Re: "undefined behavior"?

Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:

On 14/06/2024 00:55, Ben Bacarisse wrote:

Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
 

On 13/06/2024 19:01, bart wrote:

 

And here it just gets even uglier. You also get situations like this:
      uint64_t i=0;
      printf("%lld\n", i);
This compiles OK with gcc -Wall, on Windows64. But compile under Linux64
and it complains the format should be %ld. Change it to %ld, and it
complains under Windows.
It can't tell you that you should be using one of those ludicrous macros.
I've also just noticed that 'i' is unsigned but the format calls for
signed. That may or may not be deliberate, but the compiler didn't say
anything.
>

Exactly. We can't have this just to print out an integer.

This is how C works.  There's no point in moaning about it.  Use another
language or do what you have to in C.
 

In Baby X I provide a function called bbx_malloc(). It's is guaranteed
never to return null. Currently it just calls exit() on allocation failure.
But it also limits allocation to slightly under INT_MAX. Which should be
plenty for a Baby program, and if you want more, you always have big boy's
malloc.

And if you need to change the size?
 

But at a stroke, that gets rid of any need for size_t,

But sizeof, strlen (and friends like the mbs... and wcs... functions),
strspn (and friend), strftime, fread, fwrite. etc. etc. all return
size_t.
 

But these are not Baby X functions.

Neither is malloc but you wanted t replace that to get rid of the need
for size_t.

I confess that I am all at sea about what you are doing.  In essence, I
don't understand the rules of the game so I should probably just stop
commenting.

and long is very
special purpose (it holds the 32 bit rgba values).

Isn't that rather wasteful when long is 64 bits?
 

No, because we store images as unsigned char buffers. But it's convenient
to pass around coulor values in a single variable.

Right.  So you don't always use long for "holding rgba values".  Another
rule I didn't know.

However there is the worry that accessing rgba channels as bytes rather
than insisting that the buffer be aligned, and accessing as a 32-bit
value,

Which is why I thought you might be including images in the notion of
"holding rgba values".

--
Ben.