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Last change
on this file since 444 was
444,
checked in by satin@…, 6 years ago
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add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc
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File size:
1.5 KB
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| 1 | /* |
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| 2 | * ==================================================== |
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| 3 | * Copyright (C) 1998, 2002, 2008 by Red Hat Inc. All rights reserved. |
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| 4 | * |
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| 5 | * Permission to use, copy, modify, and distribute this |
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| 6 | * software is freely granted, provided that this notice |
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| 7 | * is preserved. |
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| 8 | * ==================================================== |
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| 9 | */ |
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| 10 | |
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| 11 | #include "i386mach.h" |
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| 12 | |
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| 13 | .global SYM (strlen) |
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| 14 | SOTYPE_FUNCTION(strlen) |
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| 15 | |
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| 16 | SYM (strlen): |
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| 17 | |
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| 18 | pushl ebp |
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| 19 | movl esp,ebp |
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| 20 | pushl edi |
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| 21 | #ifdef __iamcu__ |
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| 22 | movl eax,edx |
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| 23 | #else |
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| 24 | movl 8(ebp),edx |
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| 25 | #endif |
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| 26 | |
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| 27 | #if defined __OPTIMIZE_SIZE__ || defined __iamcu__ |
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| 28 | cld |
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| 29 | movl edx,edi |
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| 30 | movl $4294967295,ecx |
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| 31 | xor eax,eax |
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| 32 | repnz |
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| 33 | scasb |
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| 34 | #else |
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| 35 | /* Modern x86 hardware is much faster at double-word |
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| 36 | manipulation than with bytewise repnz scasb. */ |
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| 37 | |
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| 38 | /* Do byte-wise checks until string is aligned. */ |
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| 39 | movl edx,edi |
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| 40 | test $3,edi |
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| 41 | je L5 |
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| 42 | movb (edi),cl |
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| 43 | incl edi |
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| 44 | testb cl,cl |
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| 45 | je L15 |
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| 46 | |
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| 47 | test $3,edi |
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| 48 | je L5 |
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| 49 | movb (edi),cl |
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| 50 | incl edi |
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| 51 | testb cl,cl |
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| 52 | je L15 |
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| 53 | |
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| 54 | test $3,edi |
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| 55 | je L5 |
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| 56 | movb (edi),cl |
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| 57 | incl edi |
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| 58 | testb cl,cl |
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| 59 | je L15 |
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| 60 | |
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| 61 | L5: |
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| 62 | subl $4,edi |
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| 63 | |
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| 64 | /* loop performing 4 byte mask checking for desired 0 byte */ |
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| 65 | .p2align 4,,7 |
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| 66 | L10: |
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| 67 | addl $4,edi |
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| 68 | movl (edi),ecx |
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| 69 | leal -16843009(ecx),eax |
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| 70 | notl ecx |
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| 71 | andl ecx,eax |
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| 72 | testl $-2139062144,eax |
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| 73 | je L10 |
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| 74 | |
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| 75 | /* Find which of four bytes is 0. */ |
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| 76 | notl ecx |
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| 77 | incl edi |
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| 78 | |
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| 79 | testb cl,cl |
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| 80 | je L15 |
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| 81 | incl edi |
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| 82 | shrl $8,ecx |
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| 83 | |
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| 84 | testb cl,cl |
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| 85 | je L15 |
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| 86 | incl edi |
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| 87 | shrl $8,ecx |
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| 88 | |
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| 89 | testb cl,cl |
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| 90 | je L15 |
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| 91 | incl edi |
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| 92 | |
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| 93 | #endif |
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| 94 | |
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| 95 | L15: |
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| 96 | subl edx,edi |
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| 97 | leal -1(edi),eax |
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| 98 | |
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| 99 | leal -4(ebp),esp |
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| 100 | popl edi |
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| 101 | leave |
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| 102 | ret |
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