shuffle.c

// clang -emit-llvm -c -o shuffle.bc shuffle.c
// llvm-dis < shuffle.bc | less
// llc -march=c -o shuffle.cbe.c shuffle.bc
// clang -emit-llvm -c -o shuffle.cbe.bc shuffle.cbe.c
// llvm-dis < shuffle.cbe.bc | less
// llc -march=c -o shuffle.cbe.cbe.c shuffle.cbe.bc
// wdiff -w (set_color red) -x (set_color normal) -y (set_color green) -z (set_color normal) shuffle.cbe.c shuffle.cbe.cbe.c | less --raw

#include <stdio.h>
#include <stdlib.h>

void swap(char* lhs, char* rhs){
  char tmp = *lhs; *lhs = *rhs; *rhs = tmp;
}

void shuffle(char letters[], int length){
  for(int i=0; i<length; ++i)
    swap(&letters[i], &letters[i + rand() % (length - i)]);
}

int main(){
  srand(time(0));
  char letters[] = "abcdefghijklmnopqrstuvwxyz";
  shuffle(letters, 26);
  letters[10] = 0;
  printf("%s\n", letters);
}