Streaming Decompression

examples/streaming_decompression.zig — StreamingDecompressor / DStream.

Client Code

const original = "Streaming decompression handles partial input and output buffers with backpressure. " ** 10;
const compressed = try zstd.compress(allocator, original);
defer allocator.free(compressed);

var dstream = zstd.StreamingDecompressor.init(allocator);
defer dstream.deinit();

var out: [1 << 16]u8 = undefined;
var out_pos: usize = 0;
var in_pos: usize = 0;
const chunk_size: usize = 64;
while (in_pos < compressed.len) {
    const chunk = compressed[in_pos..@min(in_pos + chunk_size, compressed.len)];
    const res = try dstream.decompressStream(out[out_pos..], chunk);
    // res = { in_consumed: usize, out_produced: usize, needs_more: bool }
    in_pos += res.in_consumed;
    out_pos += res.out_produced;
    if (res.needs_more and in_pos >= compressed.len) break;
}
std.debug.assert(std.mem.eql(u8, original, out[0..out_pos]));

// Convenience
var dstream2 = zstd.StreamingDecompressor.init(allocator);
defer dstream2.deinit();
var out2: [1 << 16]u8 = undefined;
const n = try dstream2.decompressAll(&out2, compressed);

Output

Stream decompressed 840 bytes
Verified streaming decompression

Explanation

• StreamingDecompressor maintains in_buffer/out_buffer, stage (header → blocks → checksum → done) and frame_header.
• Handles 1-byte chunks, skippable frames, multiple frames, truncated checks, and ChecksumWrong.
• decompressAll is a one-shot helper delegating to decompress/decompress.zig:92.

Run:

zig build run-streaming_decompression