1 files changed, 71 insertions, 0 deletions
diff --git a/arch/i386/kernel/pmem.c b/arch/i386/kernel/pmem.c
new file mode 100644
index 0000000..851b085
--- /dev/null
+++ b/arch/i386/kernel/pmem.c
@@ -0,0 +1,71 @@
+#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;
+        }
+}