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From: | deleveld AT my-deja DOT com |
Newsgroups: | comp.os.msdos.djgpp |
Subject: | question about stack frames |
Date: | Thu, 30 Dec 1999 15:07:50 GMT |
Organization: | Deja.com - Before you buy. |
Lines: | 52 |
Message-ID: | <84frs6$l3h$1@nnrp1.deja.com> |
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X-Article-Creation-Date: | Thu Dec 30 15:07:50 1999 GMT |
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To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
Reply-To: | djgpp AT delorie DOT com |
Hello Everyone, I have a question about DJGPP and stack frames. I am working on a recursive function that has to recursive quite a few times and I'd like to be able to calculate how many times the function can recurse without overflowing the stack. My function is like this: static void _draw_recursive(Window* const window, const ExposeEvent* const rect) { ExposeEvent *event; Window* ptr = window->higher; ... do some stuff with the arguments and local variables ... } Now I have already tried to reduce the amount and size of local variables. i.e. I need an Expose event and I malloc and free a pointer in the function instead of making it a local varaible. What confuses me is when I look at the assembler output for the function I see this: __draw_recursive: subl $44,%esp pushl %ebp pushl %edi pushl %esi pushl %ebx movl 64(%esp),%eax ... some other stuff ... It looks to me like there are $44 bytes reserved on the stack when I am pretty sure that I need a lot less that that. I calculate that I need at most 4 pointers i.e. 16 bytes. Can anyone explain this do me? Any advice on making the stack frame as small as possible? Thanks you, Doug Eleveld Sent via Deja.com http://www.deja.com/ Before you buy.
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