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/* Copyright 2000-2005 The Apache Software Foundation or its licensors, as
* applicable.
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* The high resolution timer API provides access to the hardware timer
* running at around 1.1MHz. The amount this changes in a time slice is
* varies randomly due to system events, hardware interrupts etc
*/
static UCHAR randbyte_hrtimer()
{
QWORD t1, t2;
UCHAR byte;
DosTmrQueryTime(&t1);
DosSleep(5);
DosTmrQueryTime(&t2);
byte = (t2.ulLo - t1.ulLo) & 0xFF;
byte ^= (t2.ulLo - t1.ulLo) >> 8;
return byte;
}
/* A bunch of system information like memory & process stats.
* Not highly random but every bit helps....
*/
static UCHAR randbyte_sysinfo()
{
UCHAR byte = 0;
UCHAR SysVars[100];
int b;
DosQuerySysInfo(1, QSV_FOREGROUND_PROCESS, SysVars, sizeof(SysVars));
for (b = 0; b < 100; b++) {
byte ^= SysVars[b];
}
return byte;
}
/* Similar in concept to randbyte_hrtimer() but accesses the CPU's internal
* counters which run at the CPU's MHz speed. We get separate
* idle / busy / interrupt cycle counts which should provide very good
* randomness due to interference of hardware events.
* This only works on newer CPUs (at least PPro or K6) and newer OS/2 versions
* which is why it's run-time linked.
*/
static APIRET APIENTRY(*DosPerfSysCall) (ULONG ulCommand, ULONG ulParm1,
ULONG ulParm2, ULONG ulParm3) = NULL;
static HMODULE hDoscalls = 0;
#define CMD_KI_RDCNT (0x63)
typedef struct _CPUUTIL {
ULONG ulTimeLow; /* Low 32 bits of time stamp */
ULONG ulTimeHigh; /* High 32 bits of time stamp */
ULONG ulIdleLow; /* Low 32 bits of idle time */
ULONG ulIdleHigh; /* High 32 bits of idle time */
ULONG ulBusyLow; /* Low 32 bits of busy time */
ULONG ulBusyHigh; /* High 32 bits of busy time */
ULONG ulIntrLow; /* Low 32 bits of interrupt time */
ULONG ulIntrHigh; /* High 32 bits of interrupt time */
} CPUUTIL;
static UCHAR randbyte_perf()
{
UCHAR byte = 0;
CPUUTIL util;
int c;
if (hDoscalls == 0) {
char failed_module[20];
ULONG rc;
rc = DosLoadModule(failed_module, sizeof(failed_module), "DOSCALLS",
&hDoscalls);
if (rc == 0) {
rc = DosQueryProcAddr(hDoscalls, 976, NULL, (PFN *)&DosPerfSysCall);
if (rc) {
DosPerfSysCall = NULL;
}
}
}
if (DosPerfSysCall) {
if (DosPerfSysCall(CMD_KI_RDCNT, (ULONG)&util, 0, 0) == 0) {
for (c = 0; c < sizeof(util); c++) {
byte ^= ((UCHAR *)&util)[c];
}
}
else {
DosPerfSysCall = NULL;
}
}
return byte;
}
static UCHAR randbyte()
{
return randbyte_hrtimer() ^ randbyte_sysinfo() ^ randbyte_perf();
}
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