If user supplies full 32 digit cid (chksum included) use it as is without recalculating the checksum (unless they also want a new serial including in it). User request for a device that appears to always want a 00 checksum.

.gitignore

@@ -0,0 +1,2 @@
+obj
+

README.md

@@ -12,7 +12,7 @@ device - sd card block device e.g. /dev/block/mmcblk1
 cid - new cid, must be in hex (without 0x prefix)
   it can be 32 chars with checksum or 30 chars without, it will
   be updated with new serial number if supplied, the checksum is
-  always recalculated
+  (re)calculated if not supplied or new serial applied
 serial - optional, can be hex (0x prefixed) or decimal
   and will be applied to the supplied cid before writing
 ```

jni/evoplus_cid.c

@@ -124,7 +124,7 @@ void main(int argc, const char **argv) {
 		printf("cid - new cid, must be in hex (without 0x prefix)\n");
 		printf("  it can be 32 chars with checksum or 30 chars without, it will\n");
 		printf("  be updated with new serial number if supplied, the checksum is\n");
-		printf("  always recalculated\n");
+		printf("  (re)calculated if not supplied or new serial applied\n");
 		printf("serial - optional, can be hex (0x prefixed) or decimal\n");
 		printf("  and will be applied to the supplied cid before writing\n");
 		printf("\n");
@@ -152,13 +152,15 @@ void main(int argc, const char **argv) {
 		*((int*)&cid[9]) = htonl(parse_serial(argv[3]));
 	}
 
-	// calculate checksum
-	cid[15] = crc7(cid, 15);
+	// calculate checksum if required
+	if (len != 32 || argc == 4) {
+		cid[15] = crc7(cid, 15);
+	}
 
 	// open device
 	fd = open(argv[1], O_RDWR);
 	if(fd < 0){
-		printf("[-] wtf\n");
+		printf("Unable to open device %s\n", argv[1]);
 		return;
 	}
 

libs/.gitignore

@@ -0,0 +1,4 @@
+*
+!.gitignore
+!armeabi
+