Copyright 2004 by M. Uli Kusterer Fri, 29 Nov -1901 11:06:32 GMT Comments on article blog-stack-backwards-head-hurts at Zathras.de http://www.zathras.de/angelweb/blog-stack-backwards-head-hurts.htm witness_dot_of_dot_teachtext_at_gmx_dot_net (M. Uli Kusterer) witness_dot_of_dot_teachtext_at_gmx_dot_net (M. Uli Kusterer) en-us http://www.zathras.de/angelweb/blog-stack-backwards-head-hurts.htm#comment2 http://www.zathras.de/angelweb/blog-stack-backwards-head-hurts.htm#comment2 Uli Kusterer writes:
@Jeff: Yeah. I was quite happy to find out that, since on OS X the *caller* cleans up the stack, you could easily add new parameters to a function which older versions would quietly ignore.

And 9-bit bytes: I'd heard that stuff like that existed, but so far I've never used a computer that had such an odd (from today's viewpoint) set-up. At least, not knowingly ;-)
http://www.zathras.de/angelweb/blog-stack-backwards-head-hurts.htm#comment1 http://www.zathras.de/angelweb/blog-stack-backwards-head-hurts.htm#comment1 Interestingly (at least from a historic perspective), the stack growing backwards is the reason that the order C evaluates arguments to a function is undefined. See http://cm.bell-labs.com/cm/cs/who/dmr/clcs.html specifically the section titled "Effects on the Language" for words from the language designer himself.

Consider varargs functions, those with an indeterminate number of arguments. Consider printf() - it can be quite sure that its first argument is at SP-4 irrespective of how many args were passed.

Many years back, I worked on a PRIME minicomputer which did not have a contiguous stack - instead, each function was responsible for allocating a block of "scratch memory" which it had to pass in to any function it called - this made it perfect for doing "stack crawlbacks" but a nightmare for compiler writers since the compiler had to determine (and record) the amount of temporary stack space a function would need, and to CALL a function, you needed to look at its declared requirement. Little surprise that the natural language on a PRIME was Fortran - to implement C, they actually had to code knowledge of printf()s behaviour into the compiler.

Still, that was better than GCOS with its 9 bit bytes. :-)