219 lines
4.8 KiB
ArmAsm
219 lines
4.8 KiB
ArmAsm
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* IP/TCP/UDP checksumming routines
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*
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* Authors: Jorge Cwik, <jorge@laser.satlink.net>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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* Tom May, <ftom@netcom.com>
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* Pentium Pro/II routines:
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* Alexander Kjeldaas <astor@guardian.no>
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* Finn Arne Gangstad <finnag@guardian.no>
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* Lots of code moved from tcp.c and ip.c; see those files
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* for more names.
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*
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* Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
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* handling.
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* Andi Kleen, add zeroing on error
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* converted to pure assembler
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/errno.h>
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#include <asm/asm.h>
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#include <asm/export.h>
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/*
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* computes a partial checksum, e.g. for TCP/UDP fragments
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*/
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/*
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unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
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*/
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.text
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.align 4
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.globl csum_partial
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#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
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/*
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* Experiments with Ethernet and SLIP connections show that buff
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* is aligned on either a 2-byte or 4-byte boundary. We get at
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* least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
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* Fortunately, it is easy to convert 2-byte alignment to 4-byte
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* alignment for the unrolled loop.
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*/
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csum_partial:
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pushl %esi
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pushl %ebx
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movl 20(%esp),%eax # Function arg: unsigned int sum
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movl 16(%esp),%ecx # Function arg: int len
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movl 12(%esp),%esi # Function arg: unsigned char *buff
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testl $2, %esi # Check alignment.
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jz 2f # Jump if alignment is ok.
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subl $2, %ecx # Alignment uses up two bytes.
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jae 1f # Jump if we had at least two bytes.
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addl $2, %ecx # ecx was < 2. Deal with it.
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jmp 4f
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1: movw (%esi), %bx
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addl $2, %esi
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addw %bx, %ax
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adcl $0, %eax
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2:
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movl %ecx, %edx
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shrl $5, %ecx
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jz 2f
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testl %esi, %esi
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1: movl (%esi), %ebx
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adcl %ebx, %eax
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movl 4(%esi), %ebx
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adcl %ebx, %eax
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movl 8(%esi), %ebx
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adcl %ebx, %eax
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movl 12(%esi), %ebx
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adcl %ebx, %eax
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movl 16(%esi), %ebx
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adcl %ebx, %eax
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movl 20(%esi), %ebx
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adcl %ebx, %eax
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movl 24(%esi), %ebx
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adcl %ebx, %eax
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movl 28(%esi), %ebx
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adcl %ebx, %eax
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lea 32(%esi), %esi
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dec %ecx
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jne 1b
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adcl $0, %eax
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2: movl %edx, %ecx
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andl $0x1c, %edx
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je 4f
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shrl $2, %edx # This clears CF
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3: adcl (%esi), %eax
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lea 4(%esi), %esi
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dec %edx
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jne 3b
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adcl $0, %eax
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4: andl $3, %ecx
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jz 7f
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cmpl $2, %ecx
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jb 5f
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movw (%esi),%cx
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leal 2(%esi),%esi
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je 6f
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shll $16,%ecx
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5: movb (%esi),%cl
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6: addl %ecx,%eax
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adcl $0, %eax
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7:
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popl %ebx
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popl %esi
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ret
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#else
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/* Version for PentiumII/PPro */
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csum_partial:
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pushl %esi
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pushl %ebx
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movl 20(%esp),%eax # Function arg: unsigned int sum
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movl 16(%esp),%ecx # Function arg: int len
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movl 12(%esp),%esi # Function arg: const unsigned char *buf
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testl $2, %esi
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jnz 30f
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10:
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movl %ecx, %edx
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movl %ecx, %ebx
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andl $0x7c, %ebx
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shrl $7, %ecx
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addl %ebx,%esi
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shrl $2, %ebx
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negl %ebx
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lea 45f(%ebx,%ebx,2), %ebx
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testl %esi, %esi
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jmp *%ebx
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# Handle 2-byte-aligned regions
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20: addw (%esi), %ax
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lea 2(%esi), %esi
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adcl $0, %eax
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jmp 10b
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30: subl $2, %ecx
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ja 20b
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je 32f
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movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
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addl %ebx, %eax
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adcl $0, %eax
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jmp 80f
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32:
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addw (%esi), %ax # csumming 2 bytes, 2-aligned
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adcl $0, %eax
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jmp 80f
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40:
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addl -128(%esi), %eax
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adcl -124(%esi), %eax
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adcl -120(%esi), %eax
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adcl -116(%esi), %eax
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adcl -112(%esi), %eax
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adcl -108(%esi), %eax
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adcl -104(%esi), %eax
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adcl -100(%esi), %eax
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adcl -96(%esi), %eax
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adcl -92(%esi), %eax
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adcl -88(%esi), %eax
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adcl -84(%esi), %eax
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adcl -80(%esi), %eax
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adcl -76(%esi), %eax
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adcl -72(%esi), %eax
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adcl -68(%esi), %eax
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adcl -64(%esi), %eax
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adcl -60(%esi), %eax
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adcl -56(%esi), %eax
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adcl -52(%esi), %eax
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adcl -48(%esi), %eax
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adcl -44(%esi), %eax
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adcl -40(%esi), %eax
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adcl -36(%esi), %eax
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adcl -32(%esi), %eax
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adcl -28(%esi), %eax
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adcl -24(%esi), %eax
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adcl -20(%esi), %eax
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adcl -16(%esi), %eax
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adcl -12(%esi), %eax
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adcl -8(%esi), %eax
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adcl -4(%esi), %eax
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45:
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lea 128(%esi), %esi
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adcl $0, %eax
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dec %ecx
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jge 40b
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movl %edx, %ecx
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50: andl $3, %ecx
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jz 80f
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# Handle the last 1-3 bytes without jumping
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notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
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movl $0xffffff,%ebx # by the shll and shrl instructions
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shll $3,%ecx
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shrl %cl,%ebx
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andl -128(%esi),%ebx # esi is 4-aligned so should be ok
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addl %ebx,%eax
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adcl $0,%eax
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80:
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popl %ebx
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popl %esi
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ret
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#endif
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EXPORT_SYMBOL(csum_partial)
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