xtea: invert branch and loop precedence

Should slightly improve performance depending on the compiler used.
13 years ago · f6687bf5f8
parent 669bbedfa8
commit f6687bf5f8
1 changed files with 12 additions and 7 deletions
--- a/libavutil/xtea.c
+++ b/libavutil/xtea.c
@ -71,8 +71,8 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
 {
    int i;

-    while (count > 0) {
    if (decrypt) {
+        while (count > 0) {
            xtea_crypt_ecb(ctx, dst, src, decrypt);

            if (iv) {
@ -80,7 +80,13 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
                    dst[i] = dst[i] ^ iv[i];
                memcpy(iv, src, 8);
            }
+
+            src   += 8;
+            dst   += 8;
+            count -= 8;
+        }
    } else {
+        while (count > 0) {
            if (iv) {
                for (i = 0; i < 8; i++)
                    dst[i] = src[i] ^ iv[i];
@ -89,12 +95,11 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
            } else {
                xtea_crypt_ecb(ctx, dst, src, decrypt);
            }
-        }
-
            src   += 8;
            dst   += 8;
            count -= 8;
        }
+    }
 }

 #ifdef TEST