82 lines
2.2 KiB
Rust
82 lines
2.2 KiB
Rust
use anyhow::Result;
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use rand::Rng;
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use std::{
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fs::{self, File},
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io::{Read, Seek as _, SeekFrom, Write as _},
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path::{Path, PathBuf},
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};
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use crate::emulator::SimId;
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pub struct Cart {
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pub file_path: PathBuf,
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pub rom: Vec<u8>,
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sram_file: File,
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pub sram: Vec<u8>,
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}
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impl Cart {
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pub fn load(file_path: &Path, sim_id: SimId) -> Result<Self> {
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let rom = fs::read(file_path)?;
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let rom = try_parse_elf(&rom).unwrap_or(rom);
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let mut sram_file = File::options()
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.read(true)
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.write(true)
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.create(true)
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.truncate(false)
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.open(sram_path(file_path, sim_id))?;
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let sram = if sram_file.metadata()?.len() == 0 {
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// new SRAM file, randomize the contents
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let mut sram = vec![0; 16 * 1024];
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let mut rng = rand::rng();
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for dst in sram.iter_mut().step_by(2) {
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*dst = rng.random();
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}
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sram
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} else {
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let mut sram = Vec::with_capacity(16 * 1024);
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sram_file.read_to_end(&mut sram)?;
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sram
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};
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Ok(Cart {
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file_path: file_path.to_path_buf(),
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rom,
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sram_file,
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sram,
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})
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}
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pub fn save_sram(&mut self) -> Result<()> {
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self.sram_file.seek(SeekFrom::Start(0))?;
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self.sram_file.write_all(&self.sram)?;
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Ok(())
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}
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}
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fn try_parse_elf(data: &[u8]) -> Option<Vec<u8>> {
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let parsed = elf::ElfBytes::<elf::endian::AnyEndian>::minimal_parse(data).ok()?;
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let mut bytes = vec![];
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let mut pstart = None;
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for phdr in parsed.segments()? {
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if phdr.p_filesz == 0 {
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continue;
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}
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let start = pstart.unwrap_or(phdr.p_paddr);
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pstart = Some(start);
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bytes.resize((phdr.p_paddr - start) as usize, 0);
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let data = parsed.segment_data(&phdr).ok()?;
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bytes.extend_from_slice(data);
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}
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Some(bytes)
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}
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fn sram_path(file_path: &Path, sim_id: SimId) -> PathBuf {
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match sim_id {
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SimId::Player1 => file_path.with_extension("p1.sram"),
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SimId::Player2 => file_path.with_extension("p2.sram"),
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}
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}
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