id3v2: reduce the scope of some non-globally-used symbols/structures

[ffmpeg] / libavutil / rc4.c

diff --git a/libavutil/rc4.c b/libavutil/rc4.c
index 0cf71a4194a2938af9a8d3f724d795e74ac2bc43..3bf710f3f1738642d88ba9e3da4ebe978e7f5def 100644 (file)
--- a/libavutil/rc4.c
+++ b/libavutil/rc4.c
@@ -4,29 +4,35 @@
  *
  * loosely based on LibTomCrypt by Tom St Denis
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
+#include "avutil.h"
 #include "common.h"
 #include "rc4.h"
 
-void ff_rc4_enc(const uint8_t *key, int keylen, uint8_t *data, int datalen) {
+typedef struct AVRC4 AVRC4;
+
+int av_rc4_init(AVRC4 *r, const uint8_t *key, int key_bits, int decrypt) {
     int i, j;
-    uint8_t x, y;
-    uint8_t state[256];
+    uint8_t y;
+    uint8_t *state = r->state;
+    int keylen = key_bits >> 3;
+    if (key_bits & 7)
+        return -1;
     for (i = 0; i < 256; i++)
         state[i] = i;
     y = 0;
@@ -36,13 +42,20 @@ void ff_rc4_enc(const uint8_t *key, int keylen, uint8_t *data, int datalen) {
         y += state[i] + key[j];
         FFSWAP(uint8_t, state[i], state[y]);
     }
-    // state initialized, now do the real encryption
-    x = 1; y = state[1];
-    while (datalen-- > 0) {
+    r->x = 1;
+    r->y = state[1];
+    return 0;
+}
+
+void av_rc4_crypt(AVRC4 *r, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt) {
+    uint8_t x = r->x, y = r->y;
+    uint8_t *state = r->state;
+    while (count-- > 0) {
         uint8_t sum = state[x] + state[y];
         FFSWAP(uint8_t, state[x], state[y]);
-        *data++ ^= state[sum];
+        *dst++ = src ? *src++ ^ state[sum] : state[sum];
         x++;
         y += state[x];
     }
+    r->x = x; r->y = y;
 }