For my port of EHBASIC I have needed (and attempted to implement) LOAD and SAVE commands that took string arguments. I'm not really getting it to work right, probably because I'm missing something incredibly simple and stupid. :/

This is because my target is a disk system (I am running it under an OS).

(Feel free to lock, I figured it out - it was JSR LAB_EVEX. I'm still working on the graft though.)

All --

I know this is an old thread, but I'm up to the point where I'm writing the "disk" save and load commands on my implementation of SBC2. I've seen several recommended methods to get a string parameter, but none seem to work. The command is {DSAVE "filename"} with a maximum string length of 16 characters (due to limits in Commodore DOS). The "str_xx" variables are my own. The SETNAM routine is a DOS routine that sets the file name parameters for DOS.


When I look at the string that's pointed to by the registers upon returning from LAB_EVST, it points to "Ready". Clearly that's not right. I've tried the other methods, with no success. At this point, I'm a bit stuck. There must be a step that I'm missing somewhere. I've looked at some of the other string-based commands for ideas, but that's not helping either. Maybe someone with more experience can point to where I'm going wrong.

Thanks again!

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Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

Hi Rich,

I am including a copy of my routines I use to interface EhBASIC to my DiskOS. I used it to pass load and save parameters back and forth. The pscan routine scans through an EhBASIC program to find the end, and then sets EhBASIC's pointers properly.

Hope this helps.

Daryl

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Please visit my website -> https://sbc.rictor.org/

Thanks Daryl. The version you sent is different than what I have so I will look more closely. I guess what I'm not getting is when you enter <DSAVE"FILENAME"> from BASIC, where can I get the string within the quotes? The addresses I can access in memory...I just can't get the string.

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Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

The input line should still be at ibuffs. You may need to parse it to find the start quote and end quote. I zero out the ibuffs as I read it to prevent EhBASIC from trying to execute the rest of the line after the save command is executed. It's been a while since I worked on that code, but I think that's all there was to it. In my case, the syntax was SAVE filename<cr>. I could add a path prefix also, SAVE /sub/filename<cr>. EhBASIC's parser replaced the / with $B9 so my code put the / back in.

You can have the SAVE command just jump to you monitor then you can view the memory contents at ibuffs to confirm my description. It's possible the EhBASIC parser is moving the quoted filename to some string buffer if it's not still at ibuffs. I would expect there to be a pointer in the ibuffs area to that string, but I never dug that deep into EhBASIC.

Daryl

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Please visit my website -> https://sbc.rictor.org/

No, str_pl & str_ph are not your own!

They are also used in ehbasic to print "Ready" at the end of a direct command, hence they obviously will point at "Ready" when you look at them after a direct command.

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6502 sources on GitHub: https://github.com/Klaus2m5

Thanks Klaus. I did look back at my code and my "...variables are my own..." comment is actually wrong. I confused the variable name when typing the posting. However, what you describe is what's happening. I am using the "str_xx" variables as inputs to a routine which takes the string pointed to by YX as the filename string.

So, I'm at least using the wrong string variables from the parser. So, what is the right routine to use to parse a string in quotes (or not...I don't have to use quotes) from the command line and get a pointer to it?

Thanks.

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Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

The first question is, if you really need to go through a full string evaluation, as you would probably never allow a string variable as a parameter of a SAVE or LOAD. Parsing a simple string constant should be easy, as you just need to look for an opening quote. The string should then be at Bpntrl/h + 1 and is terminated by closing quotes. See LAB_INPUT, how ehbasic prints a string constant if available.

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6502 sources on GitHub: https://github.com/Klaus2m5

Klaus --

You are correct, it's a string constant. What I was missing was the correct system variable to use. Thanks again!

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Rich Cini
Build Master and maintainer of the Altair32 Emulation project
http://cini.classiccmp.org
http://altair32.classiccmp.org

Menu-program launching and semi-automated chaining come to mind ...

Mike

A LOAD in EhBASIC requires a subsequent RUN. So keeping variables between chained program parts is not possible. However, chaining itself would still be possible if you can manage to inject a RUN, just not with a filename stored in a variable.

Same goes for a program menu. You just can't pass variables back and forth.

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6502 sources on GitHub: https://github.com/Klaus2m5

Hi there,

there seems to be quite a lot of mixed information about how to deal with string arguments in LOAD and SAVE. I'd like to present the way I came up with:
At the beginning of either LOAD and SAVE, i call a subroutine that gets the string argument using LAB_EVEX and opens the file:


As it seems, after calling LAB_EVEX, ssptr points to the string given as parameter including the closing ", which I overwrite with $00 to be compatible with my open routine, which expects the address of a null terminated string.
In another thread, it was suggested to pop the string from the descriptor stack using LAB_22B6, which in my case resulted in ut1_ph/l not pointing to the string, but anywhere in the area of $exxx, where my os resides. So I went for the above approach. It works, but it feels rather dirty due to the overwriting of the closing ". At this point, I am open for suggestions.

EDIT:
BTW, my first approach was to just use Bpntrl as suggested above but this way SAVE always gave me a Syntax Error after having saved the file anyway. As this gave me a really hard time to track down, I went for the somewhat oversized approach using LAB_EVEX together with a bit of dirt as described above.

/thomas

Old post, but this is my code, jumped to via SAVE_VEC and LOAD_VEC:

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JGH - http://mdfs.net

Thanks, that really helped to make my version a lot less messy