maarten wrote:
> Hello Peter,
>
> > In the main routine a printf gets the wrong value:
> >
> > extern __data uint8 * __data sys_rstack;
> >
> > // string for LCD output
> > #define STR_LEN 80
> > __xdata uint8 str[STR_LEN];
> >
> > main()
> > {
> > sprintf (str,"%x", (uint8) *sys_rstack);
> > lcd_print(2, str);
> >
> > generates:
> > 707 ; main.c:107: sprintf (str,"%x",
> > (uint8) *
> > sys_rstack);
> > 01B4 A9 10 708 mov r1,_sys_rstack
> > 01B6 87 07 709 mov ar7,@r1
> > 01B8 C0 07 710 push ar7
> > 01BA 74 53 711 mov a,#__str_3
> > 01BC C0 E0 712 push acc
> > 01BE 74 7E 713 mov a,#(__str_3 >> 8)
> > 01C0 C0 E0 714 push acc
> > 01C2 74 80 715 mov a,#0x80
> > 01C4 C0 E0 716 push acc
> > 01C6 74 DC 717 mov a,#_str
> > 01C8 C0 E0 718 push acc
> > 01CA 74 01 719 mov a,#(_str >> 8)
> > 01CC C0 E0 720 push acc
> > 01CE E4 721 clr a
> > 01CF C0 E0 722 push acc
> > 01D1 12 7D 15 723 lcall _sprintf
> > 01D4 E5 81 724 mov a,sp
> > 01D6 24 F9 725 add a,#0xf9
> > 01D8 F5 81 726 mov sp,a
> > 727 ; main.c:108: lcd_print(2, str);
> >
> > The code above appears to be loading the contents of
> > sys_rstack (at 0x10 in data) in to r7 but something undesirable happens
> > after that (which may well be operator error on my part).
>
> Since you use an explicit cast to char on the parameter passed to a
> varargs function (sprintf) the value is not passed as an int as normal.
> This is an extension to save memory. But then your formatter must also
> tell it to expect a char instead of an int as %x does. Maybe it's better
> to just remove the inline cast.
what difference does the cast make? the declaration is already
uint8, so isn't the cast a no-op? what am i missing?
this sdcc behavior bites us (bytes us? :-) all the time -- i'm always
having to go back to add "(uint)foo" casts when printing byte-wide
values as %x or %d, to make the values show correctly. unless there
are new format chars for byte-wide parameters, how does this save
memory?
what am i missing?
paul
>
> HTH,
> Maarten
>
=---------------------
paul fox, p...@laptop.org
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