AR# 7561: CPLD XPLA Professional - What does the attribute "ISTYPE INVERT" do?
AR# 7561
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CPLD XPLA Professional - What does the attribute "ISTYPE INVERT" do?
Description
Keywords: XPLA Professional, CoolRunner, fitter, attribute, ISTYPE, INVERT, PHDL, ABEL
Urgency: Standard
General Description: What does the attribute "ISTYPE INVERT" do?
Solution
This attribute only has meaning for registered signals; it has no meaning for combinatorial equations. The software will remove this attribute for combinatorial equations at the first stage of normalization before any further processing.
ISTYPE INVERT means that there is an inverter between the macrocell register and the output buffer. If the user specifies ISTYPE INVERT for 22v10 devices, the software keeps the inverter. However, since XPLA devices do not have an inverter between the macrocell register and the output buffer, this will be emulated.