Source
pub fn readHeader(reader: *Reader, options: Options) !Params {
var props = try reader.takeByte();
if (props >= 225) return error.CorruptInput;
const lc: u4 = @intCast(props % 9);
props /= 9;
const lp: u3 = @intCast(props % 5);
props /= 5;
const pb: u3 = @intCast(props);
const dict_size_provided = try reader.takeInt(u32, .little);
const dict_size = @max(0x1000, dict_size_provided);
const unpacked_size = switch (options.unpacked_size) {
.read_from_header => blk: {
const unpacked_size_provided = try reader.takeInt(u64, .little);
const marker_mandatory = unpacked_size_provided == 0xFFFF_FFFF_FFFF_FFFF;
break :blk if (marker_mandatory) null else unpacked_size_provided;
},
.read_header_but_use_provided => |x| blk: {
_ = try reader.takeInt(u64, .little);
break :blk x;
},
.use_provided => |x| x,
};
return .{
.properties = .{ .lc = lc, .lp = lp, .pb = pb },
.dict_size = dict_size,
.unpacked_size = unpacked_size,
};
}