Merge of r4778, r4782, r4783, r4824, r4830, r4834: minor fixes. *) Reorder checks in ngx_shared_memory_add() for more consistent error messages. *) Added "const" to ngx_memcpy() with NGX_MEMCPY_LIMIT defined. This fixes warning produced during compilation of the ngx_http_geoip_module due to const qualifier being discarded. *) Fixed possible use of old cached times if runtime went backwards. If ngx_time_sigsafe_update() updated only ngx_cached_err_log_time, and then clock was adjusted backwards, the cached_time[slot].sec might accidentally match current seconds on next ngx_time_update() call, resulting in various cached times not being updated. Fix is to clear the cached_time[slot].sec to explicitly mark cached times are stale and need updating. *) Radix tree preallocation fix. The preallocation size was calculated incorrectly and was always 8 due to sizeof(ngx_radix_tree_t) accidentally used instead of sizeof(ngx_radix_node_t). *) Fixed overflow if ngx_slab_alloc() is called with very big "size" argument. *) Write filter: replaced unneeded loop with one to free chains. Noted by Gabor Lekeny.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_CRC_H_INCLUDED_
#define _NGX_CRC_H_INCLUDED_


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


/* 32-bit crc16 */

static ngx_inline uint32_t
ngx_crc(u_char *data, size_t len)
{
    uint32_t  sum;

    for (sum = 0; len; len--) {

        /*
         * gcc 2.95.2 x86 and icc 7.1.006 compile
         * that operator into the single "rol" opcode,
         * msvc 6.0sp2 compiles it into four opcodes.
         */
        sum = sum >> 1 | sum << 31;

        sum += *data++;
    }

    return sum;
}


#endif /* _NGX_CRC_H_INCLUDED_ */