Function fixedLiteralEncoder [src]

Generates a HuffmanCode corresponding to the fixed literal table

Prototype

pub fn fixedLiteralEncoder(codes: *[max_num_frequencies]Code) HuffmanEncoder

Parameters

codes: *[max_num_frequencies]Code

Source

  pub fn fixedLiteralEncoder(codes: *[max_num_frequencies]Code) HuffmanEncoder {
    var h: HuffmanEncoder = undefined;
    h.codes = codes;
    var ch: u16 = 0;

    while (ch < max_num_frequencies) : (ch += 1) {
        var bits: u16 = undefined;
        var size: u16 = undefined;
        switch (ch) {
            0...143 => {
                // size 8, 000110000  .. 10111111
                bits = ch + 48;
                size = 8;
            },
            144...255 => {
                // size 9, 110010000 .. 111111111
                bits = ch + 400 - 144;
                size = 9;
            },
            256...279 => {
                // size 7, 0000000 .. 0010111
                bits = ch - 256;
                size = 7;
            },
            else => {
                // size 8, 11000000 .. 11000111
                bits = ch + 192 - 280;
                size = 8;
            },
        }
        h.codes[ch] = .{ .code = bitReverse(u16, bits, @as(u5, @intCast(size))), .len = size };
    }
    return h;
}  