rename reverse_bits to bits and move functions to count bits in there

common/utils/bits.h

@@ -0,0 +1,34 @@
+/*
+ * SPDX-License-Identifier: LicenseRef-CSSL-1.0
+ */
+
+#ifndef BITS_H_
+#define BITS_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include "assertions.h"
+
+uint64_t reverse_bits(uint64_t in, int n_bits);
+void reverse_bits_u8(uint8_t const* in, size_t sz, uint8_t* out);
+
+static inline int count_bits(uint8_t *arr, int sz)
+{
+  AssertFatal(sz % sizeof(int) == 0, "to implement if needed\n");
+  int ret = 0;
+  for (uint *ptr = (uint *)arr; (uint8_t *)ptr < arr + sz; ptr++)
+    ret += __builtin_popcount(*ptr);
+  return ret;
+}
+
+static __attribute__((always_inline)) inline int count_bits64(uint64_t v)
+{
+  return __builtin_popcountll(v);
+}
+
+static __attribute__((always_inline)) inline int count_bits64_with_mask(uint64_t v, int start, int num)
+{
+  uint64_t mask = ((1LL << num) - 1) << start;
+  return count_bits64(v & mask);
+}
+#endif /* BITS_H_ */