Comparing unsigned char bits. Post: 302624759

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Top Forums Programming Comparing unsigned char bits. Post 302624759 by agama on Monday 16th of April 2012 07:48:37 PM

04-16-2012

Registered User

Here is a quick example of setting and checking a bit vector based on 255 possible combinations:

Code:

#include "stdio.h"
#include "stdlib.h"

#define VSIZE  256/8            // vector size in bytes
void mark( unsigned char *vector, unsigned char byte )
{
    int idx;
    int mask;

    idx = byte / 8;
    mask = 1 << (byte % 8);

    vector[idx] |= mask;
}

int check( unsigned char *vector, unsigned char byte )
{
    int idx;
    int mask;

    idx = byte / 8;
    mask = 1 << (byte % 8);

    return vector[idx] & mask;
}

int main( int argc, char **argv )
{
    unsigned int    value;
    unsigned char vector[VSIZE];

    printf( "enter non-number or ctl-D to quit\n" );
    for( ; ; )
    {
        printf( "enter a number (0-255): " );
        if( scanf( "%u", &value ) <= 0 )        // read value converting it to unsigned
        {
            printf( "\n" );
            exit( 0 );
        }
        if( value < 256 )
        {
            printf( "the value %u has %sbeen entered before\n", value, check( vector, value ) ? "" : "not " );
            mark( vector, value );
        }
        else
            printf( "%d is out of range for a byte\n", value );
    }

    return 0;
}

Last edited by agama; 04-16-2012 at 09:11 PM.. Reason: typo

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LEARN ABOUT DEBIAN

dpgen_adsb2f

DPGEN_ADSB2F(3) 					  Alliance - genlib User's Manual					   DPGEN_ADSB2F(3)

NAME

       DPGEN_ADSB2F - Adder/Substractor Macro-Generator

SYNOPSIS

       #include  <genlib.h>

       void GENLIB_MACRO (DPGEN_ADSB2F, char *modelname, long flags, long N);

DESCRIPTION

       Generate a N bits adder/substractor named modelname.

       How it works :

       o if the add_sub signal is set to '0' an addition is performed, otherwise it's a substraction.

       o Operation can be either signed or unsigned. In unsigned mode c31 is the overflow, in unsigned mode you have to compute overflow by XORing
	 c31 and c30.

   TERMINAL NAMES
       1. add_sub : select addition or substraction (input, 1 bit).

       2. c31 : carry out. In unsigned mode, this is the overflow (output, 1 bits).

       3. c30 : used to compute overflow in signed mode : overflow := c31 xor c30 (output, 1 bits).

       4. i1 : first operand (input, N bits).

       5. i0 : second operand (input, N bits).

       6. q : output (N bits).

       7. vdd : power.

       8. vss : ground.

EXAMPLE

       GENLIB_MACRO(DPGEN_ADSB2F, "model_adsb2f_32"
				   , F_BEHAV|F_PLACE
				   , 32
				   );

       GENLIB_LOINS( "model_adsb2f_32"
		   , "instance1_adsb2f_32"
		   , "add_sub"
		   , "c32"
		   , "c31"
		   , "i1[31:0]"
		   , "i0[31:0]"
		   ,  "q[31:0]"
		   , "vdd", "vss", NULL
		   );

SEE ALSO

       GENLIB_MACRO(3), genlib(1)

ASIM
/LIP6							   30 July 2004 						   DPGEN_ADSB2F(3)