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[arm] Add optimised TCP/IP checksumming for 64-bit ARM
Signed-off-by: Michael Brown <mcb30@ipxe.org>
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/* | ||
* Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>. | ||
* | ||
* This program is free software; you can redistribute it and/or | ||
* modify it under the terms of the GNU General Public License as | ||
* published by the Free Software Foundation; either version 2 of the | ||
* License, or (at your option) any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, but | ||
* WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
* General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program; if not, write to the Free Software | ||
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | ||
* 02110-1301, USA. | ||
* | ||
* You can also choose to distribute this program under the terms of | ||
* the Unmodified Binary Distribution Licence (as given in the file | ||
* COPYING.UBDL), provided that you have satisfied its requirements. | ||
*/ | ||
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); | ||
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/** @file | ||
* | ||
* TCP/IP checksum | ||
* | ||
*/ | ||
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#include <strings.h> | ||
#include <ipxe/tcpip.h> | ||
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/** Alignment used by main checksumming loop */ | ||
#define TCPIP_CHKSUM_ALIGN 16 | ||
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/** Number of steps in each iteration of the unrolled main checksumming loop */ | ||
#define TCPIP_CHKSUM_UNROLL 4 | ||
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/** | ||
* Calculate continued TCP/IP checkum | ||
* | ||
* @v sum Checksum of already-summed data, in network byte order | ||
* @v data Data buffer | ||
* @v len Length of data buffer | ||
* @ret sum Updated checksum, in network byte order | ||
*/ | ||
uint16_t tcpip_continue_chksum ( uint16_t sum, const void *data, | ||
size_t len ) { | ||
intptr_t start; | ||
intptr_t end; | ||
intptr_t mid; | ||
unsigned int pre; | ||
unsigned int post; | ||
unsigned int first; | ||
uint64_t discard_low; | ||
uint64_t discard_high; | ||
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/* Avoid potentially undefined shift operation */ | ||
if ( len == 0 ) | ||
return sum; | ||
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/* Find maximally-aligned midpoint. For short blocks of data, | ||
* this may be aligned to fewer than 16 bytes. | ||
*/ | ||
start = ( ( intptr_t ) data ); | ||
end = ( start + len ); | ||
mid = ( end & | ||
~( ( ~( 1UL << 63 ) ) >> ( 64 - flsl ( start ^ end ) ) ) ); | ||
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/* Calculate pre- and post-alignment lengths */ | ||
pre = ( ( mid - start ) & ( TCPIP_CHKSUM_ALIGN - 1 ) ); | ||
post = ( ( end - mid ) & ( TCPIP_CHKSUM_ALIGN - 1 ) ); | ||
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/* Calculate number of steps in first iteration of unrolled loop */ | ||
first = ( ( ( len - pre - post ) / TCPIP_CHKSUM_ALIGN ) & | ||
( TCPIP_CHKSUM_UNROLL - 1 ) ); | ||
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/* Calculate checksum */ | ||
__asm__ ( /* Invert sum */ | ||
"eor %w0, %w0, #0xffff\n\t" | ||
/* Clear carry flag */ | ||
"cmn xzr, xzr\n\t" | ||
/* Byteswap and sum pre-alignment byte, if applicable */ | ||
"tbz %w4, #0, 1f\n\t" | ||
"ldrb %w2, [%1], #1\n\t" | ||
"rev16 %w0, %w0\n\t" | ||
"rev16 %w2, %w2\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Sum pre-alignment halfword, if applicable */ | ||
"tbz %w4, #1, 1f\n\t" | ||
"ldrh %w2, [%1], #2\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Sum pre-alignment word, if applicable */ | ||
"tbz %w4, #2, 1f\n\t" | ||
"ldr %w2, [%1], #4\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Sum pre-alignment doubleword, if applicable */ | ||
"tbz %w4, #3, 1f\n\t" | ||
"ldr %2, [%1], #8\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Jump into unrolled (x4) main loop */ | ||
"adr %2, 2f\n\t" | ||
"sub %2, %2, %5, lsl #3\n\t" | ||
"sub %2, %2, %5, lsl #2\n\t" | ||
"br %2\n\t" | ||
"\n1:\n\t" | ||
"ldp %2, %3, [%1], #16\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"adcs %0, %0, %3\n\t" | ||
"ldp %2, %3, [%1], #16\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"adcs %0, %0, %3\n\t" | ||
"ldp %2, %3, [%1], #16\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"adcs %0, %0, %3\n\t" | ||
"ldp %2, %3, [%1], #16\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"adcs %0, %0, %3\n\t" | ||
"\n2:\n\t" | ||
"sub %2, %1, %6\n\t" | ||
"cbnz %2, 1b\n\t" | ||
/* Sum post-alignment doubleword, if applicable */ | ||
"tbz %w7, #3, 1f\n\t" | ||
"ldr %2, [%1], #8\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Sum post-alignment word, if applicable */ | ||
"tbz %w7, #2, 1f\n\t" | ||
"ldr %w2, [%1], #4\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Sum post-alignment halfword, if applicable */ | ||
"tbz %w7, #1, 1f\n\t" | ||
"ldrh %w2, [%1], #2\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Sum post-alignment byte, if applicable */ | ||
"tbz %w7, #0, 1f\n\t" | ||
"ldrb %w2, [%1], #1\n\t" | ||
"adcs %0, %0, %2\n\t" | ||
"\n1:\n\t" | ||
/* Fold down to a uint32_t plus carry flag */ | ||
"lsr %2, %0, #32\n\t" | ||
"adcs %w0, %w0, %w2\n\t" | ||
/* Fold down to a uint16_t plus carry in bit 16 */ | ||
"ubfm %2, %0, #0, #15\n\t" | ||
"ubfm %3, %0, #16, #31\n\t" | ||
"adc %w0, %w2, %w3\n\t" | ||
/* Fold down to a uint16_t */ | ||
"tbz %w0, #16, 1f\n\t" | ||
"mov %w2, #0xffff\n\t" | ||
"sub %w0, %w0, %w2\n\t" | ||
"tbz %w0, #16, 1f\n\t" | ||
"sub %w0, %w0, %w2\n\t" | ||
"\n1:\n\t" | ||
/* Byteswap back, if applicable */ | ||
"tbz %w4, #0, 1f\n\t" | ||
"rev16 %w0, %w0\n\t" | ||
"\n1:\n\t" | ||
/* Invert sum */ | ||
"eor %w0, %w0, #0xffff\n\t" | ||
: "+r" ( sum ), "+r" ( data ), "=&r" ( discard_low ), | ||
"=&r" ( discard_high ) | ||
: "r" ( pre ), "r" ( first ), "r" ( end - post ), | ||
"r" ( post ) | ||
: "cc" ); | ||
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return sum; | ||
} |
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#ifndef _BITS_TCPIP_H | ||
#define _BITS_TCPIP_H | ||
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/** @file | ||
* | ||
* Transport-network layer interface | ||
* | ||
*/ | ||
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); | ||
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extern uint16_t tcpip_continue_chksum ( uint16_t sum, const void *data, | ||
size_t len ); | ||
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#endif /* _BITS_TCPIP_H */ |