This paper describes a scalable, highly portable, and power-efficient generator for massive multiple-input multiple-output (MIMO) uplink baseband processing. This generator is written in Chisel, and produces hardware instances for the distributed processing in a scalable massive MIMO system. The generator is parameterized in both the MIMO system and hardware datapath elements. The performance of several generator instances with different parameter values are validated by emulation on a field-programmable gate array (FPGA), demonstrating both functionality and scalability, and operation up to 6.4Gb/s data throughput.