To simulate with GHDL:
cd ghdl make test
The terminal output should look something like this:
BEGIN: joy0 INFO RGA: power-on sysfreq: 3571 KHz period: 280000000 fs --- simulation begin INFO RGA: power-up reset done DEBUG RGA: write $03C <- $CAFE DEBUG RGA: write $08E <- $2C81 DEBUG RGA: write $090 <- $F4C1 DEBUG RGA: write $100 <- $2000 DEBUG RGA: write $102 <- $0022 DEBUG RGA: read $00A -> $XXXX DEBUG RGA: write $036 <- $55AA DEBUG RGA: read $00A -> $56AA --- simulation end END: joy0
This test case writes to the Denise joystick-mouse
counters via the JOYTEST register ($036) and then reads the
JOY0DAT register ($00A), checking that the writable bits
are updated.
The GHDL testbenches write signal transitions to .ghw files
which can be displayed in the GTKWave waveform viewer.