catid

/*
  // Convolutional encoder:
  s = a * x + b * y;
  t = c * x + d * y;

  The problem with this one is that the "ezc" number of low bit zeros in e is also a number of additional bits that must be sent with each recovery word.
  Specifically in the decoder this line:
  > uint64_t yr = ei * t >> ezc;

  So to tolerate ezc = 4 zero bits, we need to make t 4 bits longer.

catid

#include <stdint.h>

/*
    65-bit multiplication of two 64-bit values a, b
    with low bits set to 1 (implicitly):

    (2a + 1)(2b + 1)
    = 4ab + 2a + 2b + 1

    Stuffing it back into a 64-bit value:

catid

uint64_t f64(uint64_t x, uint64_t y) {
    return y * (2 - y * x);
}

static uint64_t inverse64(uint64_t x) {
    uint64_t y = x;
    y = f64(x, y);
    y = f64(x, y);
    y = f64(x, y);
    y = f64(x, y);

catid

q = x >> 32
r = x - (q << 32)
i = 0

while (q > 0) {
 t = (q << 4) - q
 q = t >> 32
 r_i = t - (q << 32)
 if (++i % 2 == 1)
  r -= r_i

catid

Spinal Codes (totally metal name)
Paper: http://nms.csail.mit.edu/papers/fp049-perry.pdf

This is a bitwise error correction code that can correct bit errors anywhere in the message.
It is not MDS and the strength of the code includes the processing time allowed for decoding.
More discussion at the end.


Simple version of the algorithm:

catid

//------------------------------------------------------------------------------
// Intrinsics

/// Returns first position with set bit (LSB = 0)
/// Precondition: x != 0
TONK_FORCE_INLINE unsigned NonzeroLowestBitIndex(uint32_t x)
{
#ifdef _MSC_VER
    unsigned long index;
    // Note: Ignoring result because x != 0

catid

{d-Connection} [127.0.0.1:1] Connection::OnTimeSync(ReceivedBPS=105088, LossRate=0)
{d-Connection} [127.0.0.1:1] Connection::OnTimeSync(ReceivedBPS=129088, LossRate=0)
{d-Connection} [127.0.0.1:1] Connection::OnTimeSync(ReceivedBPS=129088, LossRate=0)
{d-Connection} [127.0.0.1:1] Connection::OnTimeSync(ReceivedBPS=113088, LossRate=0.125)
{d-Connection} [127.0.0.1:1] Connection::OnTimeSync(ReceivedBPS=113088, LossRate=0.125)
{d-Connection} [127.0.0.1:1] Connection::OnTimeSync(ReceivedBPS=98944, LossRate=0.230469)

Got router queue filling up simulation working
My crappy current CC increases the send rate to 129KB/S until the queue fills up (filling 1 MB buffer) and data starts dropping off the back
Then CC detects loss and sets send rate lower

catid

    /* Scan input and build symbol stats */
    {  CHECK_V_F(largest, FSE_count_wksp (table->count, &maxSymbolValue, (const BYTE*)src, srcSize, table->count) );
        if (largest == srcSize) { *ostart = ((const BYTE*)src)[0]; return 1; }   /* single symbol, rle */
        if (largest <= (srcSize >> 7) + 1) {
            return 0;   /* heuristic : probably not compressible enough */
        }

        /* Added this more accurate heuristic to handle high entropy data properly -catid */
        U64 total = 0;
        U64 sum_clogc = 0;

catid

#pragma once

#include "xxxxxxxxxProtocol.h"
#include "xxxxxxxxxTools.h"

#define ZSTD_STATIC_LINKING_ONLY /* Enable advanced API */
#include "thirdparty/zstd/zstd.h" // Zstd
#include "thirdparty/zstd/zstd_errors.h"

namespace xxx {

catid

/**
    RoughStrCompare()

    This does a rough ASCII case-insensitive string comparison.  Mainly for fun.
    All of the a-z and A-Z ASCII codes are between 0x41 - 0x5A and 0x61 - 0x7A.
    The idea here is to mask out 0x20 to make these equivalent (case-insensitive)
    but the problem with this idea is that it aliases these characters:
         @ with `    [ with {    \ with |    ] with }    ^ with ~
*/