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| /* SPDX-License-Identifier: GPL-2.0-or-later */
| /*
| * INET An implementation of the TCP/IP protocol suite for the LINUX
| * operating system. INET is implemented using the BSD Socket
| * interface as the means of communication with the user level.
| *
| * IP/TCP/UDP checksumming routines
| *
| * Authors: Jorge Cwik, <jorge@laser.satlink.net>
| * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
| * Tom May, <ftom@netcom.com>
| * Pentium Pro/II routines:
| * Alexander Kjeldaas <astor@guardian.no>
| * Finn Arne Gangstad <finnag@guardian.no>
| * Lots of code moved from tcp.c and ip.c; see those files
| * for more names.
| *
| * Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
| * handling.
| * Andi Kleen, add zeroing on error
| * converted to pure assembler
| */
|
| #include <asm/errno.h>
| #include <asm/asm.h>
| #include <asm/export.h>
|
| /*
| * computes a partial checksum, e.g. for TCP/UDP fragments
| */
|
| /*
| unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
| */
|
| .text
| .align 4
| .globl csum_partial
|
| #ifndef CONFIG_X86_USE_PPRO_CHECKSUM
|
| /*
| * Experiments with Ethernet and SLIP connections show that buff
| * is aligned on either a 2-byte or 4-byte boundary. We get at
| * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
| * Fortunately, it is easy to convert 2-byte alignment to 4-byte
| * alignment for the unrolled loop.
| */
| csum_partial:
| pushl %esi
| pushl %ebx
| movl 20(%esp),%eax # Function arg: unsigned int sum
| movl 16(%esp),%ecx # Function arg: int len
| movl 12(%esp),%esi # Function arg: unsigned char *buff
| testl $2, %esi # Check alignment.
| jz 2f # Jump if alignment is ok.
| subl $2, %ecx # Alignment uses up two bytes.
| jae 1f # Jump if we had at least two bytes.
| addl $2, %ecx # ecx was < 2. Deal with it.
| jmp 4f
| 1: movw (%esi), %bx
| addl $2, %esi
| addw %bx, %ax
| adcl $0, %eax
| 2:
| movl %ecx, %edx
| shrl $5, %ecx
| jz 2f
| testl %esi, %esi
| 1: movl (%esi), %ebx
| adcl %ebx, %eax
| movl 4(%esi), %ebx
| adcl %ebx, %eax
| movl 8(%esi), %ebx
| adcl %ebx, %eax
| movl 12(%esi), %ebx
| adcl %ebx, %eax
| movl 16(%esi), %ebx
| adcl %ebx, %eax
| movl 20(%esi), %ebx
| adcl %ebx, %eax
| movl 24(%esi), %ebx
| adcl %ebx, %eax
| movl 28(%esi), %ebx
| adcl %ebx, %eax
| lea 32(%esi), %esi
| dec %ecx
| jne 1b
| adcl $0, %eax
| 2: movl %edx, %ecx
| andl $0x1c, %edx
| je 4f
| shrl $2, %edx # This clears CF
| 3: adcl (%esi), %eax
| lea 4(%esi), %esi
| dec %edx
| jne 3b
| adcl $0, %eax
| 4: andl $3, %ecx
| jz 7f
| cmpl $2, %ecx
| jb 5f
| movw (%esi),%cx
| leal 2(%esi),%esi
| je 6f
| shll $16,%ecx
| 5: movb (%esi),%cl
| 6: addl %ecx,%eax
| adcl $0, %eax
| 7:
| popl %ebx
| popl %esi
| RET
|
| #else
|
| /* Version for PentiumII/PPro */
|
| csum_partial:
| pushl %esi
| pushl %ebx
| movl 20(%esp),%eax # Function arg: unsigned int sum
| movl 16(%esp),%ecx # Function arg: int len
| movl 12(%esp),%esi # Function arg: const unsigned char *buf
|
| testl $2, %esi
| jnz 30f
| 10:
| movl %ecx, %edx
| movl %ecx, %ebx
| andl $0x7c, %ebx
| shrl $7, %ecx
| addl %ebx,%esi
| shrl $2, %ebx
| negl %ebx
| lea 45f(%ebx,%ebx,2), %ebx
| testl %esi, %esi
| jmp *%ebx
|
| # Handle 2-byte-aligned regions
| 20: addw (%esi), %ax
| lea 2(%esi), %esi
| adcl $0, %eax
| jmp 10b
|
| 30: subl $2, %ecx
| ja 20b
| je 32f
| movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
| addl %ebx, %eax
| adcl $0, %eax
| jmp 80f
| 32:
| addw (%esi), %ax # csumming 2 bytes, 2-aligned
| adcl $0, %eax
| jmp 80f
|
| 40:
| addl -128(%esi), %eax
| adcl -124(%esi), %eax
| adcl -120(%esi), %eax
| adcl -116(%esi), %eax
| adcl -112(%esi), %eax
| adcl -108(%esi), %eax
| adcl -104(%esi), %eax
| adcl -100(%esi), %eax
| adcl -96(%esi), %eax
| adcl -92(%esi), %eax
| adcl -88(%esi), %eax
| adcl -84(%esi), %eax
| adcl -80(%esi), %eax
| adcl -76(%esi), %eax
| adcl -72(%esi), %eax
| adcl -68(%esi), %eax
| adcl -64(%esi), %eax
| adcl -60(%esi), %eax
| adcl -56(%esi), %eax
| adcl -52(%esi), %eax
| adcl -48(%esi), %eax
| adcl -44(%esi), %eax
| adcl -40(%esi), %eax
| adcl -36(%esi), %eax
| adcl -32(%esi), %eax
| adcl -28(%esi), %eax
| adcl -24(%esi), %eax
| adcl -20(%esi), %eax
| adcl -16(%esi), %eax
| adcl -12(%esi), %eax
| adcl -8(%esi), %eax
| adcl -4(%esi), %eax
| 45:
| lea 128(%esi), %esi
| adcl $0, %eax
| dec %ecx
| jge 40b
| movl %edx, %ecx
| 50: andl $3, %ecx
| jz 80f
|
| # Handle the last 1-3 bytes without jumping
| notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
| movl $0xffffff,%ebx # by the shll and shrl instructions
| shll $3,%ecx
| shrl %cl,%ebx
| andl -128(%esi),%ebx # esi is 4-aligned so should be ok
| addl %ebx,%eax
| adcl $0,%eax
| 80:
| popl %ebx
| popl %esi
| RET
|
| #endif
| EXPORT_SYMBOL(csum_partial)
|
|
