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rustboyadvance-ng/src/arm7tdmi/bus.rs
Michel Heily be9499c76d Move cycle counting to CPU Core
This isn't accurate, I'm probably missing something but at least it'll
make the instruction implementation more clean for now..


Former-commit-id: de24b15e1a51e1998207e5ea96fc8543f2553a26
2019-07-05 13:08:07 +03:00

84 lines
2.1 KiB
Rust

use std::fmt;
use std::io;
use std::ops::Add;
use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
use super::Addr;
#[derive(Debug)]
pub enum MemoryAccessType {
NonSeq,
Seq,
}
impl fmt::Display for MemoryAccessType {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"{}",
match self {
MemoryAccessType::NonSeq => "N",
MemoryAccessType::Seq => "S",
}
)
}
}
#[derive(Debug)]
pub enum MemoryAccessWidth {
MemoryAccess8,
MemoryAccess16,
MemoryAccess32,
}
impl Add<MemoryAccessWidth> for MemoryAccessType {
type Output = MemoryAccess;
fn add(self, other: MemoryAccessWidth) -> Self::Output {
MemoryAccess(self, other)
}
}
#[derive(Debug)]
pub struct MemoryAccess(pub MemoryAccessType, pub MemoryAccessWidth);
impl fmt::Display for MemoryAccess {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}-Cycle ({:?})", self.0, self.1)
}
}
pub trait Bus {
fn read_32(&self, addr: Addr) -> u32 {
self.get_bytes(addr).read_u32::<LittleEndian>().unwrap()
}
fn read_16(&self, addr: Addr) -> u16 {
self.get_bytes(addr).read_u16::<LittleEndian>().unwrap()
}
fn read_8(&self, addr: Addr) -> u8 {
self.get_bytes(addr)[0]
}
fn write_32(&mut self, addr: Addr, value: u32) -> Result<(), io::Error> {
self.get_bytes_mut(addr).write_u32::<LittleEndian>(value)
}
fn write_16(&mut self, addr: Addr, value: u16) -> Result<(), io::Error> {
self.get_bytes_mut(addr).write_u16::<LittleEndian>(value)
}
fn write_8(&mut self, addr: Addr, value: u8) -> Result<(), io::Error> {
self.get_bytes_mut(addr).write_u8(value)
}
/// Return a slice of bytes
fn get_bytes(&self, addr: Addr) -> &[u8];
/// Return a mutable slice of bytes
fn get_bytes_mut(&mut self, addr: Addr) -> &mut [u8];
/// returns the number of cycles needed for this memory access
fn get_cycles(&self, addr: Addr, access: MemoryAccess) -> usize;
}