handshaking_busy.txt

# To add a busy into AXI
# handshaking, you AND the upstream READY !BUSY, and AND the
# downstream valid with !BUSY

>>> ready_prev = []
>>> for ready in range(2):
...  for busy in range(2):
...   ready_prev.append(
	{"ready_prev": ready & ~busy, "ready": ready, "busy": busy}
)
... 
>>> for item in ready_prev:
...  print(item)
...
{'ready_prev': 0, 'ready': 0, 'busy': 0}
{'ready_prev': 0, 'ready': 0, 'busy': 1}
{'ready_prev': 1, 'ready': 1, 'busy': 0}
{'ready_prev': 0, 'ready': 1, 'busy': 1}

>>> valid_next = []
>>> for valid in range(2):
...  for busy in range(2):
...   valid_next.append(
	{"valid_next": valid & ~busy, "valid": valid, "busy": busy}
)
... 
>>> for item in valid_next:
...  print(item)
...
{'valid_next': 0, 'valid': 0, 'busy': 0}
{'valid_next': 0, 'valid': 0, 'busy': 1}
{'valid_next': 1, 'valid': 1, 'busy': 0}
{'valid_next': 0, 'valid': 1, 'busy': 1}

# Old stuff, not working:
#>>> ready_prev = []
#>>> for ready in range(2):
#...  for busy in range(2):
#...   ready_prev.append(
#	{"ready_prev": ready | busy, "ready": ready, "busy": busy}
#)
#... 
#>>> for item in ready_prev:
#...  print(item)
#... 
#{'ready_prev': 0, 'ready': 0, 'busy': 0}
#{'ready_prev': 1, 'ready': 0, 'busy': 1}
#{'ready_prev': 1, 'ready': 1, 'busy': 0}
#{'ready_prev': 1, 'ready': 1, 'busy': 1}