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.

CompressionOptions

Options for zstd.compressWithOptions and StreamingCompressor.initWithOptions, re-exported as zstd.CompressionOptions.

Definition

pub const CompressionOptions = struct {
    level: i32 = 3,
    windowLog: u8 = 0,
    hashLog: u8 = 0,
    chainLog: u8 = 0,
    searchLog: u8 = 0,
    minMatch: u8 = 0,
    targetLength: u32 = 0,
    strategy: Strategy = .fast,
    checksum: bool = false,
    dictId: u32 = 0,
    dictionary: ?*const Dictionary = null,
    contentSize: ?u64 = null,

};

pub const Strategy = enum(u8) {
    fast = 1, dfast = 2, greedy = 3, lazy = 4, lazy2 = 5, btlazy2 = 6, btopt = 7, btultra = 8, btultra2 = 9,
};

Fields

Field	Type	Default	Description
level	i32	3	Compression level (-131072..22; defaultCLevel()=3). Used by getCompressionParameters to derive other params
windowLog	u8	0	Window log override (0 = auto, otherwise 10..31)
hashLog	u8	0	Hash table log size override
chainLog	u8	0	Chain log size override
searchLog	u8	0	Search log size override
minMatch	u8	0	Minimum match length (3..7)
targetLength	u32	0	Target length (0..131072)
strategy	Strategy	.fast	Compression strategy
checksum	bool	false	Enable XXH64 frame checksum (checksumFlag in header)
dictId	u32	0	Dictionary ID written to frame header
contentSize	?u64	null	Pledged source size (null = auto from src.len)

Usage

const zstd = @import("zstd");

// Default options via compress()
const c1 = try zstd.compress(allocator, data);

// With explicit level
const c2 = try zstd.compressWithLevel(allocator, data, 9);

// With CompressionOptions
const c3 = try zstd.compressWithOptions(allocator, data, .{
    .level = 9,
    .checksum = true,
});

// All options + strategy
const c4 = try zstd.compressWithOptions(allocator, data, .{
    .level = 12,
    .windowLog = 22,
    .hashLog = 18,
    .chainLog = 18,
    .searchLog = 6,
    .minMatch = 4,
    .targetLength = 32,
    .strategy = .btopt,
    .checksum = true,
    .dictId = 42,
    .contentSize = @as(?u64, data.len),

});

// Derive tuned options then tweak
var tuned = zstd.getCompressionParameters(12, data.len, 20);
tuned.checksum = true;
const c5 = try zstd.compressWithOptions(allocator, data, tuned);