PMM and liballoc port

kernel/libk/bm.c

@@ -0,0 +1,91 @@
+#include <libk/std.h>
+#include <libk/bm.h>
+#include <libk/string.h>
+
+void bm_init(struct bm *bm, uint8_t *base, size_t nbits) {
+  bm->base = base;
+  bm->nbits = nbits;
+  memset(bm->base, 0, (nbits + 7) / 8);
+}
+
+/*
+ * Set a bit in a bitmap.
+ */
+void bm_set(struct bm *bm, size_t k) {
+  if (k >= bm->nbits)
+    return;
+
+  uint8_t *b = (uint8_t *)((uintptr_t)bm->base + (k / 8));
+  *b = ((*b) | (1 << (k % 8)));
+}
+
+/*
+ * Clear a bit in a bitmap.
+ */
+void bm_clear(struct bm *bm, size_t k) {
+  if (k >= bm->nbits)
+    return;
+
+  uint8_t *b = (uint8_t *)((uintptr_t)bm->base + (k / 8));
+  *b = ((*b) & ~(1 << (k % 8)));
+}
+
+/*
+ * Test (true/false) a bit in a bitmap.
+ */
+bool bm_test(struct bm *bm, size_t k) {
+  if (k >= bm->nbits)
+    return false;
+
+  uint8_t *b = (uint8_t *)((uintptr_t)bm->base + (k / 8));
+  return (*b) & (1 << (k % 8));
+}
+
+/*
+ * Set a range of bits in a bitmap. if starting bit is out of range, we fail.
+ */
+bool bm_set_region(struct bm *bm, size_t k, size_t m) {
+  if ((k >= m) || (k >= bm->nbits) || (k + m >= bm->nbits))
+    return false;
+
+  for (size_t i = k; i < m; i++) {
+    bool taken = bm_test(bm, i);
+    if (taken)
+      return false;
+  }
+
+  for (size_t i = k; i < m; i++)
+    bm_set(bm, i);
+  
+  return true;
+}
+
+/*
+ * Clear a range of bits in a bitmap. starting bit must be in range.
+ */
+void bm_clear_region(struct bm *bm, size_t k, size_t m) {
+  if ((k >= m) || (k >= bm->nbits) || (k + m >= bm->nbits))
+    return;
+
+  for (size_t i = k; i < m; i++)
+    bm_clear(bm, i);
+}
+
+/*
+ * Test a range if bits in a bitmap. Return true if at least one bit
+ * is set, else return false (all bits clear). For convenience, if k or m
+ * are out of range, act as if the bits are set / bitmap is full - this is
+ * useful for implementing the physical memory manager algorithm.
+ */
+bool bm_test_region(struct bm *bm, size_t k, size_t m) {
+  if ((k >= m) || (k >= bm->nbits) || (k + m >= bm->nbits))
+    return true;
+
+  for (size_t i = k; i < m; i++) {
+    bool test = bm_test(bm, i);
+    if (test)
+      return true;
+  }
+
+  return false;
+}