assembly in future C standard HCF Gerry Wheeler

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  • 1. 'static' : strange behavior
    I'm working with a code (not mine) on embedded MIPS platform and ran across a weird behavior. I have a function: int nvram_init(void *si) { static int nvram_status = -1; ... } This function gets called only at one place of the firmware, what really strange is that output value of 'nvram_status' at the very beginning of the 'nvram_init()' is always 0. As per my knowledge, a variable declared 'static' withing a function's body must maintain it value between the function's calls, but it doesn't seem to be the case here! Should I be looking for some hardware/compiler specific trick, or I'm missing something more trivial? -- Mark
  • 2. 'static' : strange behavior
    On Dec 28, 2:24m, "Mark" < XXXX@XXXXX.COM > wrote: > I print the value of 'nvram_status', below is more complete snippet: Since you are reporting something that seems unusual, it would be good if you posted some _complete_ code that you have actually run on your system.
  • 3. Compare to a defined constants in C?
    I am trying to compare to a defined constants in C, and I have simplified my program to the following.. #include "stdio.h" #include "stdlib.h" #define INVALID_VALUE -999; int main(int argc, const char* argv[]) { int test=0; if(test==INVALID_VALUE) //The error line.. return INVALID_VALUE; return 0; }; And when I use gcc to compile. it gives out error "error: expected before token" Any reason that this cannot be done.
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Re: assembly in future C standard HCF Gerry Wheeler

Postby Walter Banks » Sat, 04 Nov 2006 22:35:39 GMT

As this thread wanders off topic this industry was introduced to a new
mnemonic in Byte article about decoding the undocumented
Motorola 6800 instructions. The HCF (Halt Catch Fire) opcode $DD
or $D9. HFC locked up the processor and cycled the address bus
The author of that article was Gerry Wheeler.

Gerry Wheeler, 54, died October 15, 2006, advanced non-Hodgkins
lymphoma cancer. Gerry made significant contributions to the technology
of the embedded systems world and was a key part of the development
of many household name products.

Programmer, Ham KG4NBB, author, father, husband, active commuity
participant Gerry will be missed by all.

w..


Similar Threads:

1.assembly in future C standard

Peter Nilsson < XXXX@XXXXX.COM > wrote:

(Crossposted to comp.std.c, with followups directed there, hopefully
 appropriately.  The original post discussed the possibility of whether
 __asm or something similar to it would be added to the C standard.)

> Contrary to Richard Heathfield's categorical statement, it is not an
> absolute given that there will never be an asm keyword in C. But it
> is unlikely because it's already clear that the asm keyword in C++ has
> not served to truly standardise the syntax of inline assembly.

One idea that was not mentioned in the original thread (I imagine for
good reason, because it's a half-baked and probably stupid idea that
occurred to me reading your post) would be to allow for some kind of
conditional assembly, just perhaps something like

#pragma assemble
#pragma X86 /* Inner pragma's implementation-defined */
  /* Inline assembly, which the implementation can ignore or not */
#pragma no-assemble
  /* Stock C code for implementations that can't or won't accept the
   * assemble pragma: */
  for( i=1; i < 10; i++ ) {
    foo();
    /* ... */
  }
#pragma end-assemble

The end result would be something like "If the implementation attempts
to inline the assembly code contained within a #pragma assemble
directive, the behavior is implementation-defined.  Otherwise the
assembly code shall be ignored and the C code contained within any
corresponding #pragma no-assemble directive shall be compiled as
though no directives were present."  It would require adding some
duties to the #pragma directive, but it would allow implementors to
take a reasonable shot at using targetted assembly instructions when
appropriate and available, and reverting to ordinary C otherwise.

I'm sure there are reasons why this is stupid and/or impossible, or it
would have been done already :-)

> At the end of the day, the committee could probably spend many man
> weeks deciding issues on an __asm keyword, but for what? Most
> implementations will keep their existing syntax, and most programmers
> who use inline assembly will no doubt continue to prefer the localised
> syntax because it's less cumbersome than any standard syntax.

Indeed, but it's an interesting thought experiment to consider how the
committee *might* add assembly to C if they chose to do so.  (Well,
interesting to me, at least.)

-- 
C. Benson Manica           | I *should* know what I'm talking about - if I
cbmanica(at)gmail.com      | don't, I need to know.  Flames welcome.



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