neocturne/MinedMap
1
0
Fork 0
mirror of https://github.com/neocturne/MinedMap.git synced 2025-03-05 01:24:53 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

io/region: return sorted Vec instead of HashMap from parse_header()

Browse source 
Instead of counting and looking up indices in the HashMap, we can just
iterate over all offsets in the returned Vec.
This commit is contained in:
Matthias Schiffer 2023-01-30 19:08:51 +01:00
parent 6186a0d916
commit 8c34f74952
Signed by: neocturne
GPG key ID: 16EF3F64CB201D9C
1 changed files with 29 additions and 25 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

54
src/io/region.rs
View file

@ -1,5 +1,4 @@
use std::{
collections::HashMap,
fs::File,
io::{prelude::*, SeekFrom},
path::Path,
@ -15,27 +14,35 @@ const BLOCKSIZE: usize = 4096;
#[derive(Debug)]
struct ChunkDesc {
coords: ChunkCoords,
offset: u32,
len: u8,
coords: ChunkCoords,
}
fn parse_header(header: &ChunkArray<u32>) -> HashMap<u32, ChunkDesc> {
let mut map = HashMap::new();
fn parse_header(header: &ChunkArray<u32>) -> Vec<ChunkDesc> {
let mut chunks: Vec<_> = header
.iter()
.filter_map(|(coords, &chunk)| {
let offset_len = u32::from_be(chunk);
for (coords, &chunk) in header.iter() {
let offset_len = u32::from_be(chunk);
let offset = offset_len >> 8;
let len = offset_len as u8;
let offset = offset_len >> 8;
let len = offset_len as u8;
if offset == 0 || len == 0 {
return None;
}
if offset == 0 || len == 0 {
continue;
}
Some(ChunkDesc {
offset,
len,
coords,
})
})
.collect();
map.insert(offset, ChunkDesc { coords, len });
}
chunks.sort_by_key(|chunk| chunk.offset);
map
chunks
}
fn decode_chunk<T>(buf: &[u8]) -> Result<T>
@ -70,7 +77,7 @@ impl<R: Read + Seek> Region<R> {
{
let Region { mut reader } = self;
let mut chunk_map = {
let chunks = {
let mut header = ChunkArray::<u32>::default();
reader
.read_exact(bytemuck::cast_mut::<_, [u8; BLOCKSIZE]>(&mut header.0))
@ -79,22 +86,21 @@ impl<R: Read + Seek> Region<R> {
parse_header(&header)
};
let mut index = 1;
let mut seen = ChunkArray::<bool>::default();
while !chunk_map.is_empty() {
let Some(ChunkDesc { coords, len }) = chunk_map.remove(&index) else {
index += 1;
continue;
};
for ChunkDesc {
offset,
len,
coords,
} in chunks
{
if seen[coords] {
bail!("Duplicate chunk {:?}", coords);
}
seen[coords] = true;
reader
.seek(SeekFrom::Start(index as u64 * BLOCKSIZE as u64))
.seek(SeekFrom::Start(offset as u64 * BLOCKSIZE as u64))
.context("Failed to seek chunk data")?;
let mut len_buf = [0u8; 4];
@ -114,8 +120,6 @@ impl<R: Read + Seek> Region<R> {
.with_context(|| format!("Failed to decode data for chunk {:?}", coords))?;
f(coords, chunk);
index += len as u32;
}
Ok(())