Re: RE: [avr-gcc-list] buggy variable naming with underscores

[Jamie Morken]

Hi Ben,

----- Original Message -----
From: Ben Mann <address@hidden>
Date: Monday, March 14, 2005 4:34 pm
Subject: RE: [avr-gcc-list] buggy variable naming with underscores

> Hi Jamie,
> 
> Um, the code below would indeed cause the problem you mention.  
> Instead try
> 
> ADChannels[nNextAdc]=(((u16)ht)<<8)|lt;       
> 
> And it should work properly, requiring 
> 
> printf("x: %i\r\n", (int)(ADChannels[0]);
> 
> to print out channel 0.

That is what the code was originally, and all the channels were shifted one bit!

cheers,
Jamie

> 
> If you work through your code you will see that on the next call 
> to the
> signal after setting nNextAdc=0, you will be writing
> ADChannels[-1]
> which is going to scribble memory somewhere; it also explains why 
> you are
> then reading index -1 to get the byte.
> 
> Ben Mann
> 
> --snip!--
> 
> SIGNAL(SIG_ADC) 
> { 
> u08 lt; 
> u08 ht; 
> lt=inp(ADCL); 
> ht=inp(ADCH)& 0x03; 
> ADChannels[nNextAdc-1]=(((u16)ht)<<8)|lt;     
> nNextAdc++;
> if (nNextAdc==8) nNextAdc=0;
> outp(nNextAdc,ADMUX); 
> } 
> 
> I try to store the 8 channels into an array but all 8 channels are 
> shiftedone index in the array when I print them out. ie.
> printf("x: %i\r\n", (int)(ADChannels[0]);
> 
> this prints out ADC channel 1 unless I subtract 1 from nNextAdc 
> like above.
> 
> so the index 0 is ADC channel 1 instead of ADC channel 0.  So the 
> "solution"I used was to write to index -1 to 7, and somehow this 
> corrected the
> problem, but then I was also corrupting other memory I guess! :)  
> Any sample
> code that continously logs all 8 ADC channels to an array? (without
> corrupting memory!)
> 
> 
> 
>