334 lines
11 KiB
ArmAsm
334 lines
11 KiB
ArmAsm
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########################################################################
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# Implement fast CRC-T10DIF computation with SSE and PCLMULQDQ instructions
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#
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# Copyright (c) 2013, Intel Corporation
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#
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# Authors:
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# Erdinc Ozturk <erdinc.ozturk@intel.com>
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# Vinodh Gopal <vinodh.gopal@intel.com>
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# James Guilford <james.guilford@intel.com>
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# Tim Chen <tim.c.chen@linux.intel.com>
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#
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# This software is available to you under a choice of one of two
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# licenses. You may choose to be licensed under the terms of the GNU
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# General Public License (GPL) Version 2, available from the file
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# COPYING in the main directory of this source tree, or the
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# OpenIB.org BSD license below:
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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#
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# * Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the
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# distribution.
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#
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# * Neither the name of the Intel Corporation nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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#
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# THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION ""AS IS"" AND ANY
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# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL CORPORATION OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# Reference paper titled "Fast CRC Computation for Generic
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# Polynomials Using PCLMULQDQ Instruction"
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# URL: http://www.intel.com/content/dam/www/public/us/en/documents
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# /white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
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#
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#include <linux/linkage.h>
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.text
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#define init_crc %edi
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#define buf %rsi
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#define len %rdx
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#define FOLD_CONSTS %xmm10
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#define BSWAP_MASK %xmm11
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# Fold reg1, reg2 into the next 32 data bytes, storing the result back into
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# reg1, reg2.
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.macro fold_32_bytes offset, reg1, reg2
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movdqu \offset(buf), %xmm9
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movdqu \offset+16(buf), %xmm12
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pshufb BSWAP_MASK, %xmm9
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pshufb BSWAP_MASK, %xmm12
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movdqa \reg1, %xmm8
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movdqa \reg2, %xmm13
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pclmulqdq $0x00, FOLD_CONSTS, \reg1
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pclmulqdq $0x11, FOLD_CONSTS, %xmm8
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pclmulqdq $0x00, FOLD_CONSTS, \reg2
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pclmulqdq $0x11, FOLD_CONSTS, %xmm13
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pxor %xmm9 , \reg1
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xorps %xmm8 , \reg1
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pxor %xmm12, \reg2
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xorps %xmm13, \reg2
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.endm
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# Fold src_reg into dst_reg.
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.macro fold_16_bytes src_reg, dst_reg
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movdqa \src_reg, %xmm8
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pclmulqdq $0x11, FOLD_CONSTS, \src_reg
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pclmulqdq $0x00, FOLD_CONSTS, %xmm8
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pxor %xmm8, \dst_reg
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xorps \src_reg, \dst_reg
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.endm
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#
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# u16 crc_t10dif_pcl(u16 init_crc, const *u8 buf, size_t len);
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#
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# Assumes len >= 16.
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#
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.align 16
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ENTRY(crc_t10dif_pcl)
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movdqa .Lbswap_mask(%rip), BSWAP_MASK
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# For sizes less than 256 bytes, we can't fold 128 bytes at a time.
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cmp $256, len
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jl .Lless_than_256_bytes
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# Load the first 128 data bytes. Byte swapping is necessary to make the
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# bit order match the polynomial coefficient order.
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movdqu 16*0(buf), %xmm0
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movdqu 16*1(buf), %xmm1
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movdqu 16*2(buf), %xmm2
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movdqu 16*3(buf), %xmm3
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movdqu 16*4(buf), %xmm4
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movdqu 16*5(buf), %xmm5
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movdqu 16*6(buf), %xmm6
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movdqu 16*7(buf), %xmm7
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add $128, buf
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pshufb BSWAP_MASK, %xmm0
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pshufb BSWAP_MASK, %xmm1
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pshufb BSWAP_MASK, %xmm2
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pshufb BSWAP_MASK, %xmm3
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pshufb BSWAP_MASK, %xmm4
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pshufb BSWAP_MASK, %xmm5
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pshufb BSWAP_MASK, %xmm6
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pshufb BSWAP_MASK, %xmm7
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# XOR the first 16 data *bits* with the initial CRC value.
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pxor %xmm8, %xmm8
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pinsrw $7, init_crc, %xmm8
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pxor %xmm8, %xmm0
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movdqa .Lfold_across_128_bytes_consts(%rip), FOLD_CONSTS
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# Subtract 128 for the 128 data bytes just consumed. Subtract another
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# 128 to simplify the termination condition of the following loop.
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sub $256, len
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# While >= 128 data bytes remain (not counting xmm0-7), fold the 128
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# bytes xmm0-7 into them, storing the result back into xmm0-7.
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.Lfold_128_bytes_loop:
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fold_32_bytes 0, %xmm0, %xmm1
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fold_32_bytes 32, %xmm2, %xmm3
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fold_32_bytes 64, %xmm4, %xmm5
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fold_32_bytes 96, %xmm6, %xmm7
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add $128, buf
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sub $128, len
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jge .Lfold_128_bytes_loop
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# Now fold the 112 bytes in xmm0-xmm6 into the 16 bytes in xmm7.
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# Fold across 64 bytes.
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movdqa .Lfold_across_64_bytes_consts(%rip), FOLD_CONSTS
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fold_16_bytes %xmm0, %xmm4
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fold_16_bytes %xmm1, %xmm5
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fold_16_bytes %xmm2, %xmm6
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fold_16_bytes %xmm3, %xmm7
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# Fold across 32 bytes.
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movdqa .Lfold_across_32_bytes_consts(%rip), FOLD_CONSTS
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fold_16_bytes %xmm4, %xmm6
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fold_16_bytes %xmm5, %xmm7
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# Fold across 16 bytes.
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movdqa .Lfold_across_16_bytes_consts(%rip), FOLD_CONSTS
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fold_16_bytes %xmm6, %xmm7
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# Add 128 to get the correct number of data bytes remaining in 0...127
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# (not counting xmm7), following the previous extra subtraction by 128.
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# Then subtract 16 to simplify the termination condition of the
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# following loop.
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add $128-16, len
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# While >= 16 data bytes remain (not counting xmm7), fold the 16 bytes
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# xmm7 into them, storing the result back into xmm7.
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jl .Lfold_16_bytes_loop_done
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.Lfold_16_bytes_loop:
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movdqa %xmm7, %xmm8
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pclmulqdq $0x11, FOLD_CONSTS, %xmm7
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pclmulqdq $0x00, FOLD_CONSTS, %xmm8
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pxor %xmm8, %xmm7
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movdqu (buf), %xmm0
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pshufb BSWAP_MASK, %xmm0
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pxor %xmm0 , %xmm7
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add $16, buf
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sub $16, len
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jge .Lfold_16_bytes_loop
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.Lfold_16_bytes_loop_done:
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# Add 16 to get the correct number of data bytes remaining in 0...15
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# (not counting xmm7), following the previous extra subtraction by 16.
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add $16, len
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je .Lreduce_final_16_bytes
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.Lhandle_partial_segment:
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# Reduce the last '16 + len' bytes where 1 <= len <= 15 and the first 16
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# bytes are in xmm7 and the rest are the remaining data in 'buf'. To do
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# this without needing a fold constant for each possible 'len', redivide
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# the bytes into a first chunk of 'len' bytes and a second chunk of 16
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# bytes, then fold the first chunk into the second.
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movdqa %xmm7, %xmm2
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# xmm1 = last 16 original data bytes
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movdqu -16(buf, len), %xmm1
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pshufb BSWAP_MASK, %xmm1
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# xmm2 = high order part of second chunk: xmm7 left-shifted by 'len' bytes.
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lea .Lbyteshift_table+16(%rip), %rax
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sub len, %rax
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movdqu (%rax), %xmm0
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pshufb %xmm0, %xmm2
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# xmm7 = first chunk: xmm7 right-shifted by '16-len' bytes.
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pxor .Lmask1(%rip), %xmm0
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pshufb %xmm0, %xmm7
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# xmm1 = second chunk: 'len' bytes from xmm1 (low-order bytes),
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# then '16-len' bytes from xmm2 (high-order bytes).
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pblendvb %xmm2, %xmm1 #xmm0 is implicit
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# Fold the first chunk into the second chunk, storing the result in xmm7.
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movdqa %xmm7, %xmm8
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pclmulqdq $0x11, FOLD_CONSTS, %xmm7
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pclmulqdq $0x00, FOLD_CONSTS, %xmm8
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pxor %xmm8, %xmm7
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pxor %xmm1, %xmm7
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.Lreduce_final_16_bytes:
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# Reduce the 128-bit value M(x), stored in xmm7, to the final 16-bit CRC
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# Load 'x^48 * (x^48 mod G(x))' and 'x^48 * (x^80 mod G(x))'.
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movdqa .Lfinal_fold_consts(%rip), FOLD_CONSTS
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# Fold the high 64 bits into the low 64 bits, while also multiplying by
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# x^64. This produces a 128-bit value congruent to x^64 * M(x) and
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# whose low 48 bits are 0.
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movdqa %xmm7, %xmm0
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pclmulqdq $0x11, FOLD_CONSTS, %xmm7 # high bits * x^48 * (x^80 mod G(x))
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pslldq $8, %xmm0
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pxor %xmm0, %xmm7 # + low bits * x^64
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# Fold the high 32 bits into the low 96 bits. This produces a 96-bit
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# value congruent to x^64 * M(x) and whose low 48 bits are 0.
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movdqa %xmm7, %xmm0
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pand .Lmask2(%rip), %xmm0 # zero high 32 bits
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psrldq $12, %xmm7 # extract high 32 bits
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pclmulqdq $0x00, FOLD_CONSTS, %xmm7 # high 32 bits * x^48 * (x^48 mod G(x))
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pxor %xmm0, %xmm7 # + low bits
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# Load G(x) and floor(x^48 / G(x)).
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movdqa .Lbarrett_reduction_consts(%rip), FOLD_CONSTS
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# Use Barrett reduction to compute the final CRC value.
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movdqa %xmm7, %xmm0
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pclmulqdq $0x11, FOLD_CONSTS, %xmm7 # high 32 bits * floor(x^48 / G(x))
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psrlq $32, %xmm7 # /= x^32
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pclmulqdq $0x00, FOLD_CONSTS, %xmm7 # *= G(x)
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psrlq $48, %xmm0
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pxor %xmm7, %xmm0 # + low 16 nonzero bits
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# Final CRC value (x^16 * M(x)) mod G(x) is in low 16 bits of xmm0.
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pextrw $0, %xmm0, %eax
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ret
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.align 16
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.Lless_than_256_bytes:
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# Checksumming a buffer of length 16...255 bytes
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# Load the first 16 data bytes.
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movdqu (buf), %xmm7
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pshufb BSWAP_MASK, %xmm7
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add $16, buf
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# XOR the first 16 data *bits* with the initial CRC value.
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pxor %xmm0, %xmm0
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pinsrw $7, init_crc, %xmm0
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pxor %xmm0, %xmm7
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movdqa .Lfold_across_16_bytes_consts(%rip), FOLD_CONSTS
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cmp $16, len
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je .Lreduce_final_16_bytes # len == 16
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sub $32, len
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jge .Lfold_16_bytes_loop # 32 <= len <= 255
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add $16, len
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jmp .Lhandle_partial_segment # 17 <= len <= 31
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ENDPROC(crc_t10dif_pcl)
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.section .rodata, "a", @progbits
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.align 16
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# Fold constants precomputed from the polynomial 0x18bb7
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# G(x) = x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + x^0
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.Lfold_across_128_bytes_consts:
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.quad 0x0000000000006123 # x^(8*128) mod G(x)
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.quad 0x0000000000002295 # x^(8*128+64) mod G(x)
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.Lfold_across_64_bytes_consts:
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.quad 0x0000000000001069 # x^(4*128) mod G(x)
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.quad 0x000000000000dd31 # x^(4*128+64) mod G(x)
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.Lfold_across_32_bytes_consts:
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.quad 0x000000000000857d # x^(2*128) mod G(x)
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.quad 0x0000000000007acc # x^(2*128+64) mod G(x)
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.Lfold_across_16_bytes_consts:
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.quad 0x000000000000a010 # x^(1*128) mod G(x)
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.quad 0x0000000000001faa # x^(1*128+64) mod G(x)
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.Lfinal_fold_consts:
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.quad 0x1368000000000000 # x^48 * (x^48 mod G(x))
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.quad 0x2d56000000000000 # x^48 * (x^80 mod G(x))
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.Lbarrett_reduction_consts:
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.quad 0x0000000000018bb7 # G(x)
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.quad 0x00000001f65a57f8 # floor(x^48 / G(x))
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.section .rodata.cst16.mask1, "aM", @progbits, 16
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.align 16
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.Lmask1:
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.octa 0x80808080808080808080808080808080
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.section .rodata.cst16.mask2, "aM", @progbits, 16
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.align 16
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.Lmask2:
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.octa 0x00000000FFFFFFFFFFFFFFFFFFFFFFFF
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.section .rodata.cst16.bswap_mask, "aM", @progbits, 16
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.align 16
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.Lbswap_mask:
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.octa 0x000102030405060708090A0B0C0D0E0F
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.section .rodata.cst32.byteshift_table, "aM", @progbits, 32
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.align 16
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# For 1 <= len <= 15, the 16-byte vector beginning at &byteshift_table[16 - len]
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# is the index vector to shift left by 'len' bytes, and is also {0x80, ...,
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# 0x80} XOR the index vector to shift right by '16 - len' bytes.
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.Lbyteshift_table:
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.byte 0x0, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87
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.byte 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f
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.byte 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7
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.byte 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe , 0x0
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