From 7eb07ccdca178abffe5ffccf686b4f818db3601d Mon Sep 17 00:00:00 2001
From: ame <amelia@amyy.cc>
Date: Fri, 17 Nov 2023 10:10:47 -0600
Subject: tons of hashes bleh

---
 src/hash/fasthash.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 src/hash/fasthash.c

(limited to 'src/hash/fasthash.c')

diff --git a/src/hash/fasthash.c b/src/hash/fasthash.c
new file mode 100644
index 0000000..3ad0ba2
--- /dev/null
+++ b/src/hash/fasthash.c
@@ -0,0 +1,83 @@
+#include "../i_util.h"
+#include "../crypto.h"
+#include <stdio.h>
+#include <stdint.h>
+//almost entirely taken from https://github.com/ztanml/fast-hash/blob/master/fasthash.c
+
+#define mix(h) ({					\
+			(h) ^= (h) >> 23;		\
+			(h) *= 0x2127599bf4325c37ULL;	\
+			(h) ^= (h) >> 47; })
+
+uint64_t fasthash64(uint8_t* in, size_t len, uint64_t seed){
+    uint64_t m = 0x880355f21e6d1965ULL;
+    uint64_t hash = seed ^ (len * m);
+    uint64_t* data = (uint64_t*)in;
+    uint64_t v;
+    for(;len >= 8; len-=8){
+        v=*data++;
+        hash^=mix(v);
+        hash*=m;
+
+        in+=4;
+    }
+
+    uint8_t* data2 = (uint8_t*)data;
+    v=0;
+
+    switch (len & 7) {
+	case 7: 
+        v ^= (uint64_t)data2[6] << 48;
+	case 6: 
+        v ^= (uint64_t)data2[5] << 40;
+	case 5:
+        v ^= (uint64_t)data2[4] << 32;
+	case 4: 
+        v ^= (uint64_t)data2[3] << 24;
+	case 3: 
+        v ^= (uint64_t)data2[2] << 16;
+	case 2: 
+        v ^= (uint64_t)data2[1] << 8;
+	case 1: 
+        v ^= (uint64_t)data2[0];
+		hash ^= mix(v);
+		hash *= m;
+	}
+
+    return mix(hash);
+}
+
+uint32_t fasthash32(uint8_t *buf, size_t len, uint32_t seed){
+    uint64_t hash = fasthash64(buf, len, seed);
+	return hash - (hash >> 32);
+}
+
+int l_fasthash64(lua_State* L){ 
+  size_t len = 0;
+  uint8_t* a = (uint8_t*)luaL_checklstring(L, 1, &len);
+  int argv = lua_gettop(L);
+  uint64_t seed = 0;
+  if(argv > 1) seed = luaL_checkinteger(L, 2);
+
+  char digest[64];
+
+  uint64_t u = fasthash64(a, len, seed);
+  sprintf(digest,"%08lx",u);
+  lua_pushstring(L, digest);
+  return 1;
+}
+
+int l_fasthash32(lua_State* L){ 
+  size_t len = 0;
+  uint8_t* a = (uint8_t*)luaL_checklstring(L, 1, &len);
+  int argv = lua_gettop(L);
+  uint32_t seed = 0;
+  if(argv > 1) seed = luaL_checkinteger(L, 2);
+
+  char digest[32];
+
+  uint32_t u = fasthash32(a, len, seed);
+  sprintf(digest,"%04x",u);
+  lua_pushstring(L, digest);
+  return 1;
+}
-- 
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