/* $Id: checksum.S,v 1.10 2001/07/06 13:11:32 gniibe Exp $
*
* 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
*
* SuperH version: Copyright (C) 1999 Niibe Yutaka
*
* 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.
*/
#include <asm/errno.h>
#include <linux/linkage.h>
/*
* computes a partial checksum, e.g. for TCP/UDP fragments
*/
/*
* unsigned int csum_partial(const unsigned char *buf, int len,
* unsigned int sum);
*/
.text
ENTRY(csum_partial)
/*
* 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.
*/
mov r5, r1
mov r4, r0
tst #2, r0 ! Check alignment.
bt 2f ! Jump if alignment is ok.
!
add #-2, r5 ! Alignment uses up two bytes.
cmp/pz r5 !
bt/s 1f ! Jump if we had at least two bytes.
clrt
bra 6f
add #2, r5 ! r5 was < 2. Deal with it.
1:
mov r5, r1 ! Save new len for later use.
mov.w @r4+, r0
extu.w r0, r0
addc r0, r6
bf 2f
add #1, r6
2:
mov #-5, r0
shld r0, r5
tst r5, r5
bt/s 4f ! if it's =0, go to 4f
clrt
.align 2
3:
mov.l @r4+, r0
mov.l @r4+, r2
mov.l @r4+, r3
addc r0, r6
mov.l @r4+, r0
addc r2, r6
mov.l @r4+, r2
addc r3, r6
mov.l @r4+, r3
addc r0, r6
mov.l @r4+, r0
addc r2, r6
mov.l @r4+, r2
addc r3, r6
addc r0, r6
addc r2, r6
movt r0
dt r5
bf/s 3b
cmp/eq #1, r0
! here, we know r5==0
addc r5, r6 ! add carry to r6
4:
mov r1, r0
and #0x1c, r0
tst r0, r0
bt/s 6f
mov r0, r5
shlr2 r5
mov #0, r2
5:
addc r2, r6
mov.l @r4+, r2
movt r0
dt r5
bf/s 5b
cmp/eq #1, r0
addc r2, r6
addc r5, r6 ! r5==0 here, so it means add carry-bit
6:
mov r1, r5
mov #3, r0
and r0, r5
tst r5, r5
bt 9f ! if it's =0 go to 9f
mov #2, r1
cmp/hs r1, r5
bf 7f
mov.w @r4+, r0
extu.w r0, r0
cmp/eq r1, r5
bt/s 8f
clrt
shll16 r0
addc r0, r6
7:
mov.b @r4+, r0
extu.b r0, r0
#ifndef __LITTLE_ENDIAN__
shll8 r0
#endif
8:
addc r0, r6
mov #0, r0
addc r0, r6
9:
rts
mov r6, r0
/*
unsigned int csum_partial_copy_generic (const char *src, char *dst, int len,
int sum, int *src_err_ptr, int *dst_err_ptr)
*/
/*
* Copy from ds while checksumming, otherwise like csum_partial
*
* The macros SRC and DST specify the type of access for the instruction.
* thus we can call a custom exception handler for all access types.
*
* FIXME: could someone double-check whether I haven't mixed up some SRC and
* DST definitions? It's damn hard to trigger all cases. I hope I got
* them all but there's no guarantee.
*/
#define SRC(...) \
9999: __VA_ARGS__ ; \
.section __ex_table, "a"; \
.long 9999b, 6001f ; \
.previous
#define DST(...) \
9999: __VA_ARGS__ ; \
.section __ex_table, "a"; \
.long 9999b, 6002f ; \
.previous
!
! r4: const char *SRC
! r5: char *DST
! r6: int LEN
! r7: int SUM
!
! on stack:
! int *SRC_ERR_PTR
! int *DST_ERR_PTR
!
ENTRY(csum_partial_copy_generic)
mov.l r5,@-r15
mov.l r6,@-r15
mov #3,r0 ! Check src and dest are equally aligned
mov r4,r1
and r0,r1
and r5,r0
cmp/eq r1,r0
bf 3f ! Different alignments, use slow version
tst #1,r0 ! Check dest word aligned
bf 3f ! If not, do it the slow way
mov #2,r0
tst r0,r5 ! Check dest alignment.
bt 2f ! Jump if alignment is ok.
add #-2,r6 ! Alignment uses up two bytes.
cmp/pz r6 ! Jump if we had at least two bytes.
bt/s 1f
clrt
add #2,r6 ! r6 was < 2. Deal with it.
bra 4f
mov r6,r2
3: ! Handle different src and dest alignments.
! This is not common, so simple byte by byte copy will do.
mov r6,r2
shlr r6
tst r6,r6
bt 4f
clrt
.align 2
5:
SRC( mov.b @r4+,r1 )
SRC( mov.b @r4+,r0 )
extu.b r1,r1
DST( mov.b r1,@r5 )
DST( mov.b r0,@(1,r5) )
extu.b r0,r0
add #2,r5
#ifdef __LITTLE_ENDIAN__
shll8 r0
#else
shll8 r1
#endif
or r1,r0
addc r0,r7
movt r0
dt r6
bf/s 5b
cmp/eq #1,r0
mov #0,r0
addc r0, r7
mov r2, r0
tst #1, r0
bt 7f
bra 5f
clrt
! src and dest equally aligned, but to a two byte boundary.
! Handle first two bytes as a special case
.align 2
1:
SRC( mov.w @r4+,r0 )
DST( mov.w r0,@r5 )
add #2,r5
extu.w r0,r0
addc r0,r7
mov #0,r0
addc r0,r7
2:
mov r6,r2
mov #-5,r0
shld r0,r6
tst r6,r6
bt/s 2f
clrt
.align 2
1:
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@r5 )
DST( mov.l r1,@(4,r5) )
addc r1,r7
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@(8,r5) )
DST( mov.l r1,@(12,r5) )
addc r1,r7
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@(16,r5) )
DST( mov.l r1,@(20,r5) )
addc r1,r7
SRC( mov.l @r4+,r0 )
SRC( mov.l @r4+,r1 )
addc r0,r7
DST( mov.l r0,@(24,r5) )
DST( mov.l r1,@(28,r5) )
addc r1,r7
add #32,r5
movt r0
dt r6
bf/s 1b
cmp/eq #1,r0
mov #0,r0
addc r0,r7
2: mov r2,r6
mov #0x1c,r0
and r0,r6
cmp/pl r6
bf/s 4f
clrt
shlr2 r6
3:
SRC( mov.l @r4+,r0 )
addc r0,r7
DST( mov.l r0,@r5 )
add #4,r5
movt r0
dt r6
bf/s 3b
cmp/eq #1,r0
mov #0,r0
addc r0,r7
4: mov r2,r6
mov #3,r0
and r0,r6
cmp/pl r6
bf 7f
mov #2,r1
cmp/hs r1,r6
bf 5f
SRC( mov.w @r4+,r0 )
DST( mov.w r0,@r5 )
extu.w r0,r0
add #2,r5
cmp/eq r1,r6
bt/s 6f
clrt
shll16 r0
addc r0,r7
5:
SRC( mov.b @r4+,r0 )
DST( mov.b r0,@r5 )
extu.b r0,r0
#ifndef __LITTLE_ENDIAN__
shll8 r0
#endif
6: addc r0,r7
mov #0,r0
addc r0,r7
7:
5000:
# Exception handler:
.section .fixup, "ax"
6001:
mov.l @(8,r15),r0 ! src_err_ptr
mov #-EFAULT,r1
mov.l r1,@r0
! zero the complete destination - computing the rest
! is too much work
mov.l @(4,r15),r5 ! dst
mov.l @r15,r6 ! len
mov #0,r7
1: mov.b r7,@r5
dt r6
bf/s 1b
add #1,r5
mov.l 8000f,r0
jmp @r0
nop
.align 2
8000: .long 5000b
6002:
mov.l @(12,r15),r0 ! dst_err_ptr
mov #-EFAULT,r1
mov.l r1,@r0
mov.l 8001f,r0
jmp @r0
nop
.align 2
8001: .long 5000b
.previous
add #8,r15
rts
mov r7,r0
