Rockchip rk27xx utils

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29936 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 46 insertions, 0 deletions

diff --git a/utils/rk27utils/rk27load/scramble.c b/utils/rk27utils/rk27load/scramble.c
new file mode 100644
index 0000000000..7e5b1518d7
--- /dev/null
+++ b/utils/rk27utils/rk27load/scramble.c
@@ -0,0 +1,46 @@
+#include <stdint.h>
+#include "scramble.h"
+
+void scramble(uint8_t *in, uint8_t *out, const int size)
+{
+    /* table extracted from bootrom */
+    static const uint8_t key[] = {
+        0x7C, 0x4E, 0x03, 0x04,
+        0x55, 0x05, 0x09, 0x07,
+        0x2D, 0x2C, 0x7B, 0x38,
+        0x17, 0x0D, 0x17, 0x11
+    };
+
+        int i, i3, x, val, idx;
+
+        uint8_t key1[0x100];
+        uint8_t key2[0x100];
+
+        for (i=0; i<0x100; i++) {
+                key1[i] = i;
+                key2[i] = key[i&0xf];
+        }
+
+        i3 = 0;
+        for (i=0; i<0x100; i++) {
+                x = key1[i];
+                i3 = key1[i] + i3;
+                i3 += key2[i];
+                i3 &= 0xff;
+                key1[i] = key1[i3];
+                key1[i3] = x;
+        }
+
+        idx = 0;
+        for (i=0; i<size; i++) {
+                x = key1[(i+1) & 0xff];
+                val = x;
+                idx = (x + idx) & 0xff;
+                key1[(i+1) & 0xff] = key1[idx];
+                key1[idx] = (x & 0xff);
+                val = (key1[(i+1)&0xff] + x) & 0xff;
+                val = key1[val];
+                out[i] = val ^ in[i];
+        }
+}
+