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#include "PageAlloc.ns.h"
#include <MemoryManager/PhysMem.ns.h>
#define CACHED_PAGES 3
// This mechanism is supposed to make it impossible to run out of free pages to use as a page table
namespace PageAlloc {
void* freePage[CACHED_PAGES];
int freec = 0;
bool usable = false, locked = false;
void init() {
freec = CACHED_PAGES;
for (u32int i = 0; i < CACHED_PAGES; i++) {
freePage[i] = Mem::kalloc(0x1000, true);
}
usable = true;
}
void* alloc(u32int* phys) {
if (!usable) init();
while (freec < CACHED_PAGES && (!locked)) {
locked = true;
void* next = 0;
if (!Mem::pagingEnabled) {
next = Mem::kalloc(0x1000, true);
} else {
u32int i = 0xFFFFF000;
page_t *p;
while (1) {
p = kernelPageDirectory->getPage(i, true);
if (p->frame == 0) break;
i -= 0x1000;
}
PhysMem::allocFrame(p, true, false);
next = (void*)i;
}
freePage[freec] = next;
freec++;
locked = false;
}
freec--;
void* ret = freePage[freec];
if (!Mem::pagingEnabled) {
*phys = (u32int)ret - 0xC0000000;
} else {
page_t* p = kernelPageDirectory->getPage((u32int)ret, false);
if (p == 0) { //THIS SHOULD NEVER HAPPEN
PANIC("Cached free page does not exist.");
} else if (p->frame == 0) {
PhysMem::allocFrame(p, true, false);
} else {
*phys = (p->frame * 0x1000);
}
}
return ret;
}
void free(void *ptr) {
kernelPageDirectory->freeFrame((u32int)ptr);
return;
}
}
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