mirror of
https://github.com/torvalds/linux.git
synced 2024-12-23 19:31:53 +00:00
145 lines
3.1 KiB
ArmAsm
145 lines
3.1 KiB
ArmAsm
/*
|
|
* linux/arch/arm/lib/csumpartial.S
|
|
*
|
|
* Copyright (C) 1995-1998 Russell King
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
#include <linux/linkage.h>
|
|
#include <asm/assembler.h>
|
|
#include <asm/export.h>
|
|
|
|
.text
|
|
|
|
/*
|
|
* Function: __u32 csum_partial(const char *src, int len, __u32 sum)
|
|
* Params : r0 = buffer, r1 = len, r2 = checksum
|
|
* Returns : r0 = new checksum
|
|
*/
|
|
|
|
buf .req r0
|
|
len .req r1
|
|
sum .req r2
|
|
td0 .req r3
|
|
td1 .req r4 @ save before use
|
|
td2 .req r5 @ save before use
|
|
td3 .req lr
|
|
|
|
.Lzero: mov r0, sum
|
|
add sp, sp, #4
|
|
ldr pc, [sp], #4
|
|
|
|
/*
|
|
* Handle 0 to 7 bytes, with any alignment of source and
|
|
* destination pointers. Note that when we get here, C = 0
|
|
*/
|
|
.Lless8: teq len, #0 @ check for zero count
|
|
beq .Lzero
|
|
|
|
/* we must have at least one byte. */
|
|
tst buf, #1 @ odd address?
|
|
movne sum, sum, ror #8
|
|
ldrneb td0, [buf], #1
|
|
subne len, len, #1
|
|
adcnes sum, sum, td0, put_byte_1
|
|
|
|
.Lless4: tst len, #6
|
|
beq .Lless8_byte
|
|
|
|
/* we are now half-word aligned */
|
|
|
|
.Lless8_wordlp:
|
|
#if __LINUX_ARM_ARCH__ >= 4
|
|
ldrh td0, [buf], #2
|
|
sub len, len, #2
|
|
#else
|
|
ldrb td0, [buf], #1
|
|
ldrb td3, [buf], #1
|
|
sub len, len, #2
|
|
#ifndef __ARMEB__
|
|
orr td0, td0, td3, lsl #8
|
|
#else
|
|
orr td0, td3, td0, lsl #8
|
|
#endif
|
|
#endif
|
|
adcs sum, sum, td0
|
|
tst len, #6
|
|
bne .Lless8_wordlp
|
|
|
|
.Lless8_byte: tst len, #1 @ odd number of bytes
|
|
ldrneb td0, [buf], #1 @ include last byte
|
|
adcnes sum, sum, td0, put_byte_0 @ update checksum
|
|
|
|
.Ldone: adc r0, sum, #0 @ collect up the last carry
|
|
ldr td0, [sp], #4
|
|
tst td0, #1 @ check buffer alignment
|
|
movne r0, r0, ror #8 @ rotate checksum by 8 bits
|
|
ldr pc, [sp], #4 @ return
|
|
|
|
.Lnot_aligned: tst buf, #1 @ odd address
|
|
ldrneb td0, [buf], #1 @ make even
|
|
subne len, len, #1
|
|
adcnes sum, sum, td0, put_byte_1 @ update checksum
|
|
|
|
tst buf, #2 @ 32-bit aligned?
|
|
#if __LINUX_ARM_ARCH__ >= 4
|
|
ldrneh td0, [buf], #2 @ make 32-bit aligned
|
|
subne len, len, #2
|
|
#else
|
|
ldrneb td0, [buf], #1
|
|
ldrneb ip, [buf], #1
|
|
subne len, len, #2
|
|
#ifndef __ARMEB__
|
|
orrne td0, td0, ip, lsl #8
|
|
#else
|
|
orrne td0, ip, td0, lsl #8
|
|
#endif
|
|
#endif
|
|
adcnes sum, sum, td0 @ update checksum
|
|
ret lr
|
|
|
|
ENTRY(csum_partial)
|
|
stmfd sp!, {buf, lr}
|
|
cmp len, #8 @ Ensure that we have at least
|
|
blo .Lless8 @ 8 bytes to copy.
|
|
|
|
tst buf, #1
|
|
movne sum, sum, ror #8
|
|
|
|
adds sum, sum, #0 @ C = 0
|
|
tst buf, #3 @ Test destination alignment
|
|
blne .Lnot_aligned @ align destination, return here
|
|
|
|
1: bics ip, len, #31
|
|
beq 3f
|
|
|
|
stmfd sp!, {r4 - r5}
|
|
2: ldmia buf!, {td0, td1, td2, td3}
|
|
adcs sum, sum, td0
|
|
adcs sum, sum, td1
|
|
adcs sum, sum, td2
|
|
adcs sum, sum, td3
|
|
ldmia buf!, {td0, td1, td2, td3}
|
|
adcs sum, sum, td0
|
|
adcs sum, sum, td1
|
|
adcs sum, sum, td2
|
|
adcs sum, sum, td3
|
|
sub ip, ip, #32
|
|
teq ip, #0
|
|
bne 2b
|
|
ldmfd sp!, {r4 - r5}
|
|
|
|
3: tst len, #0x1c @ should not change C
|
|
beq .Lless4
|
|
|
|
4: ldr td0, [buf], #4
|
|
sub len, len, #4
|
|
adcs sum, sum, td0
|
|
tst len, #0x1c
|
|
bne 4b
|
|
b .Lless4
|
|
ENDPROC(csum_partial)
|
|
EXPORT_SYMBOL(csum_partial)
|