[ANNOUNCE] VDR-1.5.12: some "micro" speed improvements

Message ID 477417C7.2080707@gmx.de
State New

Commit Message

Reinhard Nissl Dec. 27, 2007, 9:23 p.m. UTC

the attached crc32 seems to be 2 % faster than the original.



--- ../vdr-1.5.12-orig/libsi/util.c	2006-02-18 12:17:50.000000000 +0100
+++ libsi/util.c	2007-12-27 22:14:56.000000000 +0100
@@ -219,58 +219,73 @@  time_t DVBTime::getDuration(unsigned cha
 //taken and adapted from libdtv, (c) Rolf Hakenes
 // CRC32 lookup table for polynomial 0x04c11db7
+// swapped bytes to avoid one shift operation in CRC loop (c) Reinhard Nissl
 u_int32_t CRC32::crc_table[256] = {
-   0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
-   0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
-   0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70, 0x48d0c6c7,
-   0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
-   0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3,
-   0x709f7b7a, 0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
-   0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
-   0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
-   0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb,
-   0xceb42022, 0xca753d95, 0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
-   0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
-   0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
-   0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4,
-   0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
-   0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08,
-   0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
-   0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
-   0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
-   0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, 0xe0b41de7, 0xe4750050,
-   0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
-   0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
-   0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
-   0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56, 0x4bc510e1,
-   0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
-   0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5,
-   0x3f9b762c, 0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
-   0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
-   0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
-   0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd,
-   0xcda1f604, 0xc960ebb3, 0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
-   0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
-   0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
-   0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2,
-   0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
-   0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e,
-   0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
-   0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
-   0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
-   0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, 0xe3a1cbc1, 0xe760d676,
-   0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
-   0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
-   0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
-   0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4};
+   0x00000000, 0xb71dc104, 0x6e3b8209, 0xd926430d, 0xdc760413, 0x6b6bc517,
+   0xb24d861a, 0x0550471e, 0xb8ed0826, 0x0ff0c922, 0xd6d68a2f, 0x61cb4b2b,
+   0x649b0c35, 0xd386cd31, 0x0aa08e3c, 0xbdbd4f38, 0x70db114c, 0xc7c6d048,
+   0x1ee09345, 0xa9fd5241, 0xacad155f, 0x1bb0d45b, 0xc2969756, 0x758b5652,
+   0xc836196a, 0x7f2bd86e, 0xa60d9b63, 0x11105a67, 0x14401d79, 0xa35ddc7d,
+   0x7a7b9f70, 0xcd665e74, 0xe0b62398, 0x57abe29c, 0x8e8da191, 0x39906095,
+   0x3cc0278b, 0x8bdde68f, 0x52fba582, 0xe5e66486, 0x585b2bbe, 0xef46eaba,
+   0x3660a9b7, 0x817d68b3, 0x842d2fad, 0x3330eea9, 0xea16ada4, 0x5d0b6ca0,
+   0x906d32d4, 0x2770f3d0, 0xfe56b0dd, 0x494b71d9, 0x4c1b36c7, 0xfb06f7c3,
+   0x2220b4ce, 0x953d75ca, 0x28803af2, 0x9f9dfbf6, 0x46bbb8fb, 0xf1a679ff,
+   0xf4f63ee1, 0x43ebffe5, 0x9acdbce8, 0x2dd07dec, 0x77708634, 0xc06d4730,
+   0x194b043d, 0xae56c539, 0xab068227, 0x1c1b4323, 0xc53d002e, 0x7220c12a,
+   0xcf9d8e12, 0x78804f16, 0xa1a60c1b, 0x16bbcd1f, 0x13eb8a01, 0xa4f64b05,
+   0x7dd00808, 0xcacdc90c, 0x07ab9778, 0xb0b6567c, 0x69901571, 0xde8dd475,
+   0xdbdd936b, 0x6cc0526f, 0xb5e61162, 0x02fbd066, 0xbf469f5e, 0x085b5e5a,
+   0xd17d1d57, 0x6660dc53, 0x63309b4d, 0xd42d5a49, 0x0d0b1944, 0xba16d840,
+   0x97c6a5ac, 0x20db64a8, 0xf9fd27a5, 0x4ee0e6a1, 0x4bb0a1bf, 0xfcad60bb,
+   0x258b23b6, 0x9296e2b2, 0x2f2bad8a, 0x98366c8e, 0x41102f83, 0xf60dee87,
+   0xf35da999, 0x4440689d, 0x9d662b90, 0x2a7bea94, 0xe71db4e0, 0x500075e4,
+   0x892636e9, 0x3e3bf7ed, 0x3b6bb0f3, 0x8c7671f7, 0x555032fa, 0xe24df3fe,
+   0x5ff0bcc6, 0xe8ed7dc2, 0x31cb3ecf, 0x86d6ffcb, 0x8386b8d5, 0x349b79d1,
+   0xedbd3adc, 0x5aa0fbd8, 0xeee00c69, 0x59fdcd6d, 0x80db8e60, 0x37c64f64,
+   0x3296087a, 0x858bc97e, 0x5cad8a73, 0xebb04b77, 0x560d044f, 0xe110c54b,
+   0x38368646, 0x8f2b4742, 0x8a7b005c, 0x3d66c158, 0xe4408255, 0x535d4351,
+   0x9e3b1d25, 0x2926dc21, 0xf0009f2c, 0x471d5e28, 0x424d1936, 0xf550d832,
+   0x2c769b3f, 0x9b6b5a3b, 0x26d61503, 0x91cbd407, 0x48ed970a, 0xfff0560e,
+   0xfaa01110, 0x4dbdd014, 0x949b9319, 0x2386521d, 0x0e562ff1, 0xb94beef5,
+   0x606dadf8, 0xd7706cfc, 0xd2202be2, 0x653deae6, 0xbc1ba9eb, 0x0b0668ef,
+   0xb6bb27d7, 0x01a6e6d3, 0xd880a5de, 0x6f9d64da, 0x6acd23c4, 0xddd0e2c0,
+   0x04f6a1cd, 0xb3eb60c9, 0x7e8d3ebd, 0xc990ffb9, 0x10b6bcb4, 0xa7ab7db0,
+   0xa2fb3aae, 0x15e6fbaa, 0xccc0b8a7, 0x7bdd79a3, 0xc660369b, 0x717df79f,
+   0xa85bb492, 0x1f467596, 0x1a163288, 0xad0bf38c, 0x742db081, 0xc3307185,
+   0x99908a5d, 0x2e8d4b59, 0xf7ab0854, 0x40b6c950, 0x45e68e4e, 0xf2fb4f4a,
+   0x2bdd0c47, 0x9cc0cd43, 0x217d827b, 0x9660437f, 0x4f460072, 0xf85bc176,
+   0xfd0b8668, 0x4a16476c, 0x93300461, 0x242dc565, 0xe94b9b11, 0x5e565a15,
+   0x87701918, 0x306dd81c, 0x353d9f02, 0x82205e06, 0x5b061d0b, 0xec1bdc0f,
+   0x51a69337, 0xe6bb5233, 0x3f9d113e, 0x8880d03a, 0x8dd09724, 0x3acd5620,
+   0xe3eb152d, 0x54f6d429, 0x7926a9c5, 0xce3b68c1, 0x171d2bcc, 0xa000eac8,
+   0xa550add6, 0x124d6cd2, 0xcb6b2fdf, 0x7c76eedb, 0xc1cba1e3, 0x76d660e7,
+   0xaff023ea, 0x18ede2ee, 0x1dbda5f0, 0xaaa064f4, 0x738627f9, 0xc49be6fd,
+   0x09fdb889, 0xbee0798d, 0x67c63a80, 0xd0dbfb84, 0xd58bbc9a, 0x62967d9e,
+   0xbbb03e93, 0x0cadff97, 0xb110b0af, 0x060d71ab, 0xdf2b32a6, 0x6836f3a2,
+   0x6d66b4bc, 0xda7b75b8, 0x035d36b5, 0xb440f7b1};
+inline void swap_bytes(u_int32_t &crc)
+  unsigned char a = crc >> 24;
+  unsigned char b = crc >> 16;
+  unsigned char c = crc >> 8;
+  unsigned char d = crc;
+  crc = ((d << 8 | c) << 8 | b) << 8 | a;
 u_int32_t CRC32::crc32 (const char *d, int len, u_int32_t crc)
    register int i;
    const unsigned char *u=(unsigned char*)d; // Saves '& 0xff'
+   swap_bytes(crc);
    for (i=0; i<len; i++)
-      crc = (crc << 8) ^ crc_table[((crc >> 24) ^ *u++)];
+      crc = (crc >> 8) ^ crc_table[(unsigned char)crc ^ *u++];
+   swap_bytes(crc);
    return crc;