view src/core/ngx_murmurhash.c @ 8824:81a3429db8b0 quic

HTTP/3: delayed Insert Count Increment instruction. Sending the instruction is delayed until the end of the current event cycle. Delaying the instruction is allowed by quic-qpack-21, section 2.2.2.3. The goal is to reduce the amount of data sent back to client by accumulating several inserts in one instruction and sometimes not sending the instruction at all, if Section Acknowledgement was sent just before it.
author Roman Arutyunyan <arut@nginx.com>
date Thu, 27 Jan 2022 12:20:47 +0300
parents f38647c651a8
children
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/*
 * Copyright (C) Austin Appleby
 */


#include <ngx_config.h>
#include <ngx_core.h>


uint32_t
ngx_murmur_hash2(u_char *data, size_t len)
{
    uint32_t  h, k;

    h = 0 ^ len;

    while (len >= 4) {
        k  = data[0];
        k |= data[1] << 8;
        k |= data[2] << 16;
        k |= data[3] << 24;

        k *= 0x5bd1e995;
        k ^= k >> 24;
        k *= 0x5bd1e995;

        h *= 0x5bd1e995;
        h ^= k;

        data += 4;
        len -= 4;
    }

    switch (len) {
    case 3:
        h ^= data[2] << 16;
        /* fall through */
    case 2:
        h ^= data[1] << 8;
        /* fall through */
    case 1:
        h ^= data[0];
        h *= 0x5bd1e995;
    }

    h ^= h >> 13;
    h *= 0x5bd1e995;
    h ^= h >> 15;

    return h;
}