- has_channels = [idx for idx in idx_channels if idx is not None]
- if not has_channels:
- raise ChannelError('At least one channel has to be supplied.')
- max_connected = max(has_channels)
+ has_data = [idx for idx in data_indices if idx is not None]
+ if not has_data:
+ raise ChannelError('Need at least one data channel.')
+ max_connected = max(has_data)
+
+ # Pre-determine which input data to strip off, the width of
+ # individual items and multiplexed words, as well as format
+ # strings here. This simplifies call sites which run in tight
+ # loops later.
+ upper_data_bound = max_connected + 1
+ num_item_bits = upper_data_bound - Pin.DATA_0
+ num_word_items = self.options['wordsize']
+ num_word_bits = num_item_bits * num_word_items
+ num_digits = (num_item_bits + 4 - 1) // 4
+ self.fmt_item = "{{:0{}x}}".format(num_digits)
+ num_digits = (num_word_bits + 4 - 1) // 4
+ self.fmt_word = "{{:0{}x}}".format(num_digits)