diff options
author | H. Peter Anvin <hpa@zytor.com> | 2009-12-22 10:24:14 -0800 |
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committer | H. Peter Anvin <hpa@zytor.com> | 2009-12-22 10:24:14 -0800 |
commit | a285577c484b98ff698f83f0dc5c0c8f7fbeb1f2 (patch) | |
tree | 1b02f35219361ccda1f50bd03b7669f7b5aff229 | |
parent | 1cd67f6eb8617be02f3a1af104100eb5869b6e20 (diff) | |
download | syslinux-a285577c484b98ff698f83f0dc5c0c8f7fbeb1f2.tar.gz |
btrfs: reduce size by computing the crc32c table on the fly
The crc32c algorithm requires a largish table (1K), however, it can be
computed at runtime using a fairly trivial piece of code. Even with
compression, this is substantially smaller.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r-- | core/fs/btrfs/btrfs.c | 2 | ||||
-rw-r--r-- | core/fs/btrfs/crc32c.h | 87 |
2 files changed, 20 insertions, 69 deletions
diff --git a/core/fs/btrfs/btrfs.c b/core/fs/btrfs/btrfs.c index 2092e29b..85aa56e8 100644 --- a/core/fs/btrfs/btrfs.c +++ b/core/fs/btrfs/btrfs.c @@ -621,6 +621,8 @@ static void btrfs_get_fs_tree(void) /* init. the fs meta data, return the block size shift bits. */ static int btrfs_fs_init(struct fs_info *_fs) { + btrfs_init_crc32c(); + fs = _fs; btrfs_read_super_block(); if (strncmp((char *)(&sb.magic), BTRFS_MAGIC, sizeof(sb.magic))) diff --git a/core/fs/btrfs/crc32c.h b/core/fs/btrfs/crc32c.h index 44960df2..2c317384 100644 --- a/core/fs/btrfs/crc32c.h +++ b/core/fs/btrfs/crc32c.h @@ -19,83 +19,32 @@ * reflect output bytes = true */ -static const u32 crc32c_table[256] = { - 0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L, - 0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL, - 0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL, - 0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L, - 0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL, - 0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L, - 0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L, - 0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL, - 0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL, - 0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L, - 0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L, - 0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL, - 0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L, - 0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL, - 0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL, - 0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L, - 0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L, - 0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L, - 0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L, - 0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L, - 0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L, - 0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L, - 0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L, - 0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L, - 0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L, - 0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L, - 0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L, - 0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L, - 0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L, - 0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L, - 0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L, - 0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L, - 0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL, - 0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L, - 0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L, - 0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL, - 0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L, - 0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL, - 0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL, - 0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L, - 0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L, - 0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL, - 0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL, - 0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L, - 0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL, - 0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L, - 0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L, - 0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL, - 0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L, - 0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL, - 0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL, - 0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L, - 0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL, - 0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L, - 0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L, - 0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL, - 0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL, - 0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L, - 0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L, - 0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL, - 0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L, - 0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL, - 0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL, - 0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L -}; +static u32 crc32c_table[256]; /* * Steps through buffer one byte at at time, calculates reflected * crc using table. */ -inline u32 crc32c_le(u32 crc, const char *data, size_t length) +static inline u32 crc32c_le(u32 crc, const char *data, size_t length) { while (length--) - crc = - crc32c_table[(crc ^ *data++) & 0xFFL] ^ (crc >> 8); + crc = crc32c_table[(u8)(crc ^ *data++)] ^ (crc >> 8); return crc; } + +static inline void btrfs_init_crc32c(void) +{ + int i, j; + u32 v; + const u32 poly = 0x82F63B78; /* Bit-reflected CRC32C polynomial */ + + for (i = 0; i < 256; i++) { + v = i; + for (j = 0; j < 8; j++) { + v = (v >> 1) ^ ((v & 1) ? poly : 0); + } + crc32c_table[i] = v; + } +} |