1. A computer-readable memory medium configured to store program instructions, wherein the program instructions are executable to implement: receiving first user input selecting a first graphical primitive having an output terminal, wherein the first graphical primitive represents a first circuit entity that provides a first digital timing signal at the output terminal; generating first program code for the first graphical primitive, wherein the first program code is configured as a first loop which writes values of the first digital timing signal to a first variable corresponding to the output terminal; receiving second user input selecting a second graphical primitive having an input terminal, wherein the second graphical primitive represents a second circuit entity that receives a second digital timing signal; generating second program code for the second graphical primitive, wherein the second program code is configured as a second loop; receiving third user input connecting the output terminal of the first graphical primitive to the input terminal of the second graphical primitive with a first wire that does not impose a dataflow ordering dependency between the first program code and the second program code; updating the second program code, in response to receiving said third user input, so that the second loop is configured to read the second digital timing signal from the first variable, wherein the second loop is configured to iterate independently of the first loop; storing a program including the first program code and the second program code in a memory medium.