mirror of https://git.tukaani.org/xz.git
175 lines
3.8 KiB
C
175 lines
3.8 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file crc64.c
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/// \brief CRC64 calculation
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//
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// Authors: Lasse Collin
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// Ilya Kurdyukov
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "check.h"
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#include "crc_common.h"
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#ifdef CRC_CLMUL
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# define BUILDING_CRC64_CLMUL
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# include "crc_x86_clmul.h"
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#endif
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#ifdef CRC_GENERIC
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/////////////////////////////////
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// Generic slice-by-four CRC64 //
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/////////////////////////////////
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#ifdef WORDS_BIGENDIAN
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# define A1(x) ((x) >> 56)
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#else
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# define A1 A
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#endif
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// See the comments in crc32_fast.c. They aren't duplicated here.
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static uint64_t
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crc64_generic(const uint8_t *buf, size_t size, uint64_t crc)
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{
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crc = ~crc;
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#ifdef WORDS_BIGENDIAN
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crc = bswap64(crc);
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#endif
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if (size > 4) {
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while ((uintptr_t)(buf) & 3) {
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crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
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--size;
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}
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const uint8_t *const limit = buf + (size & ~(size_t)(3));
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size &= (size_t)(3);
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while (buf < limit) {
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#ifdef WORDS_BIGENDIAN
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const uint32_t tmp = (uint32_t)(crc >> 32)
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^ aligned_read32ne(buf);
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#else
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const uint32_t tmp = (uint32_t)crc
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^ aligned_read32ne(buf);
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#endif
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buf += 4;
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crc = lzma_crc64_table[3][A(tmp)]
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^ lzma_crc64_table[2][B(tmp)]
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^ S32(crc)
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^ lzma_crc64_table[1][C(tmp)]
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^ lzma_crc64_table[0][D(tmp)];
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}
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}
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while (size-- != 0)
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crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
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#ifdef WORDS_BIGENDIAN
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crc = bswap64(crc);
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#endif
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return ~crc;
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}
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#endif
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#if defined(CRC_GENERIC) && defined(CRC_CLMUL)
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//////////////////////////
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// Function dispatching //
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//////////////////////////
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// If both the generic and CLMUL implementations are usable, then the
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// function that is used is selected at runtime. See crc32_fast.c.
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typedef uint64_t (*crc64_func_type)(
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const uint8_t *buf, size_t size, uint64_t crc);
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#if defined(HAVE_FUNC_ATTRIBUTE_IFUNC) && defined(__clang__)
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# pragma GCC diagnostic push
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# pragma GCC diagnostic ignored "-Wunused-function"
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#endif
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static crc64_func_type
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crc64_resolve(void)
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{
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return is_clmul_supported() ? &crc64_clmul : &crc64_generic;
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}
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#if defined(HAVE_FUNC_ATTRIBUTE_IFUNC) && defined(__clang__)
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# pragma GCC diagnostic pop
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#endif
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#ifndef HAVE_FUNC_ATTRIBUTE_IFUNC
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#ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
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# define CRC64_SET_FUNC_ATTR __attribute__((__constructor__))
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static crc64_func_type crc64_func;
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#else
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# define CRC64_SET_FUNC_ATTR
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static uint64_t crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc);
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static crc64_func_type crc64_func = &crc64_dispatch;
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#endif
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CRC64_SET_FUNC_ATTR
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static void
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crc64_set_func(void)
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{
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crc64_func = crc64_resolve();
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return;
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}
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#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR
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static uint64_t
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crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc)
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{
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crc64_set_func();
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return crc64_func(buf, size, crc);
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}
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#endif
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#endif
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#endif
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#ifdef CRC_USE_IFUNC
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extern LZMA_API(uint64_t)
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lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
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__attribute__((__ifunc__("crc64_resolve")));
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#else
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extern LZMA_API(uint64_t)
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lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
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{
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#if defined(CRC_GENERIC) && defined(CRC_CLMUL)
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#ifdef CRC_USE_GENERIC_FOR_SMALL_INPUTS
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if (size <= 16)
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return crc64_generic(buf, size, crc);
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#endif
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return crc64_func(buf, size, crc);
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#elif defined(CRC_CLMUL)
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// If CLMUL is used unconditionally without runtime CPU detection
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// then omitting the generic version and its 8 KiB lookup table
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// makes the library smaller.
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//
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// FIXME: Lookup table isn't currently omitted on 32-bit x86,
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// see crc64_table.c.
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return crc64_clmul(buf, size, crc);
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#else
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return crc64_generic(buf, size, crc);
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#endif
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}
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#endif
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