assembly in future C standard HCF Gerry Wheeler

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  • 1. which is the better way to declare dynamic single dimension array inside struct
    Recently i saw a code in which there was a structer defination similar as bellow: struct foo { int dummy1; int dummy2; int last[1] }; In application the above array is always allocated at runtime using malloc.In this last member of the structer "int last[1]" is not actually used as array with single element but when alloacting space for struct foo extra memory is allocated and last is used as array with more then one element. my question is what are the advantages of using the above defination instead of the shown below. struct foo { int dummy1; int dummy2; int *last; }; The only advantage i can think of is that we will have to call single malloc in first declaration and two malloc in second declaration and also that in first declaration all the memeory allocated will be contigous which may lead to less framgmentation and better cache utilization. My question is does using first defination for accessing of elements faster when compared to second. If yes why? Thanks in advance.
  • 2. grabbing file size
    i'm working on two client and server programs that send and recieve files using sockets. i saw a c++ example using csockets, and thought i could use the basic idea of what the code was doing to form my own c program. i have an idea of how to send binary files via sockets, but the problem is that to use send() i need to know the size (in bytes) of the file i want to send. any ideas on how to accomplish this? -- Jesse Engle
  • 3. finding the name of the function
    Hi, I've written a piece of network code in C. I'm pritting lots of debugging information, just in case the program is screwed :) Is there any built-in function that gives the name of the function from which it is called? For example, int foo() { print_function_name(); /* some built-in system call */ } should output the name as "foo()" or somewhat similarly. I've been coding in C for almost 2 and half years but never used such a function till now. Any help is appreciated. regards, GVK -- Happy Hacking!!!

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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