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

[Weddington, Eric]

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> org] On Behalf Of David VanHorn
> Sent: Tuesday, March 10, 2009 10:01 AM
> To: AVR-GCC
> Subject: [avr-gcc-list] Wierd Calls.
> 
> I'm probably doing something wrong again.. 
>  
> I've seen this on and off, as I'm stepping through the 
> compiled code in the asm window.
> I will have a call that makes no sense to me, sort of 
> randomly appearing as I change the code, and dissapearing for 
> no obvious reason.  It's always to the lcd_init routine, even 
> though this code has nothing to do with the LCD... 
>  
> Below is where it's currently happening.
> This SHOULD just load BIN with a value between 0 and 31.
> It has to pull data from Raw_Data[0] according to the value 
> of Raw_Data_Index which will be between 0 and 511.   
> Raw_Samples is 512, and Sample_Bins is 32.
>  
> 1051:      Bin = (Raw_Data[0][Raw_Data_Index]) / (Raw_Samples 
> / Sample_Bins); // Find the bin for the old raw data
> +0000031B:   90C00076    LDS       R12,0x0076     Load direct 
> from data space
> +0000031D:   90D00077    LDS       R13,0x0077     Load direct 
> from data space
> +0000031F:   01F6        MOVW      R30,R12        Copy register pair
> +00000320:   53EC        SUBI      R30,0x3C       Subtract immediate
> +00000321:   4FFF        SBCI      R31,0xFF       Subtract 
> immediate with carry
> +00000322:   8180        LDD       R24,Z+0        Load 
> indirect with displacement
> +00000323:   E06F        LDI       R22,0x0F       Load immediate
> +00000324:   940E062C    CALL      0x0000062C     Call subroutine
> +00000326:   2FA8        MOV       R26,R24        Copy register
> +00000327:   E0B0        LDI       R27,0x00       Load immediate

If I had to guess, I would guess that this is a word address / byte address 
issue and what it is really calling is math subroutines in libgcc.

Use the -save-temps switch and look at the <file>.s filt that is generated to 
see what the compiler is outputting for the section of code above. That should 
shed some light on which function it thinks its calling.