| 1 | /* ----------------------------------------------------------------------- * |
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| 2 | * |
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| 3 | * Copyright 2008 H. Peter Anvin - All Rights Reserved |
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| 4 | * |
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| 5 | * Permission is hereby granted, free of charge, to any person |
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| 6 | * obtaining a copy of this software and associated documentation |
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| 7 | * files (the "Software"), to deal in the Software without |
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| 8 | * restriction, including without limitation the rights to use, |
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| 9 | * copy, modify, merge, publish, distribute, sublicense, and/or |
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| 10 | * sell copies of the Software, and to permit persons to whom |
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| 11 | * the Software is furnished to do so, subject to the following |
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| 12 | * conditions: |
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| 13 | * |
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| 14 | * The above copyright notice and this permission notice shall |
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| 15 | * be included in all copies or substantial portions of the Software. |
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| 16 | * |
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| 17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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| 18 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES |
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| 19 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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| 20 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT |
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| 21 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, |
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| 22 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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| 23 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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| 24 | * OTHER DEALINGS IN THE SOFTWARE. |
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| 25 | * |
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| 26 | * ----------------------------------------------------------------------- */ |
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| 27 | |
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| 28 | /* |
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| 29 | * memset.S |
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| 30 | * |
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| 31 | * Reasonably efficient memset, using aligned transfers at least |
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| 32 | * for the destination operand. |
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| 33 | */ |
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| 34 | |
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| 35 | .globl memset |
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| 36 | .type memset,@function |
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| 37 | .text |
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| 38 | memset: |
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| 39 | movl 0xc(%esp),%ecx |
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| 40 | movl 0x8(%esp),%edx |
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| 41 | movl 0x4(%esp),%eax |
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| 42 | |
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| 43 | jecxz 6f |
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| 44 | |
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| 45 | pushl %edi |
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| 46 | pushl %ebx |
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| 47 | pushl %eax /* Return value */ |
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| 48 | |
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| 49 | movl %eax,%edi |
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| 50 | movb %dl,%dh |
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| 51 | movzwl %dx,%eax |
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| 52 | shll $16,%edx |
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| 53 | orl %edx,%eax |
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| 54 | |
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| 55 | /* Initial alignment */ |
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| 56 | movl %edi,%edx |
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| 57 | shrl $1,%edx |
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| 58 | jnc 1f |
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| 59 | stosb |
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| 60 | decl %ecx |
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| 61 | 1: |
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| 62 | movb %cl,%bl |
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| 63 | cmpl $2,%ecx |
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| 64 | jb 3f |
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| 65 | shrl $1,%edx |
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| 66 | jnc 2f |
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| 67 | stosw |
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| 68 | subl $2,%ecx |
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| 69 | 2: |
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| 70 | /* Bulk transfer */ |
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| 71 | movb %cl,%bl |
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| 72 | shrl $2,%ecx |
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| 73 | rep; stosl |
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| 74 | |
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| 75 | testb $2,%bl |
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| 76 | jz 4f |
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| 77 | stosw |
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| 78 | 3: |
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| 79 | 4: |
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| 80 | testb $1,%bl |
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| 81 | jz 5f |
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| 82 | stosb |
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| 83 | 5: |
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| 84 | popl %eax /* Return value */ |
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| 85 | popl %ebx |
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| 86 | popl %edi |
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| 87 | 6: |
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| 88 | ret |
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| 89 | |
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| 90 | .size memset, .-memset |
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