c64_assembler/memory/
mod.rs

1pub mod address_mode;
2pub mod define;
3pub mod label;
4pub mod user_count;
5
6/// Memory address
7pub type Address = u16;
8
9/// Trait for instructions that can handle zeropage and regular addresses.
10///
11/// Zeropage are special address mode on the 6502 where less CPU-cycles and
12/// instruction size is used when accessing RAM below 0x0100.
13///
14/// Based on the is_zeropage the caller can decide if it only needs the low byte or
15/// both the low and high byte.
16pub trait ZeroPage {
17    /// Is the address a zeropage address
18    fn is_zeropage(&self) -> bool;
19
20    /// Get the lower byte of the address
21    fn low(&self) -> u8;
22
23    /// Get the higher byte of the address
24    fn high(&self) -> u8;
25}
26
27impl ZeroPage for Address {
28    /// Is the address a zeropage address
29    ///
30    /// ```
31    /// use c64_assembler::memory::ZeroPage;
32    ///
33    /// assert_eq!(true, 0x00FE.is_zeropage());
34    /// assert_eq!(true, 0x00FF.is_zeropage());
35    /// assert_eq!(false, 0x0100.is_zeropage());
36    /// assert_eq!(false, 0x0101.is_zeropage());
37    /// ```
38    fn is_zeropage(&self) -> bool {
39        *self < 0x100
40    }
41
42    /// Get the lower byte of the address
43    ///
44    /// ```
45    /// use c64_assembler::memory::ZeroPage;
46    ///
47    /// assert_eq!(0xFE, 0x00FE.low());
48    /// assert_eq!(0xFF, 0x00FF.low());
49    /// assert_eq!(0x00, 0x0100.low());
50    /// assert_eq!(0x01, 0x0101.low());
51    /// ```
52    fn low(&self) -> u8 {
53        (self & 0xFF) as u8
54    }
55
56    /// Get the higher byte of the address
57    ///
58    /// ```
59    /// use c64_assembler::memory::ZeroPage;
60    ///
61    /// assert_eq!(0x00, 0x00FE.high());
62    /// assert_eq!(0x00, 0x00FF.high());
63    /// assert_eq!(0x01, 0x0100.high());
64    /// assert_eq!(0x01, 0x0101.high());
65    /// ```
66    fn high(&self) -> u8 {
67        (self >> 8) as u8
68    }
69}
c64_assembler/memory/mod.rs

c64_assembler/memory/
mod.rs
