}
#endif
}
+
+/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
+int
+ctz(uint32_t n)
+{
+ if (!n) {
+ return 32;
+ } else {
+#if !defined(UINT_MAX) || !defined(UINT32_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+ return __builtin_ctz(n);
+#else
+ unsigned int k;
+ int count = 31;
+
+#define CTZ_STEP(X) \
+ k = n << (X); \
+ if (k) { \
+ count -= X; \
+ n = k; \
+ }
+ CTZ_STEP(16);
+ CTZ_STEP(8);
+ CTZ_STEP(4);
+ CTZ_STEP(2);
+ CTZ_STEP(1);
+#undef CTZ_STEP
+
+ return count;
+#endif
+ }
+}
+
+/* Returns true if the 'n' bytes starting at 'p' are zeros. */
+bool
+is_all_zeros(const uint8_t *p, size_t n)
+{
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ if (p[i] != 0x00) {
+ return false;
+ }
+ }
+ return true;
+}
+
+/* Returns true if the 'n' bytes starting at 'p' are 0xff. */
+bool
+is_all_ones(const uint8_t *p, size_t n)
+{
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ if (p[i] != 0xff) {
+ return false;
+ }
+ }
+ return true;
+}
+