X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fcrc%2Fcrc.c;h=9fbb907d7ae2c44a4e2c41d7db064ede3ff679ff;hp=180d327cbdcd05b85ecc0753f73ab011823a5f69;hb=f5129b0c08976fbaa07d3d610de40677e81ad344;hpb=96b6d6f132aeec31adc0dfd0836f67e052694ac7 diff --git a/ccan/crc/crc.c b/ccan/crc/crc.c index 180d327c..9fbb907d 100644 --- a/ccan/crc/crc.c +++ b/ccan/crc/crc.c @@ -1,49 +1,116 @@ -/*- +/* crc32_ieee code: * COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or * code or tables extracted from it, as desired without restriction. - * - * First, the polynomial itself and its table of feedback terms. The - * polynomial is - * 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+X^0 - * - * Note that we take it "backwards" and put the highest-order term in - * the lowest-order bit. The X^32 term is "implied"; the LSB is the - * X^31 term, etc. The X^0 term (usually shown as "+1") results in - * the MSB being 1 - * - * Note that the usual hardware shift register implementation, which - * is what we're using (we're merely optimizing it by doing eight-bit - * chunks at a time) shifts bits into the lowest-order term. In our - * implementation, that means shifting towards the right. Why do we - * do it this way? Because the calculated CRC must be transmitted in - * order from highest-order term to lowest-order term. UARTs transmit - * characters in order from LSB to MSB. By storing the CRC this way - * we hand it to the UART in the order low-byte to high-byte; the UART - * sends each low-bit to hight-bit; and the result is transmission bit - * by bit from highest- to lowest-order term without requiring any bit - * shuffling on our part. Reception works similarly - * - * The feedback terms table consists of 256, 32-bit entries. Notes - * - * The table can be generated at runtime if desired; code to do so - * is shown later. It might not be obvious, but the feedback - * terms simply represent the results of eight shift/xor opera - * tions for all combinations of data and CRC register values - * - * The values must be right-shifted by eight bits by the "updcrc - * logic; the shift must be unsigned (bring in zeroes). On some - * hardware you could probably optimize the shift in assembler by - * using byte-swap instructions - * polynomial $edb88320 - * - * - * CRC32 code derived from work by Gary S. Brown. */ + +/* crc32c code taken from 2.6.29 Linux kernel crypto/crc32c.c: + * Copyright (c) 2004 Cisco Systems, Inc. + * Copyright (c) 2008 Herbert Xu + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. */ + #include "crc.h" #include #include -static const uint32_t crc32_tab[] = { +/* + * This is the CRC-32C table + * Generated with: + * width = 32 bits + * poly = 0x1EDC6F41 + * reflect input bytes = true + * reflect output bytes = true + */ +static const uint32_t crc32c_tab[] = { + 0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4, + 0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB, + 0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B, + 0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24, + 0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B, + 0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384, + 0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54, + 0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B, + 0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A, + 0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35, + 0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5, + 0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA, + 0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45, + 0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A, + 0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A, + 0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595, + 0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48, + 0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957, + 0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687, + 0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198, + 0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927, + 0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38, + 0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8, + 0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7, + 0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096, + 0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789, + 0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859, + 0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46, + 0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9, + 0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6, + 0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36, + 0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829, + 0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C, + 0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93, + 0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043, + 0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C, + 0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3, + 0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC, + 0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C, + 0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033, + 0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652, + 0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D, + 0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D, + 0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982, + 0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D, + 0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622, + 0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2, + 0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED, + 0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530, + 0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F, + 0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF, + 0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0, + 0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F, + 0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540, + 0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90, + 0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F, + 0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE, + 0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1, + 0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321, + 0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E, + 0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81, + 0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E, + 0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E, + 0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351 +}; + +/* + * Steps through buffer one byte at at time, calculates reflected + * crc using table. + */ +uint32_t crc32c(uint32_t crc, const void *buf, size_t size) +{ + const uint8_t *p = buf; + + while (size--) + crc = crc32c_tab[(crc ^ *p++) & 0xFFL] ^ (crc >> 8); + + return crc; +} + +const uint32_t *crc32c_table(void) +{ + return crc32c_tab; +} + +static const uint32_t crc32_ieee_tab[] = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, @@ -89,16 +156,20 @@ static const uint32_t crc32_tab[] = { 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d }; -uint32_t crc32(const void *buf, size_t size) +uint32_t crc32_ieee(uint32_t crc, const void *buf, size_t size) { const uint8_t *p; - uint32_t crc; p = buf; - crc = ~0U; + crc ^= ~0U; while (size--) - crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8); + crc = crc32_ieee_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8); return crc ^ ~0U; } + +const uint32_t *crc32_ieee_table(void) +{ + return crc32_ieee_tab; +}