-void CAST_cfb64_encrypt(in, out, length, schedule, ivec, num, encrypt)
-unsigned char *in;
-unsigned char *out;
-long length;
-CAST_KEY *schedule;
-unsigned char *ivec;
-int *num;
-int encrypt;
+void CAST_cfb64_encrypt(const unsigned char *in, unsigned char *out,
+ long length, const CAST_KEY *schedule, unsigned char *ivec,
+ int *num, int enc)