1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * linux/arch/arm/lib/csumpartial.S 4 * 5 * Copyright (C) 1995-1998 Russell King 6 */ 7 #include <linux/linkage.h> 8 #include <asm/assembler.h> 9 10 .text 11 12 /* 13 * Function: __u32 csum_partial(const char *src, int len, __u32 sum) 14 * Params : r0 = buffer, r1 = len, r2 = checksum 15 * Returns : r0 = new checksum 16 */ 17 18 buf .req r0 19 len .req r1 20 sum .req r2 21 td0 .req r3 22 td1 .req r4 @ save before use 23 td2 .req r5 @ save before use 24 td3 .req lr 25 26 .Lzero: mov r0, sum 27 add sp, sp, #4 28 ldr pc, [sp], #4 29 30 /* 31 * Handle 0 to 7 bytes, with any alignment of source and 32 * destination pointers. Note that when we get here, C = 0 33 */ 34 .Lless8: teq len, #0 @ check for zero count 35 beq .Lzero 36 37 /* we must have at least one byte. */ 38 tst buf, #1 @ odd address? 39 movne sum, sum, ror #8 40 ldrbne td0, [buf], #1 41 subne len, len, #1 42 adcsne sum, sum, td0, put_byte_1 43 44 .Lless4: tst len, #6 45 beq .Lless8_byte 46 47 /* we are now half-word aligned */ 48 49 .Lless8_wordlp: 50 #if __LINUX_ARM_ARCH__ >= 4 51 ldrh td0, [buf], #2 52 sub len, len, #2 53 #else 54 ldrb td0, [buf], #1 55 ldrb td3, [buf], #1 56 sub len, len, #2 57 #ifndef __ARMEB__ 58 orr td0, td0, td3, lsl #8 59 #else 60 orr td0, td3, td0, lsl #8 61 #endif 62 #endif 63 adcs sum, sum, td0 64 tst len, #6 65 bne .Lless8_wordlp 66 67 .Lless8_byte: tst len, #1 @ odd number of bytes 68 ldrbne td0, [buf], #1 @ include last byte 69 adcsne sum, sum, td0, put_byte_0 @ update checksum 70 71 .Ldone: adc r0, sum, #0 @ collect up the last carry 72 ldr td0, [sp], #4 73 tst td0, #1 @ check buffer alignment 74 movne r0, r0, ror #8 @ rotate checksum by 8 bits 75 ldr pc, [sp], #4 @ return 76 77 .Lnot_aligned: tst buf, #1 @ odd address 78 ldrbne td0, [buf], #1 @ make even 79 subne len, len, #1 80 adcsne sum, sum, td0, put_byte_1 @ update checksum 81 82 tst buf, #2 @ 32-bit aligned? 83 #if __LINUX_ARM_ARCH__ >= 4 84 ldrhne td0, [buf], #2 @ make 32-bit aligned 85 subne len, len, #2 86 #else 87 ldrbne td0, [buf], #1 88 ldrbne ip, [buf], #1 89 subne len, len, #2 90 #ifndef __ARMEB__ 91 orrne td0, td0, ip, lsl #8 92 #else 93 orrne td0, ip, td0, lsl #8 94 #endif 95 #endif 96 adcsne sum, sum, td0 @ update checksum 97 ret lr 98 99 ENTRY(csum_partial) 100 stmfd sp!, {buf, lr} 101 cmp len, #8 @ Ensure that we have at least 102 blo .Lless8 @ 8 bytes to copy. 103 104 tst buf, #1 105 movne sum, sum, ror #8 106 107 adds sum, sum, #0 @ C = 0 108 tst buf, #3 @ Test destination alignment 109 blne .Lnot_aligned @ align destination, return here 110 111 1: bics ip, len, #31 112 beq 3f 113 114 stmfd sp!, {r4 - r5} 115 2: ldmia buf!, {td0, td1, td2, td3} 116 adcs sum, sum, td0 117 adcs sum, sum, td1 118 adcs sum, sum, td2 119 adcs sum, sum, td3 120 ldmia buf!, {td0, td1, td2, td3} 121 adcs sum, sum, td0 122 adcs sum, sum, td1 123 adcs sum, sum, td2 124 adcs sum, sum, td3 125 sub ip, ip, #32 126 teq ip, #0 127 bne 2b 128 ldmfd sp!, {r4 - r5} 129 130 3: tst len, #0x1c @ should not change C 131 beq .Lless4 132 133 4: ldr td0, [buf], #4 134 sub len, len, #4 135 adcs sum, sum, td0 136 tst len, #0x1c 137 bne 4b 138 b .Lless4 139 ENDPROC(csum_partial) 140