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139 lines
2.9 KiB
139 lines
2.9 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* linux/arch/arm/lib/csumpartial.S |
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* |
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* Copyright (C) 1995-1998 Russell King |
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*/ |
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#include <linux/linkage.h> |
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#include <asm/assembler.h> |
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.text |
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/* |
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* Function: __u32 csum_partial(const char *src, int len, __u32 sum) |
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* Params : r0 = buffer, r1 = len, r2 = checksum |
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* Returns : r0 = new checksum |
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*/ |
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buf .req r0 |
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len .req r1 |
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sum .req r2 |
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td0 .req r3 |
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td1 .req r4 @ save before use |
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td2 .req r5 @ save before use |
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td3 .req lr |
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.Lzero: mov r0, sum |
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add sp, sp, #4 |
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ldr pc, [sp], #4 |
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/* |
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* Handle 0 to 7 bytes, with any alignment of source and |
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* destination pointers. Note that when we get here, C = 0 |
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*/ |
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.Lless8: teq len, #0 @ check for zero count |
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beq .Lzero |
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/* we must have at least one byte. */ |
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tst buf, #1 @ odd address? |
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movne sum, sum, ror #8 |
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ldrbne td0, [buf], #1 |
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subne len, len, #1 |
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adcsne sum, sum, td0, put_byte_1 |
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.Lless4: tst len, #6 |
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beq .Lless8_byte |
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/* we are now half-word aligned */ |
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.Lless8_wordlp: |
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#if __LINUX_ARM_ARCH__ >= 4 |
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ldrh td0, [buf], #2 |
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sub len, len, #2 |
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#else |
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ldrb td0, [buf], #1 |
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ldrb td3, [buf], #1 |
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sub len, len, #2 |
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#ifndef __ARMEB__ |
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orr td0, td0, td3, lsl #8 |
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#else |
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orr td0, td3, td0, lsl #8 |
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#endif |
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#endif |
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adcs sum, sum, td0 |
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tst len, #6 |
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bne .Lless8_wordlp |
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.Lless8_byte: tst len, #1 @ odd number of bytes |
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ldrbne td0, [buf], #1 @ include last byte |
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adcsne sum, sum, td0, put_byte_0 @ update checksum |
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.Ldone: adc r0, sum, #0 @ collect up the last carry |
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ldr td0, [sp], #4 |
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tst td0, #1 @ check buffer alignment |
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movne r0, r0, ror #8 @ rotate checksum by 8 bits |
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ldr pc, [sp], #4 @ return |
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.Lnot_aligned: tst buf, #1 @ odd address |
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ldrbne td0, [buf], #1 @ make even |
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subne len, len, #1 |
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adcsne sum, sum, td0, put_byte_1 @ update checksum |
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tst buf, #2 @ 32-bit aligned? |
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#if __LINUX_ARM_ARCH__ >= 4 |
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ldrhne td0, [buf], #2 @ make 32-bit aligned |
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subne len, len, #2 |
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#else |
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ldrbne td0, [buf], #1 |
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ldrbne ip, [buf], #1 |
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subne len, len, #2 |
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#ifndef __ARMEB__ |
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orrne td0, td0, ip, lsl #8 |
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#else |
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orrne td0, ip, td0, lsl #8 |
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#endif |
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#endif |
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adcsne sum, sum, td0 @ update checksum |
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ret lr |
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ENTRY(csum_partial) |
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stmfd sp!, {buf, lr} |
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cmp len, #8 @ Ensure that we have at least |
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blo .Lless8 @ 8 bytes to copy. |
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tst buf, #1 |
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movne sum, sum, ror #8 |
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adds sum, sum, #0 @ C = 0 |
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tst buf, #3 @ Test destination alignment |
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blne .Lnot_aligned @ align destination, return here |
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1: bics ip, len, #31 |
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beq 3f |
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stmfd sp!, {r4 - r5} |
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2: ldmia buf!, {td0, td1, td2, td3} |
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adcs sum, sum, td0 |
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adcs sum, sum, td1 |
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adcs sum, sum, td2 |
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adcs sum, sum, td3 |
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ldmia buf!, {td0, td1, td2, td3} |
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adcs sum, sum, td0 |
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adcs sum, sum, td1 |
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adcs sum, sum, td2 |
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adcs sum, sum, td3 |
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sub ip, ip, #32 |
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teq ip, #0 |
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bne 2b |
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ldmfd sp!, {r4 - r5} |
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3: tst len, #0x1c @ should not change C |
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beq .Lless4 |
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4: ldr td0, [buf], #4 |
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sub len, len, #4 |
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adcs sum, sum, td0 |
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tst len, #0x1c |
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bne 4b |
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b .Lless4 |
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ENDPROC(csum_partial)
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