Strategy & Compression Levels

There is no CLevel enum — compression levels are plain i32.

Levels

Levels are i32 in range c_level_min = -131072 to c_level_max = 22, with c_level_default = 3 (src/common/constants.zig:23-25). Helpers in src/zstd.zig:142-151:

pub fn minCLevel() i32     // -131072
pub fn maxCLevel() i32     // 22
pub fn defaultCLevel() i32 // 3
pub fn versionString() []const u8 // "1.6.0"
pub fn versionNumber() u32        // 10600

Use with zstd.compressWithLevel or CompressionContext.initWithLevel:

// Numeric levels
const c1 = try zstd.compressWithLevel(allocator, data, 1);  // fast
const c2 = try zstd.compressWithLevel(allocator, data, 3);  // default
const c3 = try zstd.compressWithLevel(allocator, data, 19); // best

// With context
var cctx = zstd.CompressionContext.initWithLevel(allocator, 12);
defer cctx.deinit();
cctx.setLevel(6);

// Via options
const opts = zstd.CompressionOptions{ .level = 9 };
const c4 = try zstd.compressWithOptions(allocator, data, opts);

// Tuned via getCompressionParameters
var tuned = zstd.getCompressionParameters(12, data.len, 20);

Strategy

Strategy is defined in src/common/constants.zig:98 and re-exported as zstd.Strategy (src/zstd.zig:37):

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

Set via CompressionOptions.strategy:

const opts = zstd.CompressionOptions{
    .level = 12,
    .strategy = .btopt,
    .window_log = 20,
};
const compressed = try zstd.compressWithOptions(allocator, data, opts);

Available strategies:

Strategy	Value	Description
.fast	1	Fast mode
.dfast	2	Double-fast
.greedy	3	Greedy
.lazy	4	Lazy
.lazy2	5	Lazy2
.btlazy2	6	BT + Lazy2
.btopt	7	BT Opt
.btultra	8	BT Ultra
.btultra2	9	BT Ultra2

Removed Old API

Old (removed)	New
CLevel enum (fastest=1, default=3, best=19, @enumFromInt)	i32 + minCLevel()/maxCLevel()/defaultCLevel()
CLevel.toInt() / CLevel.fromInt()	plain i32
CompressOptions { level: CLevel }	CompressionOptions { level: i32 }