bitops: new module.

[ccan] / ccan / bitops / bitops.c

diff --git a/ccan/bitops/bitops.c b/ccan/bitops/bitops.c
new file mode 100644 (file)
index 0000000..fef857a
--- /dev/null
+++ b/ccan/bitops/bitops.c
@@ -0,0 +1,79 @@
+/* CC0 license (public domain) - see LICENSE file for details */
+#include <ccan/bitops/bitops.h>
+#include <stdlib.h>
+
+/* We do naive replacement versions: good for testing, and really your
+ * compiler should do better. */
+#ifdef BITOPS_NEED_FFS
+int bitops_ffs32(uint32_t u)
+{
+       int i;
+       for (i = 0; i < 32; i++)
+               if (u & ((uint32_t)1 << i))
+                       return i + 1;
+       return 0;
+}
+
+int bitops_ffs64(uint64_t u)
+{
+       int i;
+       for (i = 0; i < 64; i++)
+               if (u & ((uint64_t)1 << i))
+                       return i + 1;
+       return 0;
+}
+#endif
+
+#ifdef BITOPS_NEED_CLZ
+int bitops_clz32(uint32_t u)
+{
+       int i;
+       for (i = 0; i < 32; i++)
+               if (u & ((uint32_t)1 << (31 - i)))
+                       return i;
+       abort();
+}
+
+int bitops_clz64(uint64_t u)
+{
+       int i;
+       for (i = 0; i < 64; i++)
+               if (u & ((uint64_t)1 << (63 - i)))
+                       return i;
+       abort();
+}
+#endif
+
+#ifdef BITOPS_NEED_CTZ
+int bitops_ctz32(uint32_t u)
+{
+       BITOPS_ASSERT_NONZERO(u);
+       return bitops_ffs32(u) - 1;
+}
+
+int bitops_ctz64(uint64_t u)
+{
+       BITOPS_ASSERT_NONZERO(u);
+       return bitops_ffs64(u) - 1;
+}
+#endif
+
+#ifdef BITOPS_NEED_WEIGHT
+int bitops_weight32(uint32_t u)
+{
+       int i, num = 0;
+       for (i = 0; i < 32; i++)
+               if (u & ((uint32_t)1 << i))
+                       num++;
+       return num;
+}
+
+int bitops_weight64(uint64_t u)
+{
+       int i, num = 0;
+       for (i = 0; i < 64; i++)
+               if (u & ((uint64_t)1 << i))
+                       num++;
+       return num;
+}
+#endif