use zlib crc32() rather our own implementation

They compute the same thing, only zlib can do it four bytes at once.
Since crc32() is used when loading documents, with larger documents
this is a difference than can be measured (not much, but a couple
percent of loading time). And we already depend on zlib anyway.

Change-Id: I65c5a1f050af717a5a2d6e334e216d42c4e4dbbb
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/110651
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

2 files changed, 13 insertions, 116 deletions

diff --git a/sal/Library_sal.mk b/sal/Library_sal.mk
index fbc02f26d6da..d783c84e39e9 100644
--- a/sal/Library_sal.mk
+++ b/sal/Library_sal.mk
@@ -41,6 +41,7 @@ $(eval $(call gb_Library_use_libraries,sal,\
 $(eval $(call gb_Library_use_externals,sal,\
     dtoa \
     valgrind \
+    zlib \
 ))
 
 $(eval $(call gb_Library_use_system_win32_libs,sal,\
diff --git a/sal/rtl/crc.cxx b/sal/rtl/crc.cxx
index 621b01643b4c..7912b15d066c 100644
--- a/sal/rtl/crc.cxx
+++ b/sal/rtl/crc.cxx
@@ -19,130 +19,26 @@
 
 #include <sal/types.h>
 #include <rtl/crc.h>
+#include <cassert>
 
-/**
-    rtl_crc32Table (CRC polynomial 0xEDB88320).
-*/
-const sal_uInt32 rtl_crc32Table[256] =
-{
-    /* 0 */
-    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
-    0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
-    0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
-    0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
-
-    /* 1 */
-    0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
-    0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
-    0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
-    0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
-
-    /* 2 */
-    0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
-    0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
-    0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,
-    0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
-
-    /* 3 */
-    0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
-    0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
-    0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
-    0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
-
-    /* 4 */
-    0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,
-    0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
-    0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,
-    0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
-
-    /* 5 */
-    0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
-    0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
-    0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
-    0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
-
-    /* 6 */
-    0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
-    0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
-    0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
-    0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
-
-    /* 7 */
-    0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,
-    0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
-    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,
-    0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
-
-    /* 8 */
-    0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
-    0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
-    0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
-    0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
-
-    /* 9 */
-    0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,
-    0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
-    0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
-    0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
+#include <zlib.h>
 
-    /* A */
-    0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,
-    0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
-    0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,
-    0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
-
-    /* B */
-    0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
-    0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
-    0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,
-    0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
-
-    /* C */
-    0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,
-    0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
-    0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
-    0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
-
-    /* D */
-    0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,
-    0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
-    0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
-    0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
-
-    /* E */
-    0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
-    0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
-    0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,
-    0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
-
-    /* F */
-    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,
-    0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
-    0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
-    0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
-};
-
-#define UPDCRC32(crc, octet) \
-    (rtl_crc32Table[((crc) ^ (octet)) & 0xff] ^ ((crc) >> 8))
+// Zlib's crc32() is very fast, so simply use that one instead
+// of implementing this ourselves.
 
 sal_uInt32 SAL_CALL rtl_crc32 (
     sal_uInt32  Crc,
     const void *Data, sal_uInt32 DatLen) SAL_THROW_EXTERN_C()
 {
+    // Check that our types map to zlib correctly.
+    static_assert(sizeof(uLong) >= sizeof(sal_uInt32));
+    static_assert(sizeof(uInt) >= sizeof(sal_uInt32));
+    // Our API says that Crc should be initialized to 0, while
+    // zlib says it should be initialized with 'crc32(0,Z_NULL,0)',
+    // which however simply returns 0. Ensure this.
+    assert(crc32(0, Z_NULL, 0) == 0);
     if (Data)
-    {
-        const sal_uInt8 *p = static_cast<const sal_uInt8 *>(Data);
-        const sal_uInt8 *q = p + DatLen;
-
-        Crc = ~Crc;
-
-        while (p < q)
-        {
-            Crc = UPDCRC32(Crc, *(p++));
-        }
-
-        Crc = ~Crc;
-    }
+        Crc = crc32( Crc, static_cast<const Bytef*>(Data), DatLen);
     return Crc;
 }