k580-core 2.0.0

KR580VM80 / Intel 8080 CPU core for KR580.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92

use crate::Cpu8080State;

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub(crate) enum RegPair {
    BC,
    DE,
    HL,
    SP,
}

impl RegPair {
    pub(crate) fn from_code(code: u8) -> Self {
        match code & 0x03 {
            0 => Self::BC,
            1 => Self::DE,
            2 => Self::HL,
            _ => Self::SP,
        }
    }
}

impl Cpu8080State {
    /// `&mut self` because the M=`(HL)` arm goes through the bus
    /// latches; the other seven register codes are internal-only.
    pub(crate) fn read_reg_code(&mut self, code: u8) -> u8 {
        match code & 0x07 {
            0 => self.registers.b,
            1 => self.registers.c,
            2 => self.registers.d,
            3 => self.registers.e,
            4 => self.registers.h,
            5 => self.registers.l,
            6 => self.bus_read(self.registers.hl()),
            _ => self.registers.a,
        }
    }

    pub(crate) fn write_reg_code(&mut self, code: u8, value: u8) {
        match code & 0x07 {
            0 => self.registers.b = value,
            1 => self.registers.c = value,
            2 => self.registers.d = value,
            3 => self.registers.e = value,
            4 => self.registers.h = value,
            5 => self.registers.l = value,
            6 => self.bus_write(self.registers.hl(), value),
            _ => self.registers.a = value,
        }
    }

    pub(crate) fn read_pair(&self, pair: RegPair) -> u16 {
        match pair {
            RegPair::BC => self.registers.bc(),
            RegPair::DE => self.registers.de(),
            RegPair::HL => self.registers.hl(),
            RegPair::SP => self.sp,
        }
    }

    pub(crate) fn write_pair(&mut self, pair: RegPair, value: u16) {
        match pair {
            RegPair::BC => self.registers.set_bc(value),
            RegPair::DE => self.registers.set_de(value),
            RegPair::HL => self.registers.set_hl(value),
            RegPair::SP => self.sp = value,
        }
    }

    pub(crate) fn fetch_byte(&mut self, offset: u16) -> u8 {
        self.bus_read(self.pc.wrapping_add(offset))
    }

    pub(crate) fn fetch_word(&mut self, offset: u16) -> u16 {
        self.bus_read_word(self.pc.wrapping_add(offset))
    }

    pub(crate) fn push_word(&mut self, value: u16) {
        let [hi, lo] = value.to_be_bytes();
        self.sp = self.sp.wrapping_sub(1);
        self.bus_write(self.sp, hi);
        self.sp = self.sp.wrapping_sub(1);
        self.bus_write(self.sp, lo);
    }

    pub(crate) fn pop_word(&mut self) -> u16 {
        let lo = self.bus_read(self.sp);
        self.sp = self.sp.wrapping_add(1);
        let hi = self.bus_read(self.sp);
        self.sp = self.sp.wrapping_add(1);
        u16::from_be_bytes([hi, lo])
    }
}