A small transpiler from netlist to C. Here is a link to the github repository.

To build run :

make

It will create an executable netlist_simulator which can be run with ./netlist_simulator [-s] <file> to output a file out.c. Once compiled it can be run with ./a.out [n] where n is the optional number of steps. By default the C program expects a rom directory where each x=ROM(...) has a corresponding file called x consiting in a sequence of zeros and ones (the ASCII characters). This behaviour can be changed by the -s option of netlist_simulator which toggles static mode. The rom files are now expected by the netlist_simulator program directly (in the same format) and are put in the C file. This has been implemented hoping that an optimizing C compiler could use the ROMs to further optimize the program.

The netlist_simulator creates, given a netlist, a C program which when compiled runs a loop which reads inputs, apply the logic given by the netlist and prints the value of the outputs. To be precise, initially registers and RAM are set to 0, then at each step, the following happen:

• the inputs are read,
• then the netlist is executed, omitting registers and RAM writes (the values to be written in registers and RAM are just stored),
• the RAM is updated,
• the registers are updated,
• the outputs are printed.

Everithing is stored on unsigned 64-bits integers as it is the standard size on modern computers, bus of size 65 or plus are thus not supported. It should not be a problem as the CPU which will be designed shouldn't use too wide buses.

The main difficulty was to understand well the memory model which is different from the way we interact with RAM and ROM on a higher-level.