xtea: Test inplace decryption

Based on test code by: Giorgio Vazzana <mywing81@gmail.com>
Signed-off-by: Martin Storsjö <martin@martin.st>

libavutil/xtea.c

@@ -160,14 +160,28 @@ static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
 int main(void)
 {
     AVXTEA ctx;
-    uint8_t buf[8];
+    uint8_t buf[8], iv[8];
     int i;
+    const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
+    uint8_t ct[32];
+    uint8_t pl[32];
 
     for (i = 0; i < XTEA_NUM_TESTS; i++) {
         av_xtea_init(&ctx, xtea_test_key[i]);
 
         test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
         test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
+
+        /* encrypt */
+        memcpy(iv, "HALLO123", 8);
+        av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
+
+        /* decrypt into pl */
+        memcpy(iv, "HALLO123", 8);
+        test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
+
+        memcpy(iv, "HALLO123", 8);
+        test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
     }
     printf("Test encryption/decryption success.\n");