| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
| 21 | buf .req r0 |
| 22 | len .req r1 |
| 23 | sum .req r2 |
| 24 | td0 .req r3 |
| 25 | td1 .req r4 @ save before use |
| 26 | td2 .req r5 @ save before use |
| 27 | td3 .req lr |
| 28 | |
| 29 | .zero: 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 | .less8: teq len, #0 @ check for zero count |
| 38 | beq .zero |
| 39 | |
| 40 | /* we must have at least one byte. */ |
| 41 | tst buf, #1 @ odd address? |
| 42 | ldrneb td0, [buf], #1 |
| 43 | subne len, len, #1 |
| 44 | adcnes sum, sum, td0, put_byte_1 |
| 45 | |
| 46 | .less4: tst len, #6 |
| 47 | beq .less8_byte |
| 48 | |
| 49 | /* we are now half-word aligned */ |
| 50 | |
| 51 | .less8_wordlp: |
| 52 | #if __LINUX_ARM_ARCH__ >= 4 |
| 53 | ldrh td0, [buf], #2 |
| 54 | sub len, len, #2 |
| 55 | #else |
| 56 | ldrb td0, [buf], #1 |
| 57 | ldrb td3, [buf], #1 |
| 58 | sub len, len, #2 |
| 59 | #ifndef __ARMEB__ |
| 60 | orr td0, td0, td3, lsl #8 |
| 61 | #else |
| 62 | orr td0, td3, td0, lsl #8 |
| 63 | #endif |
| 64 | #endif |
| 65 | adcs sum, sum, td0 |
| 66 | tst len, #6 |
| 67 | bne .less8_wordlp |
| 68 | |
| 69 | .less8_byte: tst len, #1 @ odd number of bytes |
| 70 | ldrneb td0, [buf], #1 @ include last byte |
| 71 | adcnes sum, sum, td0, put_byte_0 @ update checksum |
| 72 | |
| 73 | .done: adc r0, sum, #0 @ collect up the last carry |
| 74 | ldr td0, [sp], #4 |
| 75 | tst td0, #1 @ check buffer alignment |
| 76 | movne r0, r0, ror #8 @ rotate checksum by 8 bits |
| 77 | ldr pc, [sp], #4 @ return |
| 78 | |
| 79 | .not_aligned: tst buf, #1 @ odd address |
| 80 | ldrneb td0, [buf], #1 @ make even |
| 81 | subne len, len, #1 |
| 82 | adcnes sum, sum, td0, put_byte_1 @ update checksum |
| 83 | |
| 84 | tst buf, #2 @ 32-bit aligned? |
| 85 | #if __LINUX_ARM_ARCH__ >= 4 |
| 86 | ldrneh td0, [buf], #2 @ make 32-bit aligned |
| 87 | subne len, len, #2 |
| 88 | #else |
| 89 | ldrneb td0, [buf], #1 |
| 90 | ldrneb ip, [buf], #1 |
| 91 | subne len, len, #2 |
| 92 | #ifndef __ARMEB__ |
| 93 | orrne td0, td0, ip, lsl #8 |
| 94 | #else |
| 95 | orrne td0, ip, td0, lsl #8 |
| 96 | #endif |
| 97 | #endif |
| 98 | adcnes sum, sum, td0 @ update checksum |
| 99 | mov pc, lr |
| 100 | |
| 101 | ENTRY(csum_partial) |
| 102 | stmfd sp!, {buf, lr} |
| 103 | cmp len, #8 @ Ensure that we have at least |
| 104 | blo .less8 @ 8 bytes to copy. |
| 105 | |
| 106 | adds sum, sum, #0 @ C = 0 |
| 107 | tst buf, #3 @ Test destination alignment |
| 108 | blne .not_aligned @ aligh destination, return here |
| 109 | |
| 110 | 1: bics ip, len, #31 |
| 111 | beq 3f |
| 112 | |
| 113 | stmfd sp!, {r4 - r5} |
| 114 | 2: ldmia buf!, {td0, td1, td2, td3} |
| 115 | adcs sum, sum, td0 |
| 116 | adcs sum, sum, td1 |
| 117 | adcs sum, sum, td2 |
| 118 | adcs sum, sum, td3 |
| 119 | ldmia buf!, {td0, td1, td2, td3} |
| 120 | adcs sum, sum, td0 |
| 121 | adcs sum, sum, td1 |
| 122 | adcs sum, sum, td2 |
| 123 | adcs sum, sum, td3 |
| 124 | sub ip, ip, #32 |
| 125 | teq ip, #0 |
| 126 | bne 2b |
| 127 | ldmfd sp!, {r4 - r5} |
| 128 | |
| 129 | 3: tst len, #0x1c @ should not change C |
| 130 | beq .less4 |
| 131 | |
| 132 | 4: ldr td0, [buf], #4 |
| 133 | sub len, len, #4 |
| 134 | adcs sum, sum, td0 |
| 135 | tst len, #0x1c |
| 136 | bne 4b |
| 137 | b .less4 |