The block cipher SPECK128/128 written in one tweet

SPECK.c

#include <stdio.h>
typedef unsigned long long u64;

#define R(x,y,k)x=x>>8|x<<56,x+=y,x^=k,y=y<<3|y>>61,y^=x
void SPECK(u64 *T,u64 *K){
for(int i=0;i<32;){
 R(T[1],*T,*K);
 R(K[1],*K,i++);
}}

int main() {
    u64 key[2] = {0x0706050403020100, 0x0f0e0d0c0b0a0908};
    u64 text[2] = {0x7469206564616d20, 0x6c61766975716520};

    SPECK(text, key);

    printf("%llx %llx\n", text[1], text[0]);
    if (text[1] != 0xa65d985179783265 || text[0] != 0x7860fedf5c570d18) {
        printf("The code is wrong!\n");
    }

    return 0;
}

The original tweet is at https://twitter.com/zhuzhuor/status/566054090128773120