Hi Maarten,
I want to know more about SDCC internal information,such as the SDCC
compile flow,What is the difference between SDCC and GCC
how SDCC combine the front-end with back-end,will SDCC generate RTL stuff
like that?
I know you are a superior,so could u give me some detail materials?
Thanks!
Donald
2011/3/22 Maarten Brock <sourceforge.br...@dse.nl>
> Hi,
>
> Keil uses a very strange symbols (^, =) to define a bit in an sfr. To
> standard C they mean 'xor' and 'assign' and thus SDCC treats them as such.
>
> sbit P10 = P1^0;
>
> SDCC sees a definition of an sbit called P10 and it is INITIALIZED with
> the value of P1 XOR 0x00. The value of sfr P1 is not constant.
>
> For a proper definition of the sbit see the SDCC manual how SDCC expects
> things.
>
> Maarten
>
> > Hi Donald,
> >
> > The keyword 'sbit' is used to define special function bits, much like
> > the keyword 'sfr' for the special function registers. The good news is
> > that most of the SFRs in 8051 are already defined in <8051.h> Thus to
> > set the 4th bit of PORT-2 to 0, use the following code:
> >
> > #include <8051.h>
> >
> > void main (void)
> > {
> > P2_3 = 0; // P2_0 is the first bit of port 2
> > }
> >
> > This is not standard C. Thus Keil and SDCC may follow different
> > conventions.
> >
> > Krish
> >
> > 2011/3/22 duck donal <tangtao87657...@gmail.com>:
> >> Hi All,
> >> I'm a newbie for sdcc.
> >> A few days ago, I was in use of SDCC, ran into a problem.
> >>
> >> Program (bee.c) is very simple, as follows:
> >> #include<reg51.h>
> >> #include<stdio.h>
> >> sbit P10=P1^0;
> >> sbit P17=P1^7;
> >> int main(void)
> >> {
> >> unsigned char j;
> >> unsigned int i;
> >> while(1){
> >> P17=1;
> >> while(P17==0)
> >> {
> >> for(i=1;i<=500;i++)
> >> {
> >> P10=~P10;
> >> for(j=0;j<=50;j++);
> >> }
> >> for(i=1;i<=250;i++)
> >> {
> >> P10=~P10;
> >> for(j=0;j<=100;j++);
> >> }
> >> }
> >> }
> >> return 0;
> >> }
> >> My compiler option was sdcc -mmcs51 bee.c
> >> But SDCC gave me such an error message : bee.c:3:error
> >> 2:Initializer
> >> element is not constant
> >>
> >> bee.c:4:error 2:Initializer element is not constant
> >> It means the expression: sbit P10=P1^0 was wrong.
> >> I used keil C running the program,it compiled successfully,no
> >> errors,no warnings.
> >> Later,I got other programs to compile with SDCC.I found that where
> >> there is sbit instructions, there is error 2:Initializer element is not
> >> constant
> >> But keil C still can compile successfully.
> >> So,what is the solutions?To modify the program?How to do it? Or
> >> modify
> >> the sdcc?
> >> thanks£¡
> >> Donald
> >>
> >>
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