AR# 2213: M1.x EPIC - How do I read the CLB carry mode?
M1.x EPIC - How do I read the CLB carry mode?
Keywords: carry logic, EPIC
General Description: How do I determine a CLB's carry mode in EPIC?
Select the CLB in EPIC, then click "Editblock". In the Editblock screen, select "Carry". The CLB carry mode will be highlighted in the list of possible carry modes.
You can also determine the carry mode directly from the CLB diagram in Editblock:
1. The carry function type (e.g., ADD or ADDSUB) is selected from the list in the in the CARRYMODE entity.
2. The function generators used by the carry mode (F, G, or FG) have the CARRY check box filled in.
3. The carry source (e.g., 0, 1, or CI) is indicated by the corresponding selected input on the 6-to-1 carry mux.
In the example Editblock screen below, the ADDSUB function is selected (1), both F and G carry blocks are active (2), and the CI input is active on the carry mux (3). This indicates that the carry mode is ADDSUB-FG-CI.