62 lines
1.7 KiB
Rust
62 lines
1.7 KiB
Rust
use super::Addr;
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use std::io;
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use std::ops::Add;
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use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
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pub enum MemoryAccessType {
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NonSeq,
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Seq,
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}
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pub enum MemoryAccessWidth {
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MemoryAccess8,
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MemoryAccess16,
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MemoryAccess32,
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}
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impl Add<MemoryAccessWidth> for MemoryAccessType {
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type Output = MemoryAccess;
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fn add(self, other: MemoryAccessWidth) -> Self::Output {
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MemoryAccess(self, other)
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}
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}
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pub struct MemoryAccess(pub MemoryAccessType, pub MemoryAccessWidth);
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pub trait Bus {
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fn read_32(&self, addr: Addr) -> u32 {
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self.get_bytes(addr, 4).read_u32::<LittleEndian>().unwrap()
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}
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fn read_16(&self, addr: Addr) -> u16 {
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self.get_bytes(addr, 2).read_u16::<LittleEndian>().unwrap()
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}
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fn read_8(&self, addr: Addr) -> u8 {
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self.get_bytes(addr, 1)[0]
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}
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fn write_32(&mut self, addr: Addr, value: u32) -> Result<(), io::Error> {
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self.get_bytes_mut(addr, 4).write_u32::<LittleEndian>(value)
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}
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fn write_16(&mut self, addr: Addr, value: u16) -> Result<(), io::Error> {
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self.get_bytes_mut(addr, 2).write_u16::<LittleEndian>(value)
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}
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fn write_8(&mut self, addr: Addr, value: u8) -> Result<(), io::Error> {
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self.get_bytes_mut(addr, 1).write_u8(value)
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}
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/// Return a slice of bytes
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/// Will panic if requested range is out of bounds
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fn get_bytes(&self, addr: Addr, len: usize) -> &[u8];
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/// Return a mutable slice of bytes
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/// Will panic if requested range is out of bounds
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fn get_bytes_mut(&mut self, addr: Addr, len: usize) -> &mut [u8];
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/// returns the number of cycles needed for this memory access
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fn get_cycles(&self, addr: Addr, access: MemoryAccess) -> usize;
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}
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