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author | Linus Torvalds <torvalds@linux-foundation.org> | 2025-07-28 17:43:29 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2025-07-28 17:43:29 -0700 |
commit | a578dd095dfe8b56c167201d9aea43e47d27f807 (patch) | |
tree | 6d4ee6e286b92ebad6d10572af74eb15fd31973f /lib/crc/gen_crc32table.c | |
parent | 8e736a2eeaf261213b4557778e015699da1e1c8c (diff) | |
parent | 118da22eb6fbd48f896d17411f942399283d600c (diff) |
Merge tag 'crc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux
Pull CRC updates from Eric Biggers:
- Reorganize the architecture-optimized CRC code
It now lives in lib/crc/$(SRCARCH)/ rather than arch/$(SRCARCH)/lib/,
and it is no longer artificially split into separate generic and arch
modules. This allows better inlining and dead code elimination
The generic CRC code is also no longer exported, simplifying the API.
(This mirrors the similar changes to SHA-1 and SHA-2 in lib/crypto/,
which can be found in the "Crypto library updates" pull request)
- Improve crc32c() performance on newer x86_64 CPUs on long messages by
enabling the VPCLMULQDQ optimized code
- Simplify the crypto_shash wrappers for crc32_le() and crc32c()
Register just one shash algorithm for each that uses the (fully
optimized) library functions, instead of unnecessarily providing
direct access to the generic CRC code
- Remove unused and obsolete drivers for hardware CRC engines
- Remove CRC-32 combination functions that are no longer used
- Add kerneldoc for crc32_le(), crc32_be(), and crc32c()
- Convert the crc32() macro to an inline function
* tag 'crc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: (26 commits)
lib/crc: x86/crc32c: Enable VPCLMULQDQ optimization where beneficial
lib/crc: x86: Reorganize crc-pclmul static_call initialization
lib/crc: crc64: Add include/linux/crc64.h to kernel-api.rst
lib/crc: crc32: Change crc32() from macro to inline function and remove cast
nvmem: layouts: Switch from crc32() to crc32_le()
lib/crc: crc32: Document crc32_le(), crc32_be(), and crc32c()
lib/crc: Explicitly include <linux/export.h>
lib/crc: Remove ARCH_HAS_* kconfig symbols
lib/crc: x86: Migrate optimized CRC code into lib/crc/
lib/crc: sparc: Migrate optimized CRC code into lib/crc/
lib/crc: s390: Migrate optimized CRC code into lib/crc/
lib/crc: riscv: Migrate optimized CRC code into lib/crc/
lib/crc: powerpc: Migrate optimized CRC code into lib/crc/
lib/crc: mips: Migrate optimized CRC code into lib/crc/
lib/crc: loongarch: Migrate optimized CRC code into lib/crc/
lib/crc: arm64: Migrate optimized CRC code into lib/crc/
lib/crc: arm: Migrate optimized CRC code into lib/crc/
lib/crc: Prepare for arch-optimized code in subdirs of lib/crc/
lib/crc: Move files into lib/crc/
lib/crc32: Remove unused combination support
...
Diffstat (limited to 'lib/crc/gen_crc32table.c')
-rw-r--r-- | lib/crc/gen_crc32table.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/lib/crc/gen_crc32table.c b/lib/crc/gen_crc32table.c new file mode 100644 index 000000000000..9a7f31658e35 --- /dev/null +++ b/lib/crc/gen_crc32table.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <stdio.h> +#include "../../include/linux/crc32poly.h" +#include "../../include/generated/autoconf.h" +#include <inttypes.h> + +static uint32_t crc32table_le[256]; +static uint32_t crc32table_be[256]; +static uint32_t crc32ctable_le[256]; + +/** + * crc32init_le() - allocate and initialize LE table data + * + * crc is the crc of the byte i; other entries are filled in based on the + * fact that crctable[i^j] = crctable[i] ^ crctable[j]. + * + */ +static void crc32init_le_generic(const uint32_t polynomial, uint32_t tab[256]) +{ + unsigned i, j; + uint32_t crc = 1; + + tab[0] = 0; + + for (i = 128; i; i >>= 1) { + crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0); + for (j = 0; j < 256; j += 2 * i) + tab[i + j] = crc ^ tab[j]; + } +} + +static void crc32init_le(void) +{ + crc32init_le_generic(CRC32_POLY_LE, crc32table_le); +} + +static void crc32cinit_le(void) +{ + crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le); +} + +/** + * crc32init_be() - allocate and initialize BE table data + */ +static void crc32init_be(void) +{ + unsigned i, j; + uint32_t crc = 0x80000000; + + crc32table_be[0] = 0; + + for (i = 1; i < 256; i <<= 1) { + crc = (crc << 1) ^ ((crc & 0x80000000) ? CRC32_POLY_BE : 0); + for (j = 0; j < i; j++) + crc32table_be[i + j] = crc ^ crc32table_be[j]; + } +} + +static void output_table(const uint32_t table[256]) +{ + int i; + + for (i = 0; i < 256; i += 4) { + printf("\t0x%08x, 0x%08x, 0x%08x, 0x%08x,\n", + table[i], table[i + 1], table[i + 2], table[i + 3]); + } +} + +int main(int argc, char** argv) +{ + printf("/* this file is generated - do not edit */\n\n"); + + crc32init_le(); + printf("static const u32 ____cacheline_aligned crc32table_le[256] = {\n"); + output_table(crc32table_le); + printf("};\n"); + + crc32init_be(); + printf("static const u32 ____cacheline_aligned crc32table_be[256] = {\n"); + output_table(crc32table_be); + printf("};\n"); + + crc32cinit_le(); + printf("static const u32 ____cacheline_aligned crc32ctable_le[256] = {\n"); + output_table(crc32ctable_le); + printf("};\n"); + + return 0; +} |