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1 / This Source Code Form is subject to the terms of the Mozilla Public |
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2 / License, v. 2.0. If a copy of the MPL was not distributed with this |
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3 / file, You can obtain one at http://mozilla.org/MPL/2.0/. |
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4 |
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5 / ** ARCFOUR implementation optimized for AMD64. |
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6 / ** |
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7 / ** The throughput achieved by this code is about 320 MBytes/sec, on |
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8 / ** a 1.8 GHz AMD Opteron (rev C0) processor. |
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9 |
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10 .text |
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11 .align 16 |
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12 .globl ARCFOUR |
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13 .type ARCFOUR,@function |
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14 ARCFOUR: |
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15 pushq %rbp |
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16 pushq %rbx |
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17 movq %rdi, %rbp / key = ARG(key) |
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18 movq %rsi, %rbx / rbx = ARG(len) |
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19 movq %rdx, %rsi / in = ARG(in) |
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20 movq %rcx, %rdi / out = ARG(out) |
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21 movq (%rbp), %rcx / x = key->x |
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22 movq 8(%rbp), %rdx / y = key->y |
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23 addq $16, %rbp / d = key->data |
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24 incq %rcx / x++ |
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25 andq $255, %rcx / x &= 0xff |
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26 leaq -8(%rbx,%rsi), %rbx / rbx = in+len-8 |
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27 movq %rbx, %r9 / tmp = in+len-8 |
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28 movq 0(%rbp,%rcx,8), %rax / tx = d[x] |
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29 cmpq %rsi, %rbx / cmp in with in+len-8 |
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30 jl .Lend / jump if (in+len-8 < in) |
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31 |
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32 .Lstart: |
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33 addq $8, %rsi / increment in |
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34 addq $8, %rdi / increment out |
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35 |
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36 / generate the next 8 bytes of the rc4 stream into %r8 |
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37 movq $8, %r11 / byte counter |
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38 1: addb %al, %dl / y += tx |
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39 movl 0(%rbp,%rdx,8), %ebx / ty = d[y] |
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40 movl %ebx, 0(%rbp,%rcx,8) / d[x] = ty |
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41 addb %al, %bl / val = ty + tx |
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42 movl %eax, 0(%rbp,%rdx,8) / d[y] = tx |
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43 incb %cl / x++ (NEXT ROUND) |
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44 movl 0(%rbp,%rcx,8), %eax / tx = d[x] (NEXT ROUND) |
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45 movb 0(%rbp,%rbx,8), %r8b / val = d[val] |
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46 decb %r11b |
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47 rorq $8, %r8 / (ror does not change ZF) |
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48 jnz 1b |
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49 |
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50 / xor 8 bytes |
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51 xorq -8(%rsi), %r8 |
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52 cmpq %r9, %rsi / cmp in+len-8 with in |
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53 movq %r8, -8(%rdi) |
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54 jle .Lstart / jump if (in <= in+len-8) |
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55 |
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56 .Lend: |
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57 addq $8, %r9 / tmp = in+len |
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58 |
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59 / handle the last bytes, one by one |
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60 1: cmpq %rsi, %r9 / cmp in with in+len |
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61 jle .Lfinished / jump if (in+len <= in) |
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62 addb %al, %dl / y += tx |
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63 movl 0(%rbp,%rdx,8), %ebx / ty = d[y] |
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64 movl %ebx, 0(%rbp,%rcx,8) / d[x] = ty |
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65 addb %al, %bl / val = ty + tx |
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66 movl %eax, 0(%rbp,%rdx,8) / d[y] = tx |
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67 incb %cl / x++ (NEXT ROUND) |
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68 movl 0(%rbp,%rcx,8), %eax / tx = d[x] (NEXT ROUND) |
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69 movb 0(%rbp,%rbx,8), %r8b / val = d[val] |
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70 xorb (%rsi), %r8b / xor 1 byte |
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71 movb %r8b, (%rdi) |
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72 incq %rsi / in++ |
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73 incq %rdi / out++ |
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74 jmp 1b |
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75 |
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76 .Lfinished: |
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77 decq %rcx / x-- |
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78 movb %dl, -8(%rbp) / key->y = y |
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79 movb %cl, -16(%rbp) / key->x = x |
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80 popq %rbx |
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81 popq %rbp |
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82 ret |
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83 .L_ARCFOUR_end: |
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84 .size ARCFOUR,.L_ARCFOUR_end-ARCFOUR |