41 lines
1.3 KiB
ArmAsm
41 lines
1.3 KiB
ArmAsm
// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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#include "../assembly.h"
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#ifdef __i386__
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// _chkstk (_alloca) routine - probe stack between %esp and (%esp-%eax) in 4k increments,
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// then decrement %esp by %eax. Preserves all registers except %esp and flags.
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// This routine is windows specific
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// http://msdn.microsoft.com/en-us/library/ms648426.aspx
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.text
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.balign 4
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DEFINE_COMPILERRT_FUNCTION(_alloca) // _chkstk and _alloca are the same function
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DEFINE_COMPILERRT_FUNCTION(__chkstk)
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push %ecx
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cmp $0x1000,%eax
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lea 8(%esp),%ecx // esp before calling this routine -> ecx
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jb 1f
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2:
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sub $0x1000,%ecx
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test %ecx,(%ecx)
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sub $0x1000,%eax
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cmp $0x1000,%eax
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ja 2b
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1:
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sub %eax,%ecx
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test %ecx,(%ecx)
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lea 4(%esp),%eax // load pointer to the return address into eax
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mov %ecx,%esp // install the new top of stack pointer into esp
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mov -4(%eax),%ecx // restore ecx
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push (%eax) // push return address onto the stack
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sub %esp,%eax // restore the original value in eax
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ret
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END_COMPILERRT_FUNCTION(__chkstk)
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END_COMPILERRT_FUNCTION(_alloca)
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#endif // __i386__
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