Function init [src]

Validates frame_header and returns the associated FrameContext. Errors returned: error.DictionaryIdFlagUnsupported if the frame uses a dictionary error.WindowSizeUnknown if the frame does not have a valid window size error.WindowTooLarge if the window size is larger than window_size_max error.ContentSizeTooLarge if the frame header indicates a content size larger than std.math.maxInt(usize)

Prototype

pub fn init( frame_header: ZstandardHeader, window_size_max: usize, verify_checksum: bool, ) Error!FrameContext

Parameters

frame_header: ZstandardHeaderwindow_size_max: usizeverify_checksum: bool

Possible Errors

ContentSizeTooLarge

DictionaryIdFlagUnsupported

WindowSizeUnknown

WindowTooLarge

Source

  pub fn init(
    frame_header: ZstandardHeader,
    window_size_max: usize,
    verify_checksum: bool,
) Error!FrameContext {
    if (frame_header.descriptor.dictionary_id_flag != 0)
        return error.DictionaryIdFlagUnsupported;

    const window_size_raw = frameWindowSize(frame_header) orelse return error.WindowSizeUnknown;
    const window_size = if (window_size_raw > window_size_max)
        return error.WindowTooLarge
    else
        @as(usize, @intCast(window_size_raw));

    const should_compute_checksum =
        frame_header.descriptor.content_checksum_flag and verify_checksum;

    const content_size = if (frame_header.content_size) |size|
        std.math.cast(usize, size) orelse return error.ContentSizeTooLarge
    else
        null;

    return .{
        .hasher_opt = if (should_compute_checksum) std.hash.XxHash64.init(0) else null,
        .window_size = window_size,
        .has_checksum = frame_header.descriptor.content_checksum_flag,
        .block_size_max = @min(types.block_size_max, window_size),
        .content_size = content_size,
    };
}  