1 files changed, 115 insertions, 0 deletions
diff --git a/flatcc/external/hash/hash.h b/flatcc/external/hash/hash.h
new file mode 100644
index 0000000..c5a6fc6
--- /dev/null
+++ b/flatcc/external/hash/hash.h
@@ -0,0 +1,115 @@
+#ifndef HASH_H
+#define HASH_H
+
+/* Misc. hash functions that do not comply to a specific interface. */
+
+#include <stdlib.h>
+
+#ifdef _MSC_VER
+/* `inline` only advisory anyway. */
+#pragma warning(disable: 4710) /* function not inlined */
+#endif
+
+static inline uint32_t hash_fnv1a32_update(uint32_t seed, uint8_t *buf, size_t len)
+{
+    uint8_t *p = buf;
+#ifndef FNV1A_NOMUL
+    const uint64_t prime = UINT32_C(0x1000193);
+#endif
+    uint64_t hash = seed;
+
+    while (len--) {
+        hash ^= (uint64_t)*p++;
+#ifndef FNV1A_NOMUL
+        hash *= prime;
+#else
+        hash += (hash << 1) + (hash << 4) + (hash << 7) +
+            (hash << 8) + (hash << 24);
+#endif
+    }
+    return hash;
+}
+
+static inline uint32_t hash_fnv1a32(uint8_t *buf, size_t len)
+{
+    return hash_fnv1a32_update(UINT32_C(0x811c9dc5), buf, len);
+}
+
+static inline uint64_t hash_fnv1a64_update(uint64_t v, uint8_t *buf, size_t len)
+{
+    uint8_t *p = buf;
+#ifndef FNV1A_NOMUL
+    const uint64_t prime = UINT64_C(0x100000001b3);
+#endif
+    uint64_t hash = v;
+
+    while (len--) {
+        hash ^= (uint64_t)*p++;
+#ifndef FNV1A_NOMUL
+        hash *= prime;
+#else
+        hash += (hash << 1) + (hash << 4) + (hash << 5) +
+		    (hash << 7) + (hash << 8) + (hash << 40);
+#endif
+    }
+    return hash;
+}
+
+static inline uint64_t hash_fnv1a64(uint8_t *buf, size_t len)
+{
+    return hash_fnv1a64_update(UINT64_C(0xcbf29ce484222325), buf, len);
+}
+
+/*
+ * MurmurHash 3 final mix with seed to handle 0.
+ *
+ * Width is number of bits of the value to return.
+ * http://stackoverflow.com/a/12996028
+ */
+static inline uint32_t hash_bucket32(uint32_t v,  size_t width)
+{
+    uint32_t x = v + UINT32_C(0x2f693b52);
+
+    x = ((x >> 16) ^ x) * UINT32_C(0x45d9f3b);
+    x = ((x >> 16) ^ x) * UINT32_C(0x45d9f3b);
+    x = ((x >> 16) ^ x);
+    return x >> (32 - width);
+}
+
+/*
+ * SplitMix64 - can be used to disperse fnv1a hash, to hash
+ * an integer, or as a simple non-cryptographic prng.
+ *
+ * Width is number of bits of the value to return.
+ * http://stackoverflow.com/a/12996028
+ */
+static inline uint64_t hash_bucket64(uint64_t v, size_t width)
+{
+    uint64_t x = v + UINT64_C(0x9e3779b97f4a7c15);
+    
+    x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
+    x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb);
+    x = x ^ (x >> 31);
+    return x >> (64 - width);
+}
+
+static inline uint64_t hash_random64(uint64_t *state)
+{
+    uint64_t x;
+
+    x = hash_bucket64(*state, 64);
+    *state = x;
+    return x;
+}
+
+/*
+ * Faster, less random hash bucket compared to hash_bucket32, but works
+ * for smaller integers.
+ */
+static inline uint32_t hash_mult32(uint32_t v, size_t width)
+{
+    /* Knuth's multiplicative hash. */
+    return (v * UINT32_C(2654435761)) >> (32 - width);
+}
+
+#endif /* HASH_H */