Answers Database
XPLA Professional: Attribute ISTYPE INVERT.
Record #7561
Product Family: Software
Product Line: CoolRunner
Product Part: XPLA Fitter
Problem Title:
XPLA Professional: Attribute ISTYPE INVERT.
Problem Description:
Urgency: Standard
General Description: What does the attribute ISTYPE INVERT do?
Solution 1:
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.
EXAMPLE (please note the spacing):
Source code:
O1 pin istype 'reg, invert';
O2, O3 pin istype 'com';
AR, CLK, IN pin;
O1.d = IN;
O1.AR = AR;
O1.CLK = CLK;
O2 = O1.Q;
O3 = O1.FB;
Resulting Equations for XPLA Devices:
!O1.d = IN; " Inversion occurs at the D input
O1.AP = AR; " note that AP is now used
O1.CLK = CLK;
O2 = !O1.q; " Inversion of the Q output occurs to negate the inversion
"at the D input
O3 = !O1.q;
Resulting Equations for 22V10 Devices:
O1.d = IN;
O1.AR = AR;
O1.CLK = CLK;
O2 = O1.q;
O3 = O1.q;
End of Record #7561 - Last Modified: 10/11/99 16:55 |
