assembly in future C standard HCF Gerry Wheeler

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    Ok, I'm reading "The C Programming Language: 2nd Edition" and I'm on chapter 1.5.1 and here's the program you're sposed to make: #include <stdio.h> /* copy input to output; 1st version */ main() { int c; c = getchar(); while (c != EOF) { putchar(c); c = getchar(); } } Ok, now here's what I'm confused about: I read it all and everything and I'm not sure what it's sposed to do. I tried it and say if I type: a Then it'll mimic it, so if I type "a" and press enter it'll do this: a a Is that what it's supposed to do? And if so then why doesn't it make a difference if I take out the "!"(not equal to(I think)). Any help is greatly appreciated, thanks!
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  • 3. printf statement not executed
    Why is "TEST" not printed when I run this code after comiling? #include <stdio.h> int main() { int a,b,c,d,e,x; int *variables[5]; a = 1; b = a*2; c = b*2; d = c*2; e = d*2; variables[0] = &a; variables[1] = &b; variables[2] = &c; variables[3] = &d; variables[4] = &e; for(x=0; x<5; x++) printf("Variable %c = %d\n", 'a'+ x, *variables[x]); printf("TEST"); return(0); }

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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