things!

2026-09-11 02:21:21 +03:00
parent 2e890fb5b7
commit adfae10938
17 changed files with 949 additions and 119 deletions
@@ -0,0 +1,30 @@
+#ifndef COM_BITS_H
+#define COM_BITS_H
+
+#include "def.h"
+#include <assert.h>
+#include <stdint.h>
+
+/* How many bits needed to represent a given number */
+/* Alternitive semntic: nearest upper power of two */
+static inline int com_bits_needed(uint32_t v) {
+#ifdef COM_DEF_COMPILE_MODERN
+  /* Use intrinsic, required for fast sqrt impl */
+  return v == 0 ? 1 : 32 - __builtin_clz(v);
+#else
+#endif
+  if (v == 0)
+    return 1;
+
+  v--;
+  v |= v >> 1;
+  v |= v >> 2;
+  v |= v >> 4;
+  v |= v >> 8;
+  v |= v >> 16;
+  v++;
+
+  return v;
+}
+
+#endif