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#include <cpu.h>
#include <util/mutex.h>
#include <util/lock.h>
#include <globals.h>
void mutex_init(void)
{
for (unsigned long m = 0; m < MAX_MUTEXS; m++) {
mutexs[m].pid = 0;
mutexs[m].addr = 0;
mutex_entries[m].value = &mutexs[m];
mutex_entries[m].entry_type = VALUE_ENTRY;
mutex_entries[m].next = &mutex_entries[(m+1)%MAX_MUTEXS];
}
// Initialize Free Mutexs
mutex_manager.free.start.value = 0;
mutex_manager.free.start.next = &mutex_entries[0];
mutex_manager.free.start.entry_type = START_ENTRY;
mutex_manager.free.end.value = 0;
mutex_manager.free.end.next = &mutex_entries[MAX_MUTEXS-1];
mutex_entries[MAX_MUTEXS-1].next = &mutex_manager.free.end;
mutex_manager.free.end.entry_type = END_ENTRY;
// Initialize In-use Mutexs
mutex_manager.used.start.value = 0;
mutex_manager.used.start.next = &mutex_manager.used.end;
mutex_manager.used.start.entry_type = START_ENTRY;
mutex_manager.used.end.value = 0;
mutex_manager.used.end.next = &mutex_manager.used.start;
mutex_manager.used.end.entry_type = END_ENTRY;
}
struct Mutex* create_mutex(void* addr)
{
struct Entry* e = pop_from_queue(&mutex_manager.free);
if (e == 0)
return 0;
struct Mutex* m = e->value;
m->pid = 0;
m->addr = addr;
push_to_queue(e, &mutex_manager.used);
return e->value;
}
unsigned char delete_mutex(struct Mutex* m)
{
struct Entry* entry = find_value(m, &mutex_manager.used);
if (entry == 0)
return 1;
// Remove it from the queue
remove_next_from_queue(entry);
// Add it to the free queue
prepend_to_queue(entry, &mutex_manager.free);
return 0;
}
void lock_mutex(struct Mutex* m)
{
struct Thread* rthread = scheduler.rthread;
unsigned long rpid = rthread->pid;
unsigned long mode = getmode() & 0x1F;
if (mode == 0x10) {
sys1(SYS_LOCK, m);
// Find this mutex
struct Entry* mentry = find_value(m, &mutex_manager.used);
// If it is not a managed mutex, break away
if (mentry == 0)
return;
// Get the next entry
mentry = mentry->next->next;
// Ensure this thread locks all mutexs sequentially
// To avoid a deadlock
while (mentry->entry_type == VALUE_ENTRY) {
struct Mutex* vmutex = mentry->value;
// If this thread had locked it
// Toggle the lock to prevent deadlock
if (vmutex->pid == rpid) {
sys1(SYS_UNLOCK, m);
sys1(SYS_LOCK, m);
}
mentry = mentry->next;
}
}
}
void unlock_mutex(struct Mutex* m)
{
unlock((struct Lock*)m);
}
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