Re: extended assembly

[Herbert Poetzl <herbert@13thfloor.at>]

On Wed, Jul 06, 2005 at 07:18:48PM +0000, Martin Fflores wrote:
> hi! everyone, i have a rare problems here, i dont know if i do somethign 
> wrong or the compiler have some problems, when i read a value from a port(a 
> byte) the first time it's retun to me a byte so i catch and use printf to 
> show this value, the secon time its return to me a integer value or a dont 
> know, let me give you a example:
> 
> char value=0;
> __asm__ __volalile__("cli;inb $0x60,%0;sti;":"=r"(value));
> printf("%x",value);// the first time usually return 1c
> // this is the second time
> __asm__ __volalile__("cli;inb $0x60,%0;sti;":"=r"(value));
> printf("%x",value);// this print in teh screen ffffffa ainteger value
> 
> i'm expecting a ACK response for the keyboard ACK is in the ffffffa the 
> first byte buti cant never know ir caouse when i ask for ack it inst ack in 
> ffffffa and it is bigger than a byte why iot happend??????????????????''

man 3 printf

       o,u,x,X   The unsigned int argument is converted to unsigned 
		     ~~~~~~~~~~~~~~~~~~~~~
		 octal (o), unsigned decimal (u), or unsigned hexadecimal
		 (x and X) notation. 

The length modifier
       hh        A following integer conversion corresponds to a 
		 signed char or unsigned char argument, or a
              	 following n conversion corresponds to a pointer 
		 to a signed char argument.

the 'char' value is signed, and is implicitely converted
to an int, which in turn is printed as unsigned hex 'x'

 0xfa (-5) -> 0xfffffffa

best,
Herbert

> Take Care Folks.
> 
> Martin Flores
> 
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