How to manipulate bitwise an integer in c or ccs?

General solution in C

In general, to "erase" a bit, this is:

valor &= ~( 1 << bitPos);

and to "light up", that's it:

valor |= 1 << bitPos;

where bitPos is the position of the bit, zero being the rightmost one.

See working at IDEONE .

If you want to handle more than one bit at a time, you can do so too:

int valor   = 15 // 0b00001111;

int mascara = 70 // 0b01000101;
               //BIT: 76543210

resultado1 = valor |  mascara;  // 0b01001111 ("acendi"  os bits 0,2 e 6)
resultado2 = valor & ~mascara;  // 0b00001010 ("apaguei" os bits 0,2 e 6)

See working at IDEONE

Example:

int valor = 15 // 0b00001111;
valor &= ~( 1 << 0 );     // valor = 14 ( 0b00001110 ) - "apagamos"  o bit 0
valor |= 1 << 5;          // valor = 46 ( 0b00101110 ) - "acendemos" o bit 5
valor &= ~( 1 << 1 );     // valor = 44 ( 0b00101100 ) - "apagamos"  o bit 1
valor |= 1 << 0;          // valor = 45 ( 0b00101101 ) - "acendemos" o bit 0

CCS Functions

According to colleague Bruno, there are the functions bit_set(número, bit) and bit_clear(número, bit) , see corresponding answer.

Of curiosity, if it were for Arduino:

Just to complement, if anyone is interested in Arduino equivalent, we have functions similar to those of CCS:

link

We have these two functions:

• bitSet(x, n)

• bitClear(x, n)

Since x is the value to be changed, and n is the bit to be changed, 0 is the rightmost bit.

CCS has the functions bit_set(número, bit) , which sets the bit to 1 and bit_clear(número, bit) , which sets the bit to 0 !