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c6f371bab2
XZ_EXTERN was used to make internal functions static in the preboot code. However, in other decompressors this hasn't been done. On x86-64, this makes no difference to the kernel image size. Omit XZ_EXTERN and let some of the internal functions be extern in the preboot code. Omitting XZ_EXTERN from include/linux/xz.h fixes warnings in "make htmldocs" and makes the intradocument links to xz_dec functions work in Documentation/staging/xz.rst. The alternative would have been to add "XZ_EXTERN" to c_id_attributes in Documentation/conf.py but omitting XZ_EXTERN seemed cleaner. Link: https://lore.kernel.org/lkml/20240723205437.3c0664b0@kaneli/ Link: https://lkml.kernel.org/r/20240724110544.16430-1-lasse.collin@tukaani.org Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Jonathan Corbet <corbet@lwn.net> Cc: Sam James <sam@gentoo.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Joel Stanley <joel@jms.id.au> Cc: Jubin Zhong <zhongjubin@huawei.com> Cc: Jules Maselbas <jmaselbas@zdiv.net> Cc: Krzysztof Kozlowski <krzk@kernel.org> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rui Li <me@lirui.org> Cc: Simon Glass <sjg@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
59 lines
1.1 KiB
C
59 lines
1.1 KiB
C
// SPDX-License-Identifier: 0BSD
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/*
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* CRC32 using the polynomial from IEEE-802.3
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*
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* Authors: Lasse Collin <lasse.collin@tukaani.org>
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* Igor Pavlov <https://7-zip.org/>
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*/
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/*
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* This is not the fastest implementation, but it is pretty compact.
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* The fastest versions of xz_crc32() on modern CPUs without hardware
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* accelerated CRC instruction are 3-5 times as fast as this version,
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* but they are bigger and use more memory for the lookup table.
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*/
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#include "xz_private.h"
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/*
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* STATIC_RW_DATA is used in the pre-boot environment on some architectures.
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* See <linux/decompress/mm.h> for details.
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*/
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#ifndef STATIC_RW_DATA
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# define STATIC_RW_DATA static
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#endif
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STATIC_RW_DATA uint32_t xz_crc32_table[256];
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void xz_crc32_init(void)
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{
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const uint32_t poly = 0xEDB88320;
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uint32_t i;
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uint32_t j;
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uint32_t r;
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for (i = 0; i < 256; ++i) {
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r = i;
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for (j = 0; j < 8; ++j)
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r = (r >> 1) ^ (poly & ~((r & 1) - 1));
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xz_crc32_table[i] = r;
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}
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return;
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}
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uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
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{
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crc = ~crc;
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while (size != 0) {
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crc = xz_crc32_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
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--size;
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}
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return ~crc;
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}
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