Caleb Gardner
74 lines
2.1 KiB
Zig
74 lines
2.1 KiB
Zig
const std = @import("std");
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const Reader = std.Io.Reader;
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const zstd = std.compress.zstd;
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const Node = std.SinglyLinkedList.Node;
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const Decompressor = @import("../util/decompressor.zig");
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const Error = Decompressor.Error;
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const Self = @This();
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const Buffer = struct {
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node: Node,
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buf: []u8,
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};
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interface: Decompressor = .{ .decomp_fn = decomp },
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alloc: std.mem.Allocator,
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block_size: u32,
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buffers: std.ArrayList(Buffer),
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buffer_queue: std.SinglyLinkedList,
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pub fn init(alloc: std.mem.Allocator, block_size: u32) !Self {
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return .{
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.alloc = alloc,
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.block_size = block_size,
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.buffers = try .initCapacity(alloc, 5),
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};
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}
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pub fn deinit(self: Self) void {
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for (self.buffers) |buf|
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self.alloc.free(buf);
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self.buffers.deinit(self.alloc);
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}
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fn decomp(d: ?*const Decompressor, alloc: std.mem.Allocator, in: []u8, out: []u8) Error!usize {
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if (d == null) {
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const buf = try alloc.alloc(u8, in.len * 2);
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defer alloc.free(buf);
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return zstdDecomp(buf, in, out);
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}
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var self: Self = @fieldParentPtr("interface", d.?);
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const buf_node = self.buffer_queue.popFirst();
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var buf: *Buffer = undefined;
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if (buf_node == null) {
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const new_buf = try self.buffers.addOne(self.alloc);
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new_buf.* = .{ .{}, try self.alloc.alloc(u8, self.block_size + zstd.block_size_max) };
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buf = new_buf;
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} else {
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buf = @fieldParentPtr("node", buf_node);
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}
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defer self.buffer_queue.prepend(&buf.node);
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return zstdDecomp(buf.buf, in, out);
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}
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inline fn zstdDecomp(buffer: []u8, in: []u8, out: []u8) !usize {
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var rdr: Reader = .fixed(in);
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var d = zstd.Decompress.init(&rdr, buffer, .{ .window_len = @truncate(in.len) });
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return d.reader.readSliceShort(out);
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}
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// Stateless
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pub const stateless_decompressor: Decompressor = .{ .decomp_fn = statelessDecomp };
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fn statelessDecomp(_: ?*const Decompressor, alloc: std.mem.Allocator, in: []u8, out: []u8) Error!usize {
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const buf = try alloc.alloc(u8, in.len + zstd.block_size_max);
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defer alloc.free(buf);
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return zstdDecomp(buf, in, out);
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}
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