Hi Oleg,
The code keyword causes your constants to be stored in code space and therefore your code size should always increase by the number of bytes stored.

If your code size went down by moving the constants from xdata to code it is not because of constant storage reasons. Most likely it is the data accesses to the constants.

All movc instructions are one byte instructions, some mov instructions are 2 bytes and one is 3 bytes. So depending on how the compiler sets up the assembly code to move xdata versus code could cause smaller code from the movc versus the mov and movx combinations.

In any event, if you add constants to code you code size increases by the number of byte constants stored.

Allen