[Info-vax] LLVM, volatile and async VMS I/O and system calls

[Dave Froble]

On 9/24/2021 6:16 PM, chris wrote:
> On 09/22/21 20:58, Bob Gezelter wrote:
>> On Wednesday, September 22, 2021 at 2:11:40 PM UTC-4, Simon Clubley
>> wrote:
> orld.
>>>
>>> There's a reason why volatile is used so liberally in embedded
>>> bare-metal
>>> programming. :-)
>>>
>>> Simon.
>
> Primarily because embedded spends a lot of time accessing hardware
> registers directly, for example:
>
> volatile unsigned char *ttyport = (volatile unsigned char*) TTY_PORT
>
> which assigns a numerc value to the pointer and tells the compiler
> not to optimise it away, nor change the value.
>
> Something application level code should rarely, if ever, see...

Well, now,  that sort of depends on your definition of "application 
level code", doesn't it?

I sometimes design/write stuff where I consider such issues.

Of course I write it in Basic, not that shitty C stuff.  Basic seems to 
usually get things right.  (Don't tell John I wrote that, he'll hold it 
against me when I ask him to fix Basic.)

:-)


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