64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
#include <assert.h>
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#include <log.h>
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#include <spinlock.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <sysconfig.h>
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#define FREE_PAGE_MAGIC 0x50474d43
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#define PAGE_MASK (PAGE_SIZE - 1)
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struct free_page {
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uint32_t magic;
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struct free_page *next;
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};
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static uint8_t *pager_next = 0;
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static uint8_t *pager_limit = 0;
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static struct free_page *free_list = 0;
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static uint32_t spinlock = 0;
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void gilbraltar_pager_init(uintptr_t base, size_t size) {
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pager_next = (uint8_t *)((base + PAGE_SIZE - 1) & ~PAGE_MASK);
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pager_limit = (uint8_t *)((base + size) & ~PAGE_MASK);
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}
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size_t gilbraltar_pager_free_space(void) { return (pager_limit - pager_next); }
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void *gilbraltar_palloc(void) {
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assert(pager_next != 0);
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gilbraltar_spinlock_acquire(IRQ, &spinlock);
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gilbraltar_log(DEBUG, "Allocate a new page (actual: %08lx)\r\n",
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(uintptr_t)pager_next);
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struct free_page *free_page;
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if ((free_page = free_list) != 0) {
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assert(free_page->magic == FREE_PAGE_MAGIC);
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free_list = free_page->next;
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free_page->magic = 0;
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} else {
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free_page = (struct free_page *)pager_next;
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pager_next += PAGE_SIZE;
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if (pager_next > pager_limit) {
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gilbraltar_spinlock_release(IRQ, &spinlock);
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gilbraltar_log(ERROR, "Out of page.\r\n");
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abort();
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}
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}
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gilbraltar_log(DEBUG, "New page @ %08lx.\r\n", (uintptr_t)free_page);
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gilbraltar_spinlock_release(IRQ, &spinlock);
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return (free_page);
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}
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void gilbraltar_pager_free(void *page) {
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struct free_page *free_page = (struct free_page *)page;
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gilbraltar_spinlock_acquire(IRQ, &spinlock);
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free_page->magic = FREE_PAGE_MAGIC;
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free_page->next = free_list;
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free_list = free_page;
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gilbraltar_spinlock_release(IRQ, &spinlock);
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}
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