Added bitmap_t type and bmap_* functions & used them in PMM

kernel/src/bitmap.c

@@ -0,0 +1,47 @@
+#include <kernel.h>
+#include <string.h>
+
+#include <bitmap.h>
+
+void bmap_set(bitmap_t* map, size_t bit, int val) {
+	uint32_t* p = (uint32_t*)map->map;
+	if (val) p[bit / 32] |= (1 << (bit % 32));
+	else p[bit / 32] &= ~(1 << (bit % 32));
+}
+
+int bmap_get(bitmap_t* map, size_t bit) {
+	uint32_t* p = (uint32_t*)map->map;
+	return (p[bit / 32] & (1 << (bit % 32))) ? 1 : 0; 
+}
+
+void bmap_setarea(bitmap_t* map, size_t base, size_t len, int val) {
+	uint32_t align = base / BLOCK_SIZE;
+	uint32_t count = len / BLOCK_SIZE;
+
+	while (count-- > 0) {
+		bmap_set(map, align++, val);
+		map->used += (val) ? 1 : -1;
+	}
+}
+
+void bmap_setall(bitmap_t* map, int val) {
+	uint8_t b = (val) ? 0xff : 0;
+	memset(map->map, b, map->bytes);
+	if (val) map->used = map->blocks;
+	else map->used = 0;
+}
+
+size_t bmap_findarea(bitmap_t* map, size_t len, int val) {
+	if (len == 0) return BMAP_NOT_FOUND;
+
+	uint32_t found = 0;
+	for (size_t i = 0; i < map->blocks; i++) {
+		if (bmap_get(map, i) == val) found++;
+		else found = 0;
+
+		if (found >= len) return i - found;
+	}
+
+	return BMAP_NOT_FOUND;
+}
+