Message style improvements

[postgresql] / src / backend / utils / hash / pg_crc.c

diff --git a/src/backend/utils/hash/pg_crc.c b/src/backend/utils/hash/pg_crc.c
index bf23242a5ad74d5b239fc866f33234c5dd7890cb..51054108767971f16217d8fa543a478f7fe6f70d 100644 (file)
--- a/src/backend/utils/hash/pg_crc.c
+++ b/src/backend/utils/hash/pg_crc.c
@@ -1,25 +1,122 @@
 /*-------------------------------------------------------------------------
  *
  * pg_crc.c
- *       PostgreSQL 64-bit CRC support
+ *       PostgreSQL CRC support
  *
- * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
+ * See Ross Williams' excellent introduction
+ * A PAINLESS GUIDE TO CRC ERROR DETECTION ALGORITHMS, available from
+ * ftp://ftp.rocksoft.com/papers/crc_v3.txt or several other net sites.
+ *
+ * We use a normal (not "reflected", in Williams' terms) CRC, using initial
+ * all-ones register contents and a final bit inversion.
+ *
+ * The 64-bit variant is not used as of PostgreSQL 8.1, but we retain the
+ * code for possible future use.
+ *
+ *
+ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/hash/pg_crc.c,v 1.12 2004/12/31 22:01:37 pgsql Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/hash/pg_crc.c,v 1.16 2006/07/14 14:52:25 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
-#include "utils/pg_crc.h"
 
 
+/*
+ * This table is based on the polynomial
+ *     x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.
+ * (This is the same polynomial used in Ethernet checksums, for instance.)
+ */
+const uint32 pg_crc32_table[256] = {
+       0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
+       0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
+       0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
+       0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
+       0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
+       0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
+       0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
+       0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
+       0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
+       0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
+       0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,
+       0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
+       0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
+       0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
+       0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
+       0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
+       0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,
+       0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
+       0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,
+       0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
+       0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
+       0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
+       0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
+       0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
+       0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
+       0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
+       0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
+       0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
+       0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,
+       0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
+       0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,
+       0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
+       0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
+       0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
+       0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
+       0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
+       0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,
+       0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
+       0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
+       0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
+       0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,
+       0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
+       0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,
+       0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
+       0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
+       0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
+       0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,
+       0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
+       0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,
+       0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
+       0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
+       0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
+       0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,
+       0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
+       0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
+       0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
+       0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
+       0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
+       0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,
+       0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
+       0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,
+       0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
+       0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
+       0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
+};
+
+
+#ifdef PROVIDE_64BIT_CRC
+
+/*
+ * This table is based on the polynomial
+ *
+ * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
+ * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
+ * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
+ * x^7 + x^4 + x + 1
+ *
+ * which is borrowed from the DLT1 spec
+ * (ECMA-182, available from http://www.ecma.ch/ecma1/STAND/ECMA-182.HTM)
+ */
+
 #ifdef INT64_IS_BUSTED
 
-const uint32 crc_table0[256] = {
+const uint32 pg_crc64_table0[256] = {
        0x00000000, 0xA9EA3693,
        0x53D46D26, 0xFA3E5BB5,
        0x0E42ECDF, 0xA7A8DA4C,
@@ -150,7 +247,7 @@ const uint32 crc_table0[256] = {
        0x676F8394, 0xCE85B507
 };
 
-const uint32 crc_table1[256] = {
+const uint32 pg_crc64_table1[256] = {
        0x00000000, 0x42F0E1EB,
        0x85E1C3D7, 0xC711223C,
        0x49336645, 0x0BC387AE,
@@ -280,10 +377,9 @@ const uint32 crc_table1[256] = {
        0x5DEDC41A, 0x1F1D25F1,
        0xD80C07CD, 0x9AFCE626
 };
-
 #else                                                  /* int64 works */
 
-const uint64 crc_table[256] = {
+const uint64 pg_crc64_table[256] = {
        UINT64CONST(0x0000000000000000), UINT64CONST(0x42F0E1EBA9EA3693),
        UINT64CONST(0x85E1C3D753D46D26), UINT64CONST(0xC711223CFA3E5BB5),
        UINT64CONST(0x493366450E42ECDF), UINT64CONST(0x0BC387AEA7A8DA4C),
@@ -413,5 +509,6 @@ const uint64 crc_table[256] = {
        UINT64CONST(0x5DEDC41A34BBEEB2), UINT64CONST(0x1F1D25F19D51D821),
        UINT64CONST(0xD80C07CD676F8394), UINT64CONST(0x9AFCE626CE85B507)
 };
-
 #endif   /* INT64_IS_BUSTED */
+
+#endif   /* PROVIDE_64BIT_CRC */