C for dummies, I need this book

[yogi]

So I got a question, and feel like it's a 'dumb' question, but what the hey, I spent the evening working it out and wanted some input.

 I'm messing with the 8x8 scan matrix for MIOS8, and am expanding it a bit for a little project. Was setting up variables for transposing note range and Midi out channel. 

At first tried adding to the display using 'pin' which is returned from the sm_ButtonHandler, but found it was out of scope in Display_tick(). So above Init() I added sm_button_pin and within SM_NotifyToggle() this:

       sm_button_pin=pin;

This works, with sm_button_pin being global. Then added vars for chan_out and note_offset

        unsigned char chan_out=0;

This seemed to work but when I tried to set it to 3 or what have you, no change. What I finally did was:

          unsigned char chan_out;

And in Init() added this:

           char_out=3;

 

So is there a better/cleaner way? I was thinking it should be in main.h rather then main.c but couldn't get it working; even tried to add sm-button-pin as an export from sm_simple.asm. My C skills are way behind compared to assembly, feeling bad it took so long just setting and using a variable! Are there any online refs for SDCC and C in general? Have a few dusty C++ books and a couple CCS C manuals, guess I'll have to clear of the cobwebs :)

Thanks,

Yogi

[TK.]

It would work with a common C flow (e.g. on a MIOS32 core), but it doesn't work with MIOS8 in conjunction with the quick&dirty SDCC adaption, because it doesn't take care about variable preloading and initializes all variables (which are not declared as a const) with 0

 

So, you are on the right track, there is no cleaner way with the MIOS8/SDCC combo.

 

Best Regards, Thorsten.

[yogi]

OK.thanks. The differences between standard C, CCS, MPLab C and SDCC in combination with my aging memory is a bad mix:)

Will have to spend some time with the SDCC docs, Thanks again for your efforts, even though MIOS8 is 'old school', it is such a great package to work with:)

yogi