StreamingDecompressor

Process compressed data in chunks for streaming decompression. Defined in src/streaming/decompress.zig:11 and re-exported as zstd.StreamingDecompressor / zstd.DStream (src/zstd.zig:29-31).

Definition

pub const StreamingDecompressor = struct {
    allocator: std.mem.Allocator,
    in_buffer: std.ArrayList(u8),
    out_buffer: std.ArrayList(u8),
    stage: Stage, // .header, .blocks, .checksum, .done
    frame_header: ?FrameHeader,
    checksum_state: ChecksumState,
    finished: bool,
    // ...
};
pub const DStream = StreamingDecompressor;

Methods

init

pub fn init(allocator: std.mem.Allocator) StreamingDecompressor

var dstream = zstd.StreamingDecompressor.init(allocator);
defer dstream.deinit();
// alias
var dstream2 = zstd.DStream.init(allocator);
defer dstream2.deinit();

deinit

pub fn deinit(self: *StreamingDecompressor) void

decompressStream

Incrementally decompress a chunk:

pub fn decompressStream(self: *StreamingDecompressor, out: []u8, in_data: []const u8)
    ZstdError!struct { in_consumed: usize, out_produced: usize, needs_more: bool }

var out: [1 << 16]u8 = undefined;
var out_pos: usize = 0;
var in_pos: usize = 0;
while (in_pos < compressed.len) {
    const chunk = compressed[in_pos..@min(in_pos + 64, compressed.len)];
    const res = try dstream.decompressStream(out[out_pos..], chunk);
    in_pos += res.in_consumed; // equals chunk.len
    out_pos += res.out_produced;
    if (!res.needs_more) break;
}

decompressAll

Convenience: decompress entire buffer via the stream context (delegates to decompressInto):

pub fn decompressAll(self: *StreamingDecompressor, out: []u8, in_data: []const u8) ZstdError!usize

var out: [1 << 16]u8 = undefined;
const n = try dstream.decompressAll(&out, compressed);

reset

Reset for reuse:

pub fn reset(self: *StreamingDecompressor) void

Example

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);
    in_pos += res.in_consumed;
    out_pos += res.out_produced;
}
std.debug.assert(std.mem.eql(u8, original, out[0..out_pos]));

Removed names: old StreamDecompressor.init(allocator, opts), StreamDecompressOptions { dict: ?[]const u8 }, decompressChunk, recommendedDecompressInSize/OutSize no longer exist — use StreamingDecompressor / DStream with decompressStream / decompressAll.