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| /*
| * 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>
|
| .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)
|
|
