 * shl_data.rs
3 * Defines a struct that holds data for the SHL instruction
4 * Created on 12/5/2019
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 `SHL` instruction
28pub struct ShlData {
29    /// The register to shift
30    vx: Register 
31}
32
33//implementation
34impl ShlData {
35    /// Constructs a new `ShlData` instance
36    ///
37    /// # Argument
38    ///
39    /// * `new_vx` - The register to shift left
40    /// 
41    /// # Panics
42    ///
43    /// This method will panic if `new_vx` refers to the `I` register.
44    /// 
45    /// # Returns
46    ///
47    /// A new `ShlData` instance with the given properties
48    pub fn new(new_vx: Register) -> ShlData {
49        //validate the register
50        if new_vx == Register::I {
51            panic!("Index register cannot be shifted");
52        }
53
54        //and return the instance
55        return ShlData {
56            vx: new_vx 
57        }
58    }
59}
60
61//CodeGen implementation
62impl CodeGen for ShlData {
63    /// Generates an opcode for the `SHL` instruction
64    /// 
65    /// # Returns
66    ///
67    /// The opcode generated from the data
68    fn gen_opcode(&self) -> u16 {
69        let mut code = 0x800E;
70        code |= (self.vx.to_id() as u16) << 8;
71        code |= (self.vx.to_id() as u16) << 4;
72        return code;
73    }
74}
75
76//unit tests
77#[cfg(test)]
78mod tests {
79    //import the ShlData struct
80    use super::*;
81
82    //this test checks that the I register cannot be shifted
83    #[test]
84    #[should_panic]
85    fn test_cannot_shift_index() {
86        let _bd = ShlData::new(Register::I);
87    }
88
89    //this test checks opcode generation
90    #[test]
91    fn test_opcode_gen() {
92        let shld = ShlData::new(Register::V1);
93        assert_eq!(shld.gen_opcode(), 0x811E);
94    }
95}
96
97//end of file
ch8_isa/data/shl_data.rs

ch8_isa/data/
shl_data.rs
