os2rng.c

Netscape NSPR库源码

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is the Netscape Portable Runtime (NSPR).
 * 
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are 
 * Copyright (C) 1999-2000 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s):
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable 
 * instead of those above.  If you wish to allow use of your 
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */


#define INCL_DOS
#define INCL_DOSERRORS
#include <os2.h>
#include <stdlib.h>
#include <time.h>
#include "primpl.h"

static BOOL clockTickTime(unsigned long *phigh, unsigned long *plow)
{
    APIRET rc = NO_ERROR;
    QWORD qword = {0,0};

    rc = DosTmrQueryTime(&qword);
    if (rc != NO_ERROR)
       return FALSE;

    *phigh = qword.ulHi;
    *plow  = qword.ulLo;

    return TRUE;
}

extern PRSize _PR_MD_GetRandomNoise(void *buf, PRSize size )
{
    unsigned long high = 0;
    unsigned long low  = 0;
    clock_t val = 0;
    int n = 0;
    int nBytes = 0;
    time_t sTime;

    if (size <= 0)
       return 0;

    clockTickTime(&high, &low);

    /* get the maximally changing bits first */
    nBytes = sizeof(low) > size ? size : sizeof(low);
    memcpy(buf, &low, nBytes);
    n += nBytes;
    size -= nBytes;

    if (size <= 0)
       return n;

    nBytes = sizeof(high) > size ? size : sizeof(high);
    memcpy(((char *)buf) + n, &high, nBytes);
    n += nBytes;
    size -= nBytes;

    if (size <= 0)
       return n;

    /* get the number of milliseconds that have elapsed since application started */
    val = clock();

    nBytes = sizeof(val) > size ? size : sizeof(val);
    memcpy(((char *)buf) + n, &val, nBytes);
    n += nBytes;
    size -= nBytes;

    if (size <= 0)
       return n;

    /* get the time in seconds since midnight Jan 1, 1970 */
    time(&sTime);
    nBytes = sizeof(sTime) > size ? size : sizeof(sTime);
    memcpy(((char *)buf) + n, &sTime, nBytes);
    n += nBytes;

    return n;
}