Hi Kiste, Some answers to the things you mention.
About volatile variables. This is what the JAL documentation says about is. "The VOLATILE keyword guarantees that a variable that is either used or assigned will not be optimized away, and the variable will be only read (or written) once when evaluating an expression.Normally, if a variable is assigned a value that is never used, the assignment is removed and the variable is not allocated any space. If the assignment is an expression, the expression *will* be fully evaluated. If a variable is used, but never assigned, all instances of the variable will be replaced with the constant 0 (of the appropriate type) and the variable will not be allocated any space." Volatile is especially needed if a perhiperal would update a variable since the compiler does not know that and so it would optimize it away since it does not 'see' that the variable is used by the program About documentation. The JAL documentation is in the 'compiler' directory that is present in the install or the bee-package. You are right that the documentation does not talk about mapping bytes onto words. I could add that as an example since it is something which is used quite often. Then my thoughts about the issue you mention. I see that you are updating a word value (not a byte value) and since the PIC is byte oriented a word consists of two bytes. Updating a word value requires several instructions and I can imagine that if an interrupt occurs exactly in between these instructions that things go wrong. What you would need is a semaphore but since we do not have that, a way around is that you before printing your word you disable that specific interrupt that is also updating that same word. If you do not want to delay the interrupt too much because of the print function you could also do the following: -) Disable the interrupt -) Copy the word value to a local word variable -) Enable the interrupt Kind regards, Rob ________________________________ Van: 'Oliver Seitz' via jallib <[email protected]> Verzonden: vrijdag 27 november 2020 12:28 Aan: [email protected] <[email protected]> Onderwerp: Re: [jallib] Compiler doesn't honour "volatile" Hi! Yes, thanks, memory is fine, the data logger is up and running, storing 2048 values at 24 bit resolution, great! :-) I have a program, but it uses a watch crystal and counts external pulses. And, for saving time... I've now seen the error three times within ten days. Thinking again about the issue, I'm not really sure if "volatile" is the right term to describe the problem. "volatile" specifies, that for every read/write in the source code, exactly one read/write in the machine code is done. Perhaps it is up to the program author to ensure the correct reading outside of the interrupt if a variable is modified inside the interrupt and vice versa. Then it would be a subject of documentation. Which, by the way, I didn't read :-D But, while disgressing already, a bit to make JAL popular and usable... Where is the official documentation? I lately had to place byte variables over dword variables and couldn't find the syntax in any document, only placing bits. I kind of tried luckily with var byte name1 at name2+byte_offset. (Ok, found the website and the language reference. But no byte offsets :-) ) Greets, Kiste Am Freitag, 27. November 2020, 11:39:06 MEZ hat Rob CJ <[email protected]> Folgendes geschrieben: Hi Kiste, Hmm, my next puzzle for the weekend. Can you send a complete sample program that I can use? It will save me time. BTW. Did you already test the new build compiler that solves the memory issue? Thanks. Kind regards, Rob ________________________________ Van: 'Oliver Seitz' via jallib <[email protected]> Verzonden: vrijdag 27 november 2020 07:44 Aan: Jallib <[email protected]> Onderwerp: [jallib] Compiler doesn't honour "volatile" Sorry... This isn't in fact the proper list for compiler issues, is it? This one is probably more severe. I'll start with the example. This is the data I've received: ?2807 2808 1 ?2807 2809 2 ?2807 2810 2 ?2807 2811 4 ?2807 2812 4 ?2807 2813 6 ?2807 2814 7 ?2807 2815 8 ?2807 2816 264 It's generated from this part of code, running on an PIC18F27K42. extra_time is increased in an interrupt every 16 seconds. It is declared as var volatile word, so the compiler should make sure that the bytes of the variable are in a consistent state: diff=word(extra_time-last_pulse_time_uw) if print_debug then print_debug=false serial="?" print_word_dec(serial,last_pulse_time_uw) serial=" " print_word_dec(serial,extra_time) serial=" " print_dword_dec(serial,diff) print_crlf(serial) end if Let me repeat some of the results above in hex: AFE-AF7 =7 AFF-AF7 =8 B00-AF7 =108 So, what has happened? The last line is clearly wrong. The subtraction was done just as extra_time was in the process of increasing. The low byte was processed before, the high byte was processed after the interrupt fired. So the actual subtraction done was BFF-AF7, with the result of 108. I've had a look at the asm file. Both bytes of the variable are just handled one after the other, both in the main program and in the interrupt service routine. The "volatile" declaration does not seem to do anything. Greets, Kiste -- You received this message because you are subscribed to the Google Groups "jallib" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/1713803051.2007385.1606459457507%40mail.yahoo.com<https://groups.google.com/d/msgid/jallib/1713803051.2007385.1606459457507%40mail.yahoo.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "jallib" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/AM0PR07MB6241378E01DF90BC2AFE3E46E6F80%40AM0PR07MB6241.eurprd07.prod.outlook.com<https://groups.google.com/d/msgid/jallib/AM0PR07MB6241378E01DF90BC2AFE3E46E6F80%40AM0PR07MB6241.eurprd07.prod.outlook.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "jallib" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/136924260.2056558.1606476509299%40mail.yahoo.com<https://groups.google.com/d/msgid/jallib/136924260.2056558.1606476509299%40mail.yahoo.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "jallib" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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