/* From: https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm */
#include <stdint.h>

void encrypt (uint32_t* v, uint32_t* k) {
	uint32_t v0=v[0], v1=v[1], sum=0, i;           /* set up */
	uint32_t delta=0x9e3779b9;                     /* a key schedule constant */
	uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3];   /* cache key */
	for (i=0; i < 32; i++) {                       /* basic cycle start */
		uint32_t tmp_a, tmp_b, tmp_c;
		sum += delta;
		tmp_a = (v1<<4) + k0;
		tmp_b = v1 + sum;
		tmp_c = (v1>>5) + k1;
		v0 += tmp_a ^ tmp_b ^ tmp_c;
		tmp_a = (v0<<4) + k2;
		tmp_b = v0 + sum;
		tmp_c = (v0>>5) + k3;
		v1 += tmp_a ^ tmp_b ^ tmp_c;
	}                                              /* end cycle */
	v[0]=v0; v[1]=v1;
}

void decrypt (uint32_t* v, uint32_t* k) {
	uint32_t v0=v[0], v1=v[1], sum=0xC6EF3720, i;  /* set up */
	uint32_t delta=0x9e3779b9;                     /* a key schedule constant */
	uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3];   /* cache key */
	for (i=0; i<32; i++) {                         /* basic cycle start */
		uint32_t tmp_a, tmp_b, tmp_c;
		tmp_a = (v0<<4) + k2;
		tmp_b = v0 + sum;
		tmp_c = (v0>>5) + k3;
		v1 -= tmp_a ^ tmp_b ^ tmp_c;
		tmp_a = (v1<<4) + k0;
		tmp_b = v1 + sum;
		tmp_c = (v1>>5) + k1;
		v0 -= tmp_a ^ tmp_b ^ tmp_c;
		sum -= delta;
	}                                              /* end cycle */
	v[0]=v0; v[1]=v1;
}