Separating a 32 bit address into parts

Question

In C, If I have a 32 bit binary address, how could I take bits 6 - 10 (5 bit value) and assign them to a new variable? For example, the address: 00000001001010011000100100100011

I want to take this section:

0000000100101001100010 01001 00011

And store it in a variable, x.

Note that it's bits 5 to 9, not 6 to 10. Bits are numbered from 0. — paddy, Feb 16 '21 at 07:34
duplicates: [How to read/write arbitrary bits in C/C++](https://stackoverflow.com/q/11815894/995714), [How do I extract specific 'n' bits of a 32-bit unsigned integer in C?](https://stackoverflow.com/q/8011700/995714), [How to get specific bit segments of an integer in C?](https://stackoverflow.com/q/29959338/995714)... — phuclv, Feb 16 '21 at 10:45
VTRO OP wants to isolate address bits, not just integer bits. — chux - Reinstate Monica, Feb 16 '21 at 16:56

chux - Reinstate Monica · Answer 1 · 2021-02-16T17:08:36.643

If I have a 32 bit binary address, how could I take bits 6 - 10 (5 bit value)

Addresses are not really something that have arithmetic values in particular bits - that is very implementation dependent. Code can convert an address to an integer type and then proceed.

OP apparently wants other @paddy bits: 9 to 5.

#include <stdint.h>

void *ptr = ....;
uintptr_t i = (uintptr_t) ptr;

//           v------v         Ignore 5 least significant bits, move all bits right by 5. 
unsigned x = (i >> 5) & 0x1F;
//                      ^--^  Mask: Only retain 5 bits.

Separating a 32 bit address into parts

1 Answers1