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Richard Erlacher
10/27/11 15:35
Read: 438 times
Denver, Co

#184403 - You missed my point again
Responding to: Per Westermark's previous message
Per Westermark said:
Richard Erlacher said:
That's only true if the evaluation compiler puts the code where it can actually run on the target. That is, after all, the issue that initiated this discussion.

Doesn't matter if I have to use a processor with more code space when evaluating the compiler.

The goal of evaluation is to find out if the compiler is good. It will be good whatever 8051 chip you use, since they all use the same instruction set.

I don' agree. If you want to evaluate the timing of a particular module, one small enough to run in the 2kB space, you need to run it on the target, else you need tools to evaluate the timing automatically under simulation, and those tools are even scarcer than "good" compilers. The easy, quick, simple and deterministic way to do this is to run the code on the target MCU. Further, you have to be able to load other modules with which the one of interest has to interact, else your evaluation will be little more than an arbitrary value judgment.

An evaluation version that allows the code to be placed at any location would mean that a user only making use of chips with 4kB of code space never needs to buy any commercial version of the compiler, so it really is important for the compiler vendor to give them an incentive to switch from the evaluation version to a bought version.

Richard said:
Nobody's discussing "ARM-class" processors at this point. I know ARM would like to supplant the 805x's but there are places where they'll NEVER fit.

But you missed the important note here, that I gave in the next paragraph (quoted below): lots of embedded code is more or less one-to-one between source lines and peripherial accesses. So not much need for any optimization. We do not want the compiler to remove writes to our UART transmit registers or reads from GPIO pins. And the compiler may not change the order.

Richard said:
But even more importantly - the critical part of code is likely to contain lots if GPIO accesses, where there is a one-to-one between source lines and hardware accesses. Exactly how can a compiler fail when there isn't anything to optimize?

I'm not sure optimization is the issue. Compilers from different vendors produce code that runs at different rates, uses differing volumes of code space, uses more or fewer resources ...

But that can be evaluated within 4kB of code space for an 8051 compiler.

Just how would YOU do it without running it on the target MCU? Would it be anything more than your expert opinion?

Richard said:
After being repeatedly lied-to by the KEIL people, not to suggest they're the only ones, and probably as much out of ignorance as out of evil intent, I've nearly given up on trying to deal with software vendors.

Strong claim from you. Care to back up that with some examples of how Keil staff have lied to you?

I'll give you one that stands out ... When I asked about precisely simulating the address-mode switching in the DS89C420, about a decade ago, the tech-droid with whom I was speaking told me that it had been proven to be impossible. The guy said that it was impossible to tell when the timing effects took place, hence, it couldn't be simulated.

I know better, as the device is entirely deterministic in its operation, and started designing my own simulator, which effort was later abandoned because it's easier to hook the circuit up to the logic analyzer and observe the timing there. Of course, the code was, by that time, already written in ASM.

I've mentioned this particular matter before. I know a bit about simulators, having managed to get through grad school by doing little other than writing or modifying simulators. I doubt simulation has changed much since then. It's like math. It's the same process and language. What worked then works now ... maybe even better, but it still works.


List of 53 messages in thread
Linking C programs with Keil evaluation      David Prentice      09/06/11 11:02      
   Eval Tools.      Michael Karas      09/06/11 11:15      
      That makes sense      David Prentice      09/06/11 12:11      
         It's not that much more useable      Richard Erlacher      10/25/11 18:44      
            Work-around for evaluation version limitations?      Per Westermark      10/25/11 23:50      
            Marked -1      Michael Karas      10/26/11 06:26      
               I'm not so sure you're right here ...      Richard Erlacher      10/26/11 07:55      
                  Irrelevant if people have ideas - should they be debated?      Per Westermark      10/26/11 08:19      
                     There's a reason I haven't done it ...      Richard Erlacher      10/26/11 10:36      
                        Would not represent a valid evaluation      Per Westermark      10/27/11 02:00      
                           Wait a minute ... You've got this wrong ...      Richard Erlacher      10/27/11 09:57      
                     One question      Richard Erlacher      10/26/11 12:43      
                        What about the guy who simply wants to evaluate the product?      Andy Neil      10/26/11 14:05      
                           sometimes coding situations and requirements differ      Richard Erlacher      10/26/11 18:57      
                        How would you like it?      Andy Neil      10/26/11 14:13      
                           That's not what I'm asking them to do      Richard Erlacher      10/26/11 19:17      
                              A message from the OP.      David Prentice      10/27/11 03:55      
                                 I don't supply the compiler ...      Richard Erlacher      10/27/11 10:08      
                        Wrong view on evaluation tools      Per Westermark      10/27/11 03:32      
                           as I've said before, where you sit determines what you see      Richard Erlacher      10/27/11 10:47      
                              Still failing to recognize reason for hole in code map      Per Westermark      10/27/11 12:33      
                                 You missed my point again      Richard Erlacher      10/27/11 15:35      
                                    Simulate or use Logic Analyser      David Prentice      10/28/11 05:41      
                                       ramblings      Erik Malund      10/28/11 07:51      
                                       Using evaluation software and hardware      Richard Erlacher      10/28/11 09:44      
                                          The above would be true if....      Erik Malund      10/28/11 10:24      
                                             You don't seriously believe that, do you?      Richard Erlacher      10/28/11 18:54      
                                                A thief is a thief        Per Westermark      10/29/11 07:01      
                                                   Indeed...        Michael Karas      10/29/11 09:47      
                                                   FIrst of all, I don't advocate theivery      Richard Erlacher      10/29/11 14:46      
                                                      and more mumbo jumbo in the reply      Erik Malund      10/29/11 15:47      
                                                      Can _you_ not read debugger output?      Per Westermark      10/29/11 17:39      
                                          8255      Andy Peters      10/28/11 13:26      
                                             Yes, but they're still shipped on some 805x trainer boards      Richard Erlacher      10/28/11 18:42      
                                             Just sayin'      Michael Karas      10/29/11 05:50      
                  Square Wheels for the Car      Michael Karas      10/26/11 10:06      
                     I disagree ... not that that should surprise anyone      Richard Erlacher      10/26/11 10:54      
                        eval and evaluation      Erik Malund      10/26/11 11:25      
                           Yes, if only they were useful ...      Richard Erlacher      10/26/11 12:31      
      Also "LPC900 Studio"      Andy Neil      09/06/11 12:32      
         They all seem crippled      David Prentice      09/06/11 14:22      
            comments      Erik Malund      09/06/11 16:17      
            They all seem crippled      Andy Neil      09/06/11 16:22      
               Yes ... SDCC ... the obvious solution      Richard Erlacher      09/08/11 08:30      
                  what's obvious about it      Erik Malund      09/08/11 09:00      
                     Why not?      Andy Neil      09/08/11 10:48      
                        reasons      Erik Malund      09/08/11 10:59      
                           Unfortunately      Andy Neil      09/08/11 14:13      
                              re Keil      Erik Malund      09/09/11 07:13      
                                 15 years ago?      Maarten Brock      09/09/11 09:28      
                                    OK, maybe not      Erik Malund      09/09/11 09:48      
            reasonable price      Erik Malund      09/07/11 03:41      
            raisonance is 4k with no code offset      Marshall Brown      10/25/11 13:59      

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