xtea: Factorize testing into a separate function

Based on a patch by Michael Niedermayer.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavutil/xtea.c

@@ -139,6 +139,25 @@ static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
 };
 
+#undef exit
+static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
+                      const uint8_t *ref, int len, uint8_t *iv, int dir,
+                      const char *test)
+{
+    av_xtea_crypt(ctx, dst, src, len, iv, dir);
+    if (memcmp(dst, ref, 8*len)) {
+        int i;
+        printf("%s failed\ngot      ", test);
+        for (i = 0; i < 8*len; i++)
+            printf("%02x ", dst[i]);
+        printf("\nexpected ");
+        for (i = 0; i < 8*len; i++)
+            printf("%02x ", ref[i]);
+        printf("\n");
+        exit(1);
+    }
+}
+
 int main(void)
 {
     AVXTEA ctx;
@@ -148,17 +167,8 @@ int main(void)
     for (i = 0; i < XTEA_NUM_TESTS; i++) {
         av_xtea_init(&ctx, xtea_test_key[i]);
 
-        av_xtea_crypt(&ctx, buf, xtea_test_pt[i], 1, NULL, 0);
-        if (memcmp(buf, xtea_test_ct[i], 8)) {
-            printf("Test encryption failed.\n");
-            return 1;
-        }
-
-        av_xtea_crypt(&ctx, buf, xtea_test_ct[i], 1, NULL, 1);
-        if (memcmp(buf, xtea_test_pt[i], 8)) {
-            printf("Test decryption failed.\n");
-            return 1;
-        }
+        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");
     }
     printf("Test encryption/decryption success.\n");