feat: extend ata with Bitmap

include/bmp.h

@@ -0,0 +1,37 @@
+#ifndef FROSTBYTE_BMP_H
+#define FROSTBYTE_BMP_H
+
+#include "types.h"
+
+/*
+ * Bitmap: general-purpose fixed-size bitmap over caller-supplied 64-bit
+ * word storage. No heap dependency (the pmm frame allocator uses its own
+ * private copy of this same idea and predates this generic version; this
+ * one is for any other subsystem that needs a bit-indexed set).
+ */
+
+typedef struct Bitmap {
+    uint64* words;
+    usize bitCount;
+} Bitmap;
+
+/* backingWords must hold at least (bitCount + 63) / 64 uint64 words. */
+void bmpInit(Bitmap* b, uint64* backingWords, usize bitCount);
+
+void bmpSet(Bitmap* b, usize index);
+void bmpClear(Bitmap* b, usize index);
+bool bmpTest(const Bitmap* b, usize index);
+
+void bmpSetRange(Bitmap* b, usize start, usize count);
+void bmpClearRange(Bitmap* b, usize start, usize count);
+
+void bmpSetAll(Bitmap* b);
+void bmpClearAll(Bitmap* b);
+
+usize bmpCountSet(const Bitmap* b);
+
+/* Returns the index of the first clear/set bit, or -1 if none exists. */
+isize bmpFindFirstClear(const Bitmap* b);
+isize bmpFindFirstSet(const Bitmap* b);
+
+#endif