ARM bare-metal programming in D (cont) - volatile

[Mike]

On Thursday, 24 October 2013 at 06:25:20 UTC, Arjan wrote:
> On Thursday, 24 October 2013 at 00:43:11 UTC, Mike wrote:
>> Hello again,
>>
>> I'm interested in ARM bare-metal programming with D, and I'm 
>> trying to get my head wrapped around how to approach this.  
>> I'm making progress, but I found something that was surprising 
>> to me: deprecation of the volatile keyword.
>>
>> In the bare-metal/hardware/driver world, this keyword is 
>> important to ensure the optimizer doesn't cache reads to 
>> memory-mapped IO, as some hardware peripheral may modify the 
>> value without involving the processor.
>>
>> I've read a few discussions on the D forums about the volatile 
>> keyword debate, but noone seemed to reconcile the need for 
>> volatile in memory-mapped IO.  Was this an oversight?
>>
>> What's D's answer to this?  If one were to use D to read from 
>> memory-mapped IO, how would one ensure the compiler doesn't 
>> cache the value?
>
> This article might also give some insight in the problems with 
> volatile:
> http://blog.regehr.org/archives/28

Arjan, Thanks for the information.  I basically agree with 
premise of that blog, but the author also said "If you are 
writing code for an in-order embedded processor and have little 
or no infrastructure besides the C compiler, you may need to lean 
more heavily on volatile".  Well, that's me.

My goal is to target bare-metal embedded systems with D, so I'm 
looking for a volatile-like solution in D.  I don't care if the 
language has the "volatile" keyword or not, I just want to be 
able to read and write to my IO as fast as possible, and I'm 
wondering if D has a way to do this in a way that is comparable 
to what can be achieved in C.