RE: [avr-gcc-list] Re: Wierd Calls.

[Weddington, Eric]

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> org] On Behalf Of David VanHorn
> Sent: Wednesday, March 11, 2009 8:24 AM
> To: AVR-GCC
> Subject: Re: [avr-gcc-list] Re: Wierd Calls.
> 
>  
> Well.. Still flogging the horse here. 
>  
>  
>  
> I have the .S file, but I don't know how to interpret it.

It's the assembly output from the compiler. It goes straight into gas and out 
comes your object code.


>  
> I carved up the statement even further, and moved the 
> declarations so all the vars are in ram so I can watch them easily.
>  
>  A = Raw_Data[0][Raw_Data_Index];         //  Gives the 
> expected result.
>  Bin = (A / Data_Divisor);                         // Gives 
> nonsense, AND trashes data in ram!
>  
> Here's the asm output.  The first line is what I'd expect.

That's not the asm output. That is a listing, because of the addresses on the 
side.
  
> 1072:      A = Raw_Data[0][Raw_Data_Index];         // Get 
> the old data
> +00000337:   91C00076    LDS       R28,0x0076     Load direct 
> from data space
> +00000339:   91D00077    LDS       R29,0x0077     Load direct 
> from data space
> 
> The second one starts out normally, but then this call to 
> 0x622, which is hosing everything.
>  
> 1073:      Bin = (A / Data_Divisor);          // Find the bin 
> for the old raw data
> +0000033B:   01FE        MOVW      R30,R28        Copy register pair
> +0000033C:   5FE2        SUBI      R30,0xF2       Subtract immediate
> +0000033D:   4FFE        SBCI      R31,0xFE       Subtract 
> immediate with carry
> +0000033E:   8180        LDD       R24,Z+0        Load 
> indirect with displacement
> +0000033F:   E090        LDI       R25,0x00       Load immediate
> +00000340:   E06F        LDI       R22,0x0F       Load immediate
> +00000341:   E070        LDI       R23,0x00       Load immediate
> +00000342:   940E0622    CALL      0x00000622     Call subroutine

What does the .S file show for the code snippet above? That's what we're trying 
to get at.