+
+/* Returns an appropriate delimiter for inserting just before the 0-based item
+ * 'index' in a list that has 'total' items in it. */
+const char *
+english_list_delimiter(size_t index, size_t total)
+{
+ return (index == 0 ? ""
+ : index < total - 1 ? ", "
+ : total > 2 ? ", and "
+ : " and ");
+}
+
+/* Given a 32 bit word 'n', calculates floor(log_2('n')). This is equivalent
+ * to finding the bit position of the most significant one bit in 'n'. It is
+ * an error to call this function with 'n' == 0. */
+int
+log_2_floor(uint32_t n)
+{
+ assert(n);
+
+#if !defined(UINT_MAX) || !defined(UINT32_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+ return 31 - __builtin_clz(n);
+#else
+ {
+ int log = 0;
+
+#define BIN_SEARCH_STEP(BITS) \
+ if (n >= (1 << BITS)) { \
+ log += BITS; \
+ n >>= BITS; \
+ }
+ BIN_SEARCH_STEP(16);
+ BIN_SEARCH_STEP(8);
+ BIN_SEARCH_STEP(4);
+ BIN_SEARCH_STEP(2);
+ BIN_SEARCH_STEP(1);
+#undef BIN_SEARCH_STEP
+ return log;
+ }
+#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;
+}
+