Dynamic sharing of RAM in a software-defined communication system includes storing program code in a flash memory, categorizing parts of the code into groups of transmit categories according to when a part of the code needs to be copied into a section of a RAM and then executed during a first state of a TX state machine and according to how another part of the code can be later fit into the same section and then executed during a second state. Similarly, parts of the code are categorized into groups of receive categories according to when a part of the code needs to be copied into a section of RAM and then executed during a first state of a RX state machine and according to how another part of the code can be later fit into that section and then executed during a second state of the RX state machine, to reduce the amount of RAM without sacrificing speed performance.