diff --git a/kpack_c.c b/kpack_c.c
index b551353..e9a526f 100644
--- a/kpack_c.c
+++ b/kpack_c.c
@@ -41,7 +41,7 @@ unsigned pack_lzma(unsigned char *infile, unsigned char *outfile, unsigned insiz
     return outsize - 1;
 }
 
-unsigned preprocess_calltrick(unsigned char *infile, unsigned insize, unsigned char ct1[256], unsigned *ct, unsigned char *ctn)
+unsigned preprocess_calltrick(unsigned char *infile, unsigned insize, unsigned char ct1[256], unsigned *ctn, unsigned char *cti)
 {
     // TODO: check
     unsigned char *buf = malloc(2*insize);
@@ -81,10 +81,20 @@ unsigned preprocess_calltrick(unsigned char *infile, unsigned insize, unsigned c
         
     } while(count > 0);
 
+    *ctn = edx;
+    unsigned idx = 0;
+    while (idx < 256 && ct1[idx] != 0) {
+        idx++;
+    }
+    if (idx >= 256) {
+        goto pack_calltrick_fail;
+    }
+    *cti = ~(unsigned char)256;
+
     // TODO !
 
     pack_calltrick_fail:
-    // ...
+    // TODO
 }
 
 
@@ -216,7 +226,7 @@ int main(int argc, char *argv[])
     outfilebest = outfile;
     unsigned method = METHOD_LZMA;
 
-    unsigned char ct1[256];
+    unsigned char ct1[256]; // TODO zero out or place it zeroable space
     unsigned ctn;
     unsigned char cti;