Work on extraction

Created DataExtractor & DataReader
Created Lookup tables

src/data/extractor.zig

@@ -0,0 +1,102 @@
+const std = @import("std");
+const Io = std.Io;
+
+const DecompCache = @import("../decomp_cache.zig");
+const DataBlock = @import("../inode.zig").DataBlock;
+
+const Extractor = @This();
+
+cache: *DecompCache,
+block_size: u32,
+
+start: u64,
+size: u64,
+blocks: []DataBlock,
+
+frag_data: ?[]u8 = null,
+frag_offset: u32 = 0,
+
+pub fn init(cache: *DecompCache, block_size: u32, size: u64, start: u64, blocks: []DataBlock) Extractor {
+    return .{
+        .cache = cache,
+        .block_size = block_size,
+
+        .start = start,
+        .size = size,
+        .blocks = blocks,
+    };
+}
+
+pub fn addFragment(self: *Extractor, data: []u8, offset: u32) void {
+    self.frag_data = data;
+    self.frag_offset = offset;
+}
+
+pub fn asyncExtract(self: Extractor, io: Io, fil: Io.File) Error!void {
+    try fil.writePositionalAll(io, &.{&.{0}}, self.size - 1);
+
+    var map = try fil.createMemoryMap(io, .{ .len = self.size, .protection = .{ .write = true } });
+    defer map.destroy(io);
+
+    var group: Io.Group = .init;
+    defer group.cancel(io);
+
+    var ret_err: ?Error = null;
+
+    var offset = self.start;
+    for (0..self.blocks.len) |i| {
+        group.async(io, blockThread, .{ self, io, map, offset, i, &ret_err });
+
+        offset += self.blocks[i].size;
+    }
+    if (self.frag_data != null)
+        group.async(io, fragThread, .{ self, map });
+
+    group.await(io) catch |err| return ret_err orelse err;
+
+    try map.write(io);
+}
+
+fn blockThread(self: Extractor, io: Io, map: Io.File.MemoryMap, read_offset: u64, idx: usize, ret_err: *?Error) error{Canceled}!void {
+    const write_pos = idx * self.block_size;
+    const size = if (self.frag_data == null and idx == self.block_size.len - 1)
+        self.size % self.block_size
+    else
+        self.block_size;
+    const block = self.blocks[idx];
+
+    if (block.size == 0) {
+        @memset(map.memory[write_pos..][0..size], 0);
+        return;
+    }
+    if (block.uncompressed) {
+        @memcpy(map[write_pos..][0..size], self.cache.map.memory[read_offset..][0..size]);
+        return;
+    }
+    const data = self.cache.get(io, read_offset, block.size, size) catch |err| switch (err) {
+        error.Canceled => {
+            io.recancel();
+            return error.Canceled;
+        },
+        else => |e| {
+            ret_err.* = e;
+            return error.Canceled;
+        },
+    };
+    defer self.cache.finished(io, read_offset);
+    if (data.len != size) {
+        std.debug.print("Size of decompression at {} is {} and should be {}\n", .{ read_offset, data.len, size });
+        return Error.BadDecompressionSize;
+    }
+    @memcpy(map[write_pos..][0..size], data);
+}
+fn fragThread(self: Extractor, map: Io.File.MemoryMap) error{Canceled}!void {
+    const write_pos = self.blocks.len * self.block_size;
+    const size = self.size % self.block_size;
+
+    @memcpy(map.memory[write_pos..][0..size], self.frag_data.?[self.frag_offset..][0..size]);
+}
+
+// Types
+
+pub const Error = error{BadDecompressionSize} || Io.File.WritePositionalError || Io.File.MemoryMap.CreateError;