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SyncChecker.h
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102 lines (89 loc) · 2.56 KB
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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#ifndef SYNCCHECKER_H
#define SYNCCHECKER_H
#ifdef SYNCCHECK
#ifdef TRACE_SYNC_HEAVY
#include "HsiehHash.h"
#endif
#include <assert.h>
/**
* @brief sync checker class
*
* A Lightweight sync debugger that just keeps a running checksum over all
* assignments to synced variables.
*/
class CSyncChecker {
public:
/**
* Whether one thread (doesn't have to be the current thread!!!) is currently processing a SimFrame.
*/
static bool InSyncedCode() { return (inSyncedCode > 0); }
static void EnterSyncedCode() { ++inSyncedCode; }
static void LeaveSyncedCode() { assert(InSyncedCode()); --inSyncedCode; }
/**
* Keeps a running checksum over all assignments to synced variables.
*/
static unsigned GetChecksum() { return g_checksum; }
static void NewFrame() { g_checksum = 0xfade1eaf; }
static void Sync(const void* p, unsigned size) {
// most common cases first, make it easy for compiler to optimize for it
// simple xor is not enough to detect multiple zeroes, e.g.
#ifdef TRACE_SYNC_HEAVY
g_checksum = HsiehHash((const char*)p, size, g_checksum);
#else
switch(size) {
case 1:
g_checksum += *(const unsigned char*)p;
g_checksum ^= g_checksum << 10;
g_checksum += g_checksum >> 1;
break;
case 2:
g_checksum += *(const unsigned short*)(const char*)p;
g_checksum ^= g_checksum << 11;
g_checksum += g_checksum >> 17;
break;
case 3:
// just here to make the switch statements contiguous (so it can be optimized)
for (unsigned i = 0; i < 3; ++i) {
g_checksum += *(const unsigned char*)p + i;
g_checksum ^= g_checksum << 10;
g_checksum += g_checksum >> 1;
}
break;
case 4:
g_checksum += *(const unsigned int*)(const char*)p;
g_checksum ^= g_checksum << 16;
g_checksum += g_checksum >> 11;
break;
default:
{
unsigned i = 0;
for (; i < (size & ~3) / 4; ++i) {
g_checksum += *(reinterpret_cast<const unsigned int*>(p) + i);
g_checksum ^= g_checksum << 16;
g_checksum += g_checksum >> 11;
}
for (; i < size; ++i) {
g_checksum += *(const unsigned char*)p + i;
g_checksum ^= g_checksum << 10;
g_checksum += g_checksum >> 1;
}
break;
}
}
#endif
}
private:
/**
* The sync checksum
*/
static unsigned g_checksum;
/**
* @brief in synced code
*
* Whether one thread (doesn't have to current thread!!!) is currently processing a SimFrame.
*/
static int inSyncedCode;
};
#endif // SYNCDEBUG
#endif // SYNCDEBUGGER_H