Add several bit manipulation functions to C language

Jacktang

Add several bit manipulation functions to C language [Copy link]

There are instructions in assembly language that operate on bits directly, such as setting, resetting, inverting, testing a certain bit, etc., which are very convenient for hardware operations. Although C language also provides some bit operation methods, such as bitwise AND, bitwise OR, bitwise inversion, etc., they operate on a byte. If you want to operate on a specific bit, it is still inconvenient. The following are some functions that can imitate some bit operation functions of assembly language.

#define uchar unsigned char

/* Test whether a bit of the variable is ' 1 ', return true if it is, otherwise return false, num is the number to be tested, bit is the number of bits, its value ranges from 0 to 7 , the same below */

uchar bittest(uchar num, uchar bit)

{ if(num>>bit&0x01==1)

return 1;

else

return 0;

}

uchar bitclr(uchar num,uchar bit) /* clear a bit */

{

uchar bit_value[]={1,2,4,8,16,32,64,128};

return num&~bit_value[bit];

}

uchar bitset(uchar num,uchar bit) /* Set a bit */

{

uchar bit_value[]={1,2,4,8,16,32,64,128};

return num|bit_value[bit];

}

uchar bitcpl(uchar num,uchar bit) /* Invert a bit */

{

uchar bit_value[]={1,2,4,8,16,32,64,128};

if(num>>bit&0x01==1)

return num&~bit_value[bit];

else

return num|bit_value[bit];

}

/* The following main program demonstrates that when calling, you can directly give a value or a variable name */

void main(void)

{

fly xx=0xfe;

xx=bitset(xx,0);

printf("The set out is %x\n",xx);

printf("The clr out is %x\n",bitclr(255,0));

printf("The test out is %x\n",bittest(0xff,0));

printf("The cpl out is %x\n",bitcpl(0x00,7));

}

The above is the main program written using TC as an example. The functions are also available in other C languages.