Primitives
XST supports certain gate level primitives. The supported syntax is as follows:
gate_type instance_name (output, inputs, ...);
The following example shows Gate Level Primitive Instantiations.
and U1 (out, in1, in2);
bufif1 U2 (triout, data, trienable);
The following table shows which primitives are supported.
Table 7-10 Primitives
|
Gate Level Primitives
|
and nand nor or xnor xor |
Supported |
| buf not |
Supported |
| bufif0 bufif1 notif0 notif1 |
Supported |
| pulldown pullup |
Unsupported |
| drive strength |
Ignored |
| delay |
Ignored |
| array of primitives |
Unsupported |
|
Switch Level Primitives
|
cmos nmos pmos rcmos rnmos rpmos |
Unsupported |
| rtran rtranif0 rtranif1 tran tranif0 tranif1 |
Unsupported |
| User Defined Primitives |
|
Unsupported |