Joran Dirk Greef jorangreef

Founder & CEO of @tigerbeetle, the distributed financial transactions database for mission critical safety and performance.

kprotty / rANS.zig

Created February 9, 2024 17:52

	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;