kprotty

const M = 12; // Probability scale for rANS state. Symbol frequencies in this log range. Usually 8-12.
const L = 23; // Renormalization factor to control dumping rANS state to bitstream. From rans_byte.h.
const m_min = 8 - 2 - (std.math.divCeil(u32, M, 4) catch unreachable); // Small-size-opt limit when compressing frequencies.
const m_max = [_]u16{m_min, m_min+16, m_min+16+256, m_min+16+256+4096, 1<<M}; // Size ranges for frequencies after small size limit.

fn compress(dst: anytype, src: []const u8) !void {
    // Histogram for the frequency of each byte in input.
    var hist = [_]u32{0} ** 256;
    for (src) |byte| hist[byte] += 1;