Repetition macros for C preprocessor. Inspired by https://stackoverflow.com/a/53110569

main.c

#include "rep.cpp"
#include <stdio.h>

int main(void) {
  unsigned num = 0;

  // Repeat the block 1011_2 = 11 times.
  REP4(1, 0, 1, 1, {
    printf("%u\n", num++);
  })
}

rep.cpp

#define IF0(m)
#define IF1(m) m

#define DUP1(m) m m
#define DUP2(m) DUP1(DUP1(m))
#define DUP3(m) DUP1(DUP2(m))

#define REP1(b0, m) { IF##b0(m) }
#define REP2(b1, b0, m) { IF##b1(DUP1(m)) REP1(b0, m) }
#define REP3(b2, b1, b0, m) { IF##b2(DUP2(m)) REP2(b1, b0, m) }
#define REP4(b3, b2, b1, b0, m) { IF##b3(DUP3(m)) REP3(b2, b1, b0, m) }