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#ifndef __ATOMIC_H__
#define __ATOMIC_H__
#include <deque>
#include <Exceptions.h>
namespace Atomic {
#if (__GNUC__ >= 5) || ((__GNUC__ == 4) && ((__GNUC_MINOR__ >= 1)))
// gcc version of the atomic operations
template <class T> T Or(volatile T * ptr, T mask) { __sync_or_and_fetch(ptr, mask); }
template <class T> T And(volatile T * ptr, T mask) { __sync_and_and_fetch(ptr, mask); }
template <class T> T Xor(volatile T * ptr, T mask) { __sync_xor_and_fetch(ptr, mask); }
template <class T> T Nand(volatile T * ptr, T mask) { __sync_nand_and_fetch(ptr, mask); }
template <class T> T Increment(volatile T * ptr, T delta = 1) { __sync_add_and_fetch(ptr, delta); }
template <class T> T Decrement(volatile T * ptr, T delta = 1) { __sync_sub_and_fetch(ptr, delta); }
namespace Prefetch {
template <class T> T Or(volatile T * ptr, T mask) { __sync_fetch_and_or(ptr, mask); }
template <class T> T And(volatile T * ptr, T mask) { __sync_fetch_and_and(ptr, mask); }
template <class T> T Xor(volatile T * ptr, T mask) { __sync_fetch_and_xor(ptr, mask); }
template <class T> T Nand(volatile T * ptr, T mask) { __sync_fetch_and_nand(ptr, mask); }
template <class T> T Increment(volatile T * ptr, T delta = 1) { __sync_fetch_and_add(ptr, delta); }
template <class T> T Decrement(volatile T * ptr, T delta = 1) { __sync_fetch_and_sub(ptr, delta); }
};
template <class T> T CmpXChgVal(volatile T * ptr, const T xch, const T cmp) { return __sync_val_compare_and_swap(ptr, cmp, xch); }
template <class T> bool CmpXChgBool(volatile T * ptr, const T xch, const T cmp) { return __sync_bool_compare_and_swap(ptr, cmp, xch); }
template <class T> T Exchange32(volatile T * ptr, const T exchange) {
#if defined(i386) || defined (__x86_64)
__asm__ __volatile__("lock xchgl %0, (%1)" : "+r"(exchange) : "r"(ptr));
return exchange;
#else
T p;
do { p = *ptr; } while (!__sync_bool_compare_and_swap(ptr, p, exchange));
return p;
#endif
}
template <class T> T Exchange64(volatile T * ptr, const T exchange) {
#if defined(i386) || defined (__x86_64)
__asm__ __volatile__("lock xchgq %0, (%1)" : "+r"(exchange) : "r"(ptr));
return exchange;
#else
T p;
do { p = *ptr; } while (!__sync_bool_compare_and_swap(ptr, p, exchange));
return p;
#endif
}
#else
#ifdef _MSVC
// Visual Studio version of the atomic operations
#error MSVC not yet implemented... and probably never will -.-
#else
#error No known platform for atomic operations.
#endif
#endif
template <class T> T * ExchangePtr(T * volatile * ptr, const T * exchange) {
#if defined (__x86_64)
return Exchange64(ptr, exchange);
#else
return Exchange32(ptr, exchange);
#endif
}
// This is a multiple producers / single consumer queue system. Stolen from the Fugue VM.
template<class T>
class Queue {
private:
struct ptr_t;
struct node_t {
node_t() : next(0), val(0) { }
explicit node_t(T * val) : next(0), val(val) { }
node_t * next;
T * val;
ptr_t * ptr;
};
struct ptr_t {
ptr_t() : next(0), node(0) { }
explicit ptr_t(node_t * node) : next(0), node(node) { }
ptr_t(ptr_t * next, node_t * node) : next(next), node(node) { }
ptr_t * next;
node_t * node;
};
public:
static const int NUMSLOTS = 16384;
Queue() {
unsigned int i;
WHead = OWHead = new node_t;
RHead = ORHead = new node_t;
NodeFreeList = NULL;
for(i = 0; i < NUMSLOTS; i++) {
ptr_t * ptr = new ptr_t(NodeFreeList, &NodeBuffer[i]);
FreeListHead = NodeFreeList = ptr;
NodeBuffer[i].ptr = ptr;
}
}
~Queue() {
unsigned int i;
typename std::deque<node_t *>::iterator itr;
for (itr = PendingReads.begin(); itr != PendingReads.end(); itr++)
delete (*itr)->val;
node_t * n;
n = WHead;
while (n) {
delete n->val;
n = n->next;
}
n = RHead;
while (n) {
delete n->val;
n = n->next;
}
for (i = 0; i < NUMSLOTS; i++)
delete NodeBuffer[i].ptr;
delete ORHead;
delete OWHead;
}
void enqueue(T * val) {
node_t * node = AllocateNode(val);
while (true) {
node->next = WHead;
if (CmpXChgBool(&WHead, node, node->next))
return;
}
}
public:
T * unqueue(T ** pval = 0) {
T * r;
if (!PendingReads.empty()) {
r = PopPendingRead();
if (pval)
*pval = r;
return r;
}
if (!RHead->next)
SwapReadAndWrite();
node_t * n;
n = RHead;
while (RHead->next) {
PendingReads.push_back(n);
n = n->next;
RHead = n;
}
if (PendingReads.empty()) {
if (pval)
*pval = 0;
return 0;
}
r = this->PopPendingRead();
if (pval)
*pval = r;
return r;
}
private:
T * PopPendingRead() {
node_t * node = PendingReads.back();
T * val = node->val;
FreeNode(node);
PendingReads.pop_back();
return val;
}
void SwapReadAndWrite() {
while (true) {
node_t * rh = RHead, * ow = WHead;
if (CmpXChgBool(&WHead, rh, ow)) {
RHead = ow;
return;
}
}
}
node_t * AllocateNode(T * val) throw (GeneralException) {
ptr_t * ptr;
if (!FreeListHead->next)
throw GeneralException("No more free slots in the queue.");
ptr_t * newhead;
do {
ptr = FreeListHead;
newhead = ptr->next;
} while (!CmpXChgBool(&FreeListHead, newhead, ptr));
ptr->node->val = val;
return ptr->node;
}
void FreeNode(node_t * node) {
node->val = 0;
while (true) {
node->ptr->next = FreeListHead;
if (CmpXChgBool(&FreeListHead, node->ptr, node->ptr->next))
break;
}
}
node_t * WHead, * OWHead, * RHead, * ORHead, NodeBuffer[NUMSLOTS];
ptr_t * NodeFreeList, * FreeListHead;
// this should be stored in TLS...
typename std::deque<node_t *> PendingReads;
};
}; // namespace Atomic
#endif
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