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#include <kernel/pmem.h>
#include <kernel/asm.h>
#include <kernel/panic.h>
#include <kernel/paging.h>
#include <kernel/string.h>
static struct pfa_zone bios_area;
static struct pfa_zone himem;
int pfa_init(struct mboot_info *header) {
bios_area.start = 0;
bios_area.size = 0;
bios_area.freelist = NULL;
himem.start = HIMEM_START;
himem.size = 0;
himem.freelist = NULL;
struct mboot_mmap_entry *mme = (struct mboot_mmap_entry*)(header->mmap_addr);
map_page(NULL, (uintptr_t)mme, (uintptr_t)mme, PD_PRES);
while ((uintptr_t)mme < (header->mmap_addr + header->mmap_length)) {
if (mme->addr_low >= KSTART && mme->addr_low <= KEND)
continue;
if (mme->type == MBOOT_MEM_AVAILABLE) {
if (mme->addr_low < HIMEM_START)
pfa_free_range(&bios_area, (uintptr_t)mme->addr_low, (uintptr_t)(mme->addr_low+mme->len_low));
else
pfa_free_range(&himem, (uintptr_t)mme->addr_low, (uintptr_t)(mme->addr_low+mme->len_low));
}
unmap_page(NULL, (uintptr_t)mme);
mme += sizeof(struct mboot_mmap_entry);
map_page(NULL, (uintptr_t)mme, (uintptr_t)mme, PD_PRES);
}
unmap_page(NULL, (uintptr_t)mme);
return 0;
}
uintptr_t pfa_alloc(void) {
struct pfa_page *temp = bios_area.freelist;
map_page(NULL, (uintptr_t)temp, (uintptr_t)temp, PD_RW | PD_PRES);
if (temp == NULL)
return PFA_ALLOC_ERR;
bios_area.freelist = temp->next;
memset(temp, PFA_BLOCK_ALLOC, 32);
unmap_page(NULL, (uintptr_t)temp);
return (uintptr_t)temp;
}
void pfa_free(struct pfa_zone *zone, uintptr_t paddr) {
if (paddr % PAGE_SIZE != 0)
panic("Task attempted to free non-aligned memory");
if (paddr >= KSTART && paddr < KEND)
panic("Task attempted to free kernel memory");
map_page(NULL, paddr, paddr, PD_PRES | PD_RW);
memset((void*)paddr, PFA_BLOCK_FREE, 32);
struct pfa_page *temp = (struct pfa_page*)paddr;
temp->next = zone->freelist;
zone->freelist = temp;
unmap_page(NULL, paddr);
zone->size += PAGE_SIZE;
}
void pfa_free_range(struct pfa_zone *zone, uintptr_t pstart, uintptr_t pend) {
uintptr_t p = PGROUNDUP(pstart);
while (p <= pend) {
pfa_free(zone, p);
p += PAGE_SIZE;
}
}
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