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Diffstat (limited to 'arch/mn10300/lib/do_csum.S')
| -rw-r--r-- | arch/mn10300/lib/do_csum.S | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/arch/mn10300/lib/do_csum.S b/arch/mn10300/lib/do_csum.S new file mode 100644 index 000000000000..e138994e1667 --- /dev/null +++ b/arch/mn10300/lib/do_csum.S | |||
| @@ -0,0 +1,162 @@ | |||
| 1 | /* Optimised simple memory checksum | ||
| 2 | * | ||
| 3 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | ||
| 4 | * Written by David Howells (dhowells@redhat.com) | ||
| 5 | * | ||
| 6 | * This program is free software; you can redistribute it and/or | ||
| 7 | * modify it under the terms of the GNU General Public Licence | ||
| 8 | * as published by the Free Software Foundation; either version | ||
| 9 | * 2 of the Licence, or (at your option) any later version. | ||
| 10 | */ | ||
| 11 | #include <asm/cache.h> | ||
| 12 | |||
| 13 | .section .text | ||
| 14 | .balign L1_CACHE_BYTES | ||
| 15 | |||
| 16 | ############################################################################### | ||
| 17 | # | ||
| 18 | # unsigned int do_csum(const unsigned char *buff, size_t len) | ||
| 19 | # | ||
| 20 | ############################################################################### | ||
| 21 | .globl do_csum | ||
| 22 | .type do_csum,@function | ||
| 23 | do_csum: | ||
| 24 | movm [d2,d3],(sp) | ||
| 25 | mov d0,(12,sp) | ||
| 26 | mov d1,(16,sp) | ||
| 27 | mov d1,d2 # count | ||
| 28 | mov d0,a0 # buff | ||
| 29 | clr d1 # accumulator | ||
| 30 | |||
| 31 | cmp +0,d2 | ||
| 32 | beq do_csum_done # return if zero-length buffer | ||
| 33 | |||
| 34 | # 4-byte align the buffer pointer | ||
| 35 | btst +3,a0 | ||
| 36 | beq do_csum_now_4b_aligned | ||
| 37 | |||
| 38 | btst +1,a0 | ||
| 39 | beq do_csum_addr_not_odd | ||
| 40 | movbu (a0),d0 | ||
| 41 | inc a0 | ||
| 42 | asl +8,d0 | ||
| 43 | add d0,d1 | ||
| 44 | addc +0,d1 | ||
| 45 | add -1,d2 | ||
| 46 | do_csum_addr_not_odd: | ||
| 47 | |||
| 48 | cmp +2,d2 | ||
| 49 | bcs do_csum_fewer_than_4 | ||
| 50 | btst +2,a0 | ||
| 51 | beq do_csum_now_4b_aligned | ||
| 52 | movhu (a0+),d0 | ||
| 53 | add d0,d1 | ||
| 54 | addc +0,d1 | ||
| 55 | add -2,d2 | ||
| 56 | cmp +4,d2 | ||
| 57 | bcs do_csum_fewer_than_4 | ||
| 58 | |||
| 59 | do_csum_now_4b_aligned: | ||
| 60 | # we want to checksum as much as we can in chunks of 32 bytes | ||
| 61 | cmp +31,d2 | ||
| 62 | bls do_csum_remainder # 4-byte aligned remainder | ||
| 63 | |||
| 64 | add -32,d2 | ||
| 65 | mov +32,d3 | ||
| 66 | |||
| 67 | do_csum_loop: | ||
| 68 | mov (a0+),d0 | ||
| 69 | add d0,d1 | ||
| 70 | mov (a0+),e0 | ||
| 71 | addc e0,d1 | ||
| 72 | mov (a0+),e1 | ||
| 73 | addc e1,d1 | ||
| 74 | mov (a0+),e3 | ||
| 75 | addc e3,d1 | ||
| 76 | mov (a0+),d0 | ||
| 77 | addc d0,d1 | ||
| 78 | mov (a0+),e0 | ||
| 79 | addc e0,d1 | ||
| 80 | mov (a0+),e1 | ||
| 81 | addc e1,d1 | ||
| 82 | mov (a0+),e3 | ||
| 83 | addc e3,d1 | ||
| 84 | addc +0,d1 | ||
| 85 | |||
| 86 | sub d3,d2 | ||
| 87 | bcc do_csum_loop | ||
| 88 | |||
| 89 | add d3,d2 | ||
| 90 | beq do_csum_done | ||
| 91 | |||
| 92 | do_csum_remainder: | ||
| 93 | # cut 16-31 bytes down to 0-15 | ||
| 94 | cmp +16,d2 | ||
| 95 | bcs do_csum_fewer_than_16 | ||
| 96 | mov (a0+),d0 | ||
| 97 | add d0,d1 | ||
| 98 | mov (a0+),e0 | ||
| 99 | addc e0,d1 | ||
| 100 | mov (a0+),e1 | ||
| 101 | addc e1,d1 | ||
| 102 | mov (a0+),e3 | ||
| 103 | addc e3,d1 | ||
| 104 | addc +0,d1 | ||
| 105 | add -16,d2 | ||
| 106 | beq do_csum_done | ||
| 107 | |||
| 108 | do_csum_fewer_than_16: | ||
| 109 | # copy the remaining whole words | ||
| 110 | cmp +4,d2 | ||
| 111 | bcs do_csum_fewer_than_4 | ||
| 112 | cmp +8,d2 | ||
| 113 | bcs do_csum_one_word | ||
| 114 | cmp +12,d2 | ||
| 115 | bcs do_csum_two_words | ||
| 116 | mov (a0+),d0 | ||
| 117 | add d0,d1 | ||
| 118 | addc +0,d1 | ||
| 119 | do_csum_two_words: | ||
| 120 | mov (a0+),d0 | ||
| 121 | add d0,d1 | ||
| 122 | addc +0,d1 | ||
| 123 | do_csum_one_word: | ||
| 124 | mov (a0+),d0 | ||
| 125 | add d0,d1 | ||
| 126 | addc +0,d1 | ||
| 127 | |||
| 128 | do_csum_fewer_than_4: | ||
| 129 | and +3,d2 | ||
| 130 | beq do_csum_done | ||
| 131 | xor_cmp d0,d0,+2,d2 | ||
| 132 | bcs do_csum_fewer_than_2 | ||
| 133 | movhu (a0+),d0 | ||
| 134 | do_csum_fewer_than_2: | ||
| 135 | and +1,d2 | ||
| 136 | beq do_csum_add_last_bit | ||
| 137 | movbu (a0),d3 | ||
| 138 | add d3,d0 | ||
| 139 | do_csum_add_last_bit: | ||
| 140 | add d0,d1 | ||
| 141 | addc +0,d1 | ||
| 142 | |||
| 143 | do_csum_done: | ||
| 144 | # compress the checksum down to 16 bits | ||
| 145 | mov +0xffff0000,d2 | ||
| 146 | and d1,d2 | ||
| 147 | asl +16,d1 | ||
| 148 | add d2,d1,d0 | ||
| 149 | addc +0xffff,d0 | ||
| 150 | lsr +16,d0 | ||
| 151 | |||
| 152 | # flip the halves of the word result if the buffer was oddly aligned | ||
| 153 | mov (12,sp),d1 | ||
| 154 | and +1,d1 | ||
| 155 | beq do_csum_not_oddly_aligned | ||
| 156 | swaph d0,d0 # exchange bits 15:8 with 7:0 | ||
| 157 | |||
| 158 | do_csum_not_oddly_aligned: | ||
| 159 | ret [d2,d3],8 | ||
| 160 | |||
| 161 | do_csum_end: | ||
| 162 | .size do_csum, do_csum_end-do_csum | ||