From: Chris Hanson <org/chris-hanson/cph>
Date: Sat, 26 Sep 2009 05:22:33 +0000 (-0700)
Subject: Fix definition of FNV hash.  Thanks Taylor!
X-Git-Tag: 20100708-Gtk~314
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=42f3c3ee32b83cae7933cb4b99b60ff03ff3ba79;p=mit-scheme.git

Fix definition of FNV hash.  Thanks Taylor!
---

diff --git a/src/microcode/intern.c b/src/microcode/intern.c
index fe8461766..9d44262d5 100644
--- a/src/microcode/intern.c
+++ b/src/microcode/intern.c
@@ -38,11 +38,12 @@ string_hash (uint32_t length, const char * string)
   const unsigned char * end = (scan + length);
   uint32_t result = 2166136261U;
   while (scan < end)
-    result = ((result * 16777619U) + (*scan++));
-#if (BIGGEST_FIXNUM >= 0xFFFFFFFF)
+    result = ((result * 16777619U) ^ ((uint32_t) (*scan++)));
+#if (FIXNUM_LENGTH >= 32)
   return (result);
 #else
-  return (result & ((uint32_t) BIGGEST_FIXNUM));
+  /* Shorten the result using xor-folding.  */
+  return ((result >> FIXNUM_LENGTH) ^ (result & FIXNUM_MASK));
 #endif
 }