1/* 2 * linux/arch/arm/lib/csumpartial.S 3 * 4 * Copyright (C) 1995-1998 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10#include <linux/linkage.h> 11#include <asm/assembler.h> 12 13 .text 14 15/* 16 * Function: __u32 csum_partial(const char *src, int len, __u32 sum) 17 * Params : r0 = buffer, r1 = len, r2 = checksum 18 * Returns : r0 = new checksum 19 */ 20 21buf .req r0 22len .req r1 23sum .req r2 24td0 .req r3 25td1 .req r4 @ save before use 26td2 .req r5 @ save before use 27td3 .req lr 28 29.Lzero: mov r0, sum 30 add sp, sp, #4 31 ldr pc, [sp], #4 32 33 /* 34 * Handle 0 to 7 bytes, with any alignment of source and 35 * destination pointers. Note that when we get here, C = 0 36 */ 37.Lless8: teq len, #0 @ check for zero count 38 beq .Lzero 39 40 /* we must have at least one byte. */ 41 tst buf, #1 @ odd address? 42 movne sum, sum, ror #8 43 ldrneb td0, [buf], #1 44 subne len, len, #1 45 adcnes sum, sum, td0, put_byte_1 46 47.Lless4: tst len, #6 48 beq .Lless8_byte 49 50 /* we are now half-word aligned */ 51 52.Lless8_wordlp: 53#if __LINUX_ARM_ARCH__ >= 4 54 ldrh td0, [buf], #2 55 sub len, len, #2 56#else 57 ldrb td0, [buf], #1 58 ldrb td3, [buf], #1 59 sub len, len, #2 60#ifndef __ARMEB__ 61 orr td0, td0, td3, lsl #8 62#else 63 orr td0, td3, td0, lsl #8 64#endif 65#endif 66 adcs sum, sum, td0 67 tst len, #6 68 bne .Lless8_wordlp 69 70.Lless8_byte: tst len, #1 @ odd number of bytes 71 ldrneb td0, [buf], #1 @ include last byte 72 adcnes sum, sum, td0, put_byte_0 @ update checksum 73 74.Ldone: adc r0, sum, #0 @ collect up the last carry 75 ldr td0, [sp], #4 76 tst td0, #1 @ check buffer alignment 77 movne r0, r0, ror #8 @ rotate checksum by 8 bits 78 ldr pc, [sp], #4 @ return 79 80.Lnot_aligned: tst buf, #1 @ odd address 81 ldrneb td0, [buf], #1 @ make even 82 subne len, len, #1 83 adcnes sum, sum, td0, put_byte_1 @ update checksum 84 85 tst buf, #2 @ 32-bit aligned? 86#if __LINUX_ARM_ARCH__ >= 4 87 ldrneh td0, [buf], #2 @ make 32-bit aligned 88 subne len, len, #2 89#else 90 ldrneb td0, [buf], #1 91 ldrneb ip, [buf], #1 92 subne len, len, #2 93#ifndef __ARMEB__ 94 orrne td0, td0, ip, lsl #8 95#else 96 orrne td0, ip, td0, lsl #8 97#endif 98#endif 99 adcnes sum, sum, td0 @ update checksum 100 ret lr 101 102ENTRY(csum_partial) 103 stmfd sp!, {buf, lr} 104 cmp len, #8 @ Ensure that we have at least 105 blo .Lless8 @ 8 bytes to copy. 106 107 tst buf, #1 108 movne sum, sum, ror #8 109 110 adds sum, sum, #0 @ C = 0 111 tst buf, #3 @ Test destination alignment 112 blne .Lnot_aligned @ align destination, return here 113 1141: bics ip, len, #31 115 beq 3f 116 117 stmfd sp!, {r4 - r5} 1182: ldmia buf!, {td0, td1, td2, td3} 119 adcs sum, sum, td0 120 adcs sum, sum, td1 121 adcs sum, sum, td2 122 adcs sum, sum, td3 123 ldmia buf!, {td0, td1, td2, td3} 124 adcs sum, sum, td0 125 adcs sum, sum, td1 126 adcs sum, sum, td2 127 adcs sum, sum, td3 128 sub ip, ip, #32 129 teq ip, #0 130 bne 2b 131 ldmfd sp!, {r4 - r5} 132 1333: tst len, #0x1c @ should not change C 134 beq .Lless4 135 1364: ldr td0, [buf], #4 137 sub len, len, #4 138 adcs sum, sum, td0 139 tst len, #0x1c 140 bne 4b 141 b .Lless4 142ENDPROC(csum_partial) 143