Spec conformance: zstd.zig implements the Zstandard 1.6.0 specification natively in Zig - every algorithm, frame element, and default table in this document follows that version.

DecompressionContext

A reusable decompression context for decompressing multiple buffers. Re-exported as zstd.DecompressionContext.

Definition

pub const DecompressionContext = struct {
    allocator: std.mem.Allocator,
    stream: StreamingDecompressor,
    maxWindowSize: usize, // default 1<<27
    // ...
};

Methods

init

Create a new decompressor (no options struct):

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

var dctx = zstd.DecompressionContext.init(allocator);
defer dctx.deinit();

deinit

Release streaming buffers:

pub fn deinit(self: *DecompressionContext) void

decompress

Decompress into preallocated buffer:

pub fn decompress(self: *DecompressionContext, dst: []u8, src: []const u8) !usize

var out: [4096]u8 = undefined;
const n = try dctx.decompress(&out, compressed);

decompressAlloc

Decompress with allocator:

pub fn decompressAlloc(self: *DecompressionContext, src: []const u8) anyerror![]u8

const decompressed = try dctx.decompressAlloc(compressed);
defer allocator.free(decompressed);

setMaxWindowSize

Set window size limit:

pub fn setMaxWindowSize(self: *DecompressionContext, size: usize) void

dctx.setMaxWindowSize(1 << 27);

reset

Reset internal stream state:

pub fn reset(self: *DecompressionContext) void

Example

var dctx = zstd.DecompressionContext.init(allocator);
defer dctx.deinit();

dctx.setMaxWindowSize(1 << 26);

// Decompress multiple buffers
const d1 = try dctx.decompressAlloc(c1);
defer allocator.free(d1);

var buf: [4096]u8 = undefined;
const n = try dctx.decompress(&buf, c2);

dctx.reset();

Decoder

zstd.Decoder is a high-level client-side decompression abstraction that accepts DecompressionOptions (safety window limit, checksum policies, dictionary binding) and provides clean buffer and allocation decompression:

pub const Decoder = struct {
    pub fn init(allocator: std.mem.Allocator, options: DecompressionOptions) Decoder;
    pub fn deinit(self: *Decoder) void;
    pub fn reset(self: *Decoder) void;
    pub fn setMaxWindowSize(self: *Decoder, size: usize) void;
    pub fn setDictionary(self: *Decoder, dict: ?*const Dictionary) void;
    pub fn decompress(self: *Decoder, dst: []u8, src: []const u8) !usize;
    pub fn decompressAlloc(self: *Decoder, src: []const u8) anyerror![]u8;
};

Usage

var decoder = zstd.Decoder.init(allocator, .{
    .maxWindowSize = 1 << 27,
    .forceIgnoreChecksum = false,
});
defer decoder.deinit();

const decompressed = try decoder.decompressAlloc(compressed_bytes);
defer allocator.free(decompressed);

Decompressor

zstd.Decompressor is a direct alias for zstd.DecompressionContext matching client naming conventions.