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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 1905 | serge | 1 | |
| 2 | .global __alloca |
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| 3 | |||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 | __alloca: |
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| 8 | pushl %ecx /* save temp */ |
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| 9 | leal 8(%esp), %ecx /* point past return addr */ |
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| 10 | cmpl $0x1000, %eax /* > 4k ?*/ |
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| 11 | jb Ldone |
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| 12 | |||
| 13 | |||
| 14 | subl $0x1000, %ecx /* yes, move pointer down 4k*/ |
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| 15 | orl $0x0, (%ecx) /* probe there */ |
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| 16 | subl $0x1000, %eax /* decrement count */ |
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| 17 | cmpl $0x1000, %eax |
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| 18 | ja Lprobe /* and do it again */ |
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| 19 | |||
| 20 | |||
| 21 | subl %eax, %ecx |
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| 22 | orl $0x0, (%ecx) /* less than 4k, just peek here */ |
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| 23 | |||
| 24 | |||
| 25 | movl %ecx, %esp /* decrement stack */ |
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| 26 | movl (%eax), %ecx /* recover saved temp */ |
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| 27 | movl 4(%eax), %eax /* recover return address */ |
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| 28 | |||
| 29 | |||
| 30 | jumping to %eax preserves the cached call-return stack |
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| 31 | used by most modern processors. */ |
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| 32 | pushl %eax |
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| 33 | ret |
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| 34 |