Use the crc64 we already use as the perfect hash function prehash

Use the same crc64 that we already use for the symbol table hash as
the perfect hash function prehash.  We appear to get radically faster
convergence this way, and the crc64 is probably *faster*, since the
table likely to be resident in memory.

1 files changed, 8 insertions, 14 deletions

diff --git a/pptok.pl b/pptok.pl
index a835bf3..f918e35 100755
--- a/pptok.pl
+++ b/pptok.pl
@@ -141,12 +141,10 @@ if ($what eq 'c') {
     print OUT "#include <inttypes.h>\n";
     print OUT "#include <ctype.h>\n";
     print OUT "#include \"nasmlib.h\"\n";
+    print OUT "#include \"hashtbl.h\"\n";
     print OUT "#include \"preproc.h\"\n";
     print OUT "\n";
 
-    print OUT "#define rot(x,y) (((uint32_t)(x) << (y))+((uint32_t)(x) >> (32-(y))))\n";
-    print OUT "\n";
-
     # Note that this is global.
     printf OUT "const char * const pp_directives[%d] = {\n", scalar(@pptok);
     foreach $d (@pptok) {
@@ -180,22 +178,18 @@ if ($what eq 'c') {
     }
     print OUT "    };\n";
     
-    print OUT  "    uint32_t k1 = 0, k2 = 0;\n";
-    print OUT  "    uint8_t c;\n";
+    print OUT  "    uint32_t k1, k2;\n";
+    print OUT  "    uint64_t crc;\n";
     # For correct overflow behavior, "ix" should be unsigned of the same
     # width as the hash arrays.
     print OUT  "    uint16_t ix;\n";
-    print OUT  "    const char *p = token;\n";
     print OUT  "\n";
 
-    print OUT  "    while ((c = *p++) != 0) {\n";
-    print OUT  "        uint32_t kn1, kn2;\n";
-    print OUT  "        c |= 0x20; /* convert to lower case */\n";
-    printf OUT "        kn1 = rot(k1,%2d)^(rot(k2,%2d) + c);\n", ${$sv}[0], ${$sv}[1];
-    printf OUT "        kn2 = rot(k2,%2d)^(rot(k1,%2d) + c);\n", ${$sv}[2], ${$sv}[3];
-    print OUT  "        k1 = kn1; k2 = kn2;\n";
-    print OUT  "    }\n";
-    print OUT  "\n";
+    printf OUT "    crc = crc64i(UINT64_C(0x%08x%08x), token);\n",
+    	$$sv[0], $$sv[1];
+    print  OUT "    k1 = (uint32_t)crc;\n";
+    print  OUT "    k2 = (uint32_t)(crc >> 32);\n";
+    print  OUT "\n";
     printf OUT "    ix = hash1[k1 & 0x%x] + hash2[k2 & 0x%x];\n", $n-1, $n-1;
     printf OUT "    if (ix >= %d)\n", scalar(@pptok);
     print OUT  "        return PP_INVALID;\n";