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// Copyright 2010 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Implements multiword CRC for GCC on i386.
//
// Small comment: the trick described in
// http://software.intel.com/en-us/articles/fast-simd-integer-move-for-the-intel-pentiumr-4-processor
// (replace "movdqa dst, src" with "pshufd $0xE4, src, dst")
// did not work: execution time increased from
// 1.8 CPU cycles/byte to 2.1 CPU cycles/byte.
// So it may be good idea on P4 but it's not on newer CPUs.
//
// movaps/xorps vs. movdqa/pxor did not make any difference.
#include "generic_crc.h"
#include "uint128_sse2.h"
#if defined(__GNUC__) && CRCUTIL_USE_ASM && HAVE_AMD64 && HAVE_SSE2
namespace crcutil {
template<> uint128_sse2
GenericCrc<uint128_sse2, uint128_sse2, uint64, 4>::CrcMultiwordGccAmd64Sse2(
const uint8 *src, const uint8 *end, const uint128_sse2 &start) const;
template<>
uint128_sse2 GenericCrc<uint128_sse2, uint128_sse2, uint64, 4>::CrcMultiword(
const void *data, size_t bytes, const uint128_sse2 &start) const {
const uint8 *src = static_cast<const uint8 *>(data);
uint128_sse2 crc = start ^ this->Base().Canonize();
const uint8 *end = src + bytes;
if (bytes <= 7) {
for (; src < end; ++src) {
CRC_BYTE(this, crc, *src);
}
return (crc ^ this->Base().Canonize());
}
ALIGN_ON_WORD_BOUNDARY_IF_NEEDED(bytes, this, src, end, crc, uint64);
if (src >= end) {
return (crc ^ this->Base().Canonize());
}
return CrcMultiwordGccAmd64Sse2(src, end, crc);
}
#define CRC_WORD_ASM() \
SSE2_MOVQ " %[crc0], %[tmp0]\n" \
"xorq %[tmp0], %[buf0]\n" \
"psrldq $8, %[crc0]\n" \
"movzbq %b[buf0], %[tmp0]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp0], %[tmp0]\n" \
"pxor (%[table_word], %[tmp0], 8), %[crc0]\n" \
"movzbq %b[buf0], %[tmp1]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp1], %[tmp1]\n" \
"pxor 1*256*16(%[table_word], %[tmp1], 8), %[crc0]\n" \
"movzbq %b[buf0], %[tmp0]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp0], %[tmp0]\n" \
"pxor 2*256*16(%[table_word], %[tmp0], 8), %[crc0]\n" \
"movzbq %b[buf0], %[tmp1]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp1], %[tmp1]\n" \
"pxor 3*256*16(%[table_word], %[tmp1], 8), %[crc0]\n" \
"movzbq %b[buf0], %[tmp0]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp0], %[tmp0]\n" \
"pxor 4*256*16(%[table_word], %[tmp0], 8), %[crc0]\n" \
"movzbq %b[buf0], %[tmp1]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp1], %[tmp1]\n" \
"pxor 5*256*16(%[table_word], %[tmp1], 8), %[crc0]\n" \
"movzbq %b[buf0], %[tmp0]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp0], %[tmp0]\n" \
"pxor 6*256*16(%[table_word], %[tmp0], 8), %[crc0]\n" \
"addq %[buf0], %[buf0]\n" \
"pxor 7*256*16(%[table_word], %[buf0], 8), %[crc0]\n"
template<> uint128_sse2
GenericCrc<uint128_sse2, uint128_sse2, uint64, 4>::CrcMultiwordGccAmd64Sse2(
const uint8 *src, const uint8 *end, const uint128_sse2 &start) const {
__m128i crc0 = start;
__m128i crc1;
__m128i crc2;
__m128i crc3;
__m128i crc_carryover;
uint64 buf0;
uint64 buf1;
uint64 buf2;
uint64 buf3;
uint64 tmp0;
uint64 tmp1;
asm(
"sub $2*4*8 - 1, %[end]\n"
"cmpq %[src], %[end]\n"
"jbe 2f\n"
"pxor %[crc1], %[crc1]\n"
"pxor %[crc2], %[crc2]\n"
"pxor %[crc3], %[crc3]\n"
"pxor %[crc_carryover], %[crc_carryover]\n"
"movq (%[src]), %[buf0]\n"
"movq 1*8(%[src]), %[buf1]\n"
"movq 2*8(%[src]), %[buf2]\n"
"movq 3*8(%[src]), %[buf3]\n"
"1:\n"
#if HAVE_SSE && CRCUTIL_PREFETCH_WIDTH > 0
"prefetcht0 " TO_STRING(CRCUTIL_PREFETCH_WIDTH) "(%[src])\n"
#endif
#if GCC_VERSION_AVAILABLE(4, 5)
// Bug in GCC 4.2.4?
"add $4*8, %[src]\n"
#else
"lea 4*8(%[src]), %[src]\n"
#endif
"pxor %[crc_carryover], %[crc0]\n"
SSE2_MOVQ " %[crc0], %[tmp0]\n"
"psrldq $8, %[crc0]\n"
"xorq %[tmp0], %[buf0]\n"
"movzbq %b[buf0], %[tmp0]\n"
"pxor %[crc0], %[crc1]\n"
"addq %[tmp0], %[tmp0]\n"
"shrq $8, %[buf0]\n"
"movdqa (%[table], %[tmp0], 8), %[crc0]\n"
SSE2_MOVQ " %[crc1], %[tmp1]\n"
"psrldq $8, %[crc1]\n"
"xorq %[tmp1], %[buf1]\n"
"movzbq %b[buf1], %[tmp1]\n"
"pxor %[crc1], %[crc2]\n"
"addq %[tmp1], %[tmp1]\n"
"shrq $8, %[buf1]\n"
"movdqa (%[table], %[tmp1], 8), %[crc1]\n"
SSE2_MOVQ " %[crc2], %[tmp0]\n"
"psrldq $8, %[crc2]\n"
"xorq %[tmp0], %[buf2]\n"
"movzbq %b[buf2], %[tmp0]\n"
"pxor %[crc2], %[crc3]\n"
"addq %[tmp0], %[tmp0]\n"
"shrq $8, %[buf2]\n"
"movdqa (%[table], %[tmp0], 8), %[crc2]\n"
SSE2_MOVQ " %[crc3], %[tmp1]\n"
"psrldq $8, %[crc3]\n"
"xorq %[tmp1], %[buf3]\n"
"movzbq %b[buf3], %[tmp1]\n"
"movdqa %[crc3], %[crc_carryover]\n"
"addq %[tmp1], %[tmp1]\n"
"shrq $8, %[buf3]\n"
"movdqa (%[table], %[tmp1], 8), %[crc3]\n"
#define XOR(byte) \
"movzbq %b[buf0], %[tmp0]\n" \
"shrq $8, %[buf0]\n" \
"addq %[tmp0], %[tmp0]\n" \
"pxor " #byte "*256*16(%[table], %[tmp0], 8), %[crc0]\n" \
"movzbq %b[buf1], %[tmp1]\n" \
"shrq $8, %[buf1]\n" \
"addq %[tmp1], %[tmp1]\n" \
"pxor " #byte "*256*16(%[table], %[tmp1], 8), %[crc1]\n" \
"movzbq %b[buf2], %[tmp0]\n" \
"shrq $8, %[buf2]\n" \
"addq %[tmp0], %[tmp0]\n" \
"pxor " #byte "*256*16(%[table], %[tmp0], 8), %[crc2]\n" \
"movzbq %b[buf3], %[tmp1]\n" \
"shrq $8, %[buf3]\n" \
"addq %[tmp1], %[tmp1]\n" \
"pxor " #byte "*256*16(%[table], %[tmp1], 8), %[crc3]\n"
XOR(1)
XOR(2)
XOR(3)
XOR(4)
XOR(5)
XOR(6)
#undef XOR
"addq %[buf0], %[buf0]\n"
"pxor 7*256*16(%[table], %[buf0], 8), %[crc0]\n"
"movq (%[src]), %[buf0]\n"
"addq %[buf1], %[buf1]\n"
"pxor 7*256*16(%[table], %[buf1], 8), %[crc1]\n"
"movq 1*8(%[src]), %[buf1]\n"
"addq %[buf2], %[buf2]\n"
"pxor 7*256*16(%[table], %[buf2], 8), %[crc2]\n"
"movq 2*8(%[src]), %[buf2]\n"
"addq %[buf3], %[buf3]\n"
"pxor 7*256*16(%[table], %[buf3], 8), %[crc3]\n"
"movq 3*8(%[src]), %[buf3]\n"
"cmpq %[src], %[end]\n"
"ja 1b\n"
"pxor %[crc_carryover], %[crc0]\n"
CRC_WORD_ASM()
"pxor %[crc1], %[crc0]\n"
"movq %[buf1], %[buf0]\n"
CRC_WORD_ASM()
"pxor %[crc2], %[crc0]\n"
"movq %[buf2], %[buf0]\n"
CRC_WORD_ASM()
"pxor %[crc3], %[crc0]\n"
"movq %[buf3], %[buf0]\n"
CRC_WORD_ASM()
"add $4*8, %[src]\n"
"2:\n"
"add $2*4*8 - 8, %[end]\n"
"cmpq %[src], %[end]\n"
"jbe 4f\n"
"3:\n"
"movq (%[src]), %[buf0]\n"
"addq $8, %[src]\n"
CRC_WORD_ASM()
"cmpq %[src], %[end]\n"
"ja 3b\n"
"4:\n"
"add $7, %[end]\n"
"cmpq %[src], %[end]\n"
"jbe 6f\n"
"5:\n"
"movzbq (%[src]), %[buf0]\n"
"add $1, %[src]\n"
SSE2_MOVQ " %[crc0], %[tmp0]\n"
"movzx %b[tmp0], %[tmp0]\n"
"psrldq $1, %[crc0]\n"
"xor %[buf0], %[tmp0]\n"
"addq %[tmp0], %[tmp0]\n"
"pxor 7*256*16(%[table_word], %[tmp0], 8), %[crc0]\n"
"cmpq %[src], %[end]\n"
"ja 5b\n"
"6:\n"
: // outputs
[src] "+r" (src),
[end] "+r" (end),
[crc0] "+x" (crc0),
[crc1] "=&x" (crc1),
[crc2] "=&x" (crc2),
[crc3] "=&x" (crc3),
[crc_carryover] "=&x" (crc_carryover),
[buf0] "=&r" (buf0),
[buf1] "=&r" (buf1),
[buf2] "=&r" (buf2),
[buf3] "=&r" (buf3),
[tmp0] "=&r" (tmp0),
[tmp1] "=&r" (tmp1)
: // inputs
[table_word] "r" (this->crc_word_),
[table] "r" (this->crc_word_interleaved_));
return (this->Base().Canonize() ^ crc0);
}
} // namespace crcutil
#endif // defined(__GNUC__) && CRCUTIL_USE_ASM && HAVE_AMD64 && HAVE_SSE2
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