Some unfinished changes + TODO chnages

kernel/src/pmm.c

@@ -1,4 +1,94 @@
+#include <multiboot.h>
+#include <kernel.h>
 #include <pmm.h>
 
-int pmm_init() { return 0; }
+// Helpers
+#define SET_BLOCK(_b)	memmap[(_b) / 32] |= (1 << ((_b) % 32))
+#define USET_BLOCK(_b)	memmap[(_b) / 32] &= ~(1 << ((_b) % 32))
+#define TEST_BLOCK(_b)	((memmap[(_b) % 32] & (1 << ((_b) % 32))) ? 1 : 0)
+
+// Memory manager bitmap
+uint32_t* memmap = NULL;
+size_t usedBlocks = 0;
+size_t maxBlocks = 0;
+
+// TODO: improve these hardcoded values
+int pmm_init(void) {
+	memmap = NULL;	// Memory map location
+	usedBlocks = 0;
+	maxBlocks = 0; // TODO
+	return 0;
+}
+
+int findFreeBlocks(size_t blockCount) {
+	if (blockCount == 0) return -1;
+	
+	uint32_t max = maxBlocks / 32;
+	uint32_t freeCount = 0;
+	for (size_t i = 0; i < max; i++) {
+		// We don't have to check, cause it's all reserved
+		if (memmap[i] == 0xffffffff) continue;
+
+		for (uint8_t j = 0; j < 32; j++) {
+			if (TEST_BLOCK(i * PMM_BPB + j)) freeCount++;
+			else freeCount = 0;
+
+			if (freeCount >= blockCount) return i * PMM_BPB + j;
+		}
+	}
+
+	// We didn't find enough free memory :(
+	return -1;
+}
+
+void pmm_initRegion(size_t base, size_t len) {
+	uint32_t align = base / PMM_BS;
+	uint32_t blockCount = len / PMM_BS;
+
+	while (blockCount-- > 0) {
+		USET_BLOCK(align);
+		align++;
+		usedBlocks--;
+	}
+
+	SET_BLOCK(0);
+}
+
+void pmm_deinitRegion(size_t base, size_t len) {
+	uint32_t align = base / PMM_BS;
+	uint32_t blockCount = len / PMM_BS;
+
+	while (blockCount-- > 0) {
+		align++;
+		SET_BLOCK(align); // We can't increment here, because macros -_(._.)_-
+		usedBlocks++;
+	}
+
+	SET_BLOCK(0);
+}
+
+void* pmm_alloc(size_t blockCount) {
+	if ((maxBlocks - usedBlocks) < blockCount) return NULL;
+
+	int startBlock = findFreeBlocks(blockCount);
+	if (startBlock == -1) return NULL;
+
+	for (size_t i = 0; i < blockCount; i++) {
+		SET_BLOCK(startBlock + i);
+		usedBlocks++;
+	}
+
+	return (void*)(startBlock * PMM_BS);
+}
+
+void pmm_free(void* ptr, size_t blockCount) {
+	size_t startBlock = (size_t)ptr / PMM_BS;
+
+	for (size_t i = 0; i < blockCount; i++) {
+		USET_BLOCK(startBlock + i);
+		usedBlocks--;
+	}
+
+	SET_BLOCK(0);	// Make sure block 0 is always set
+}