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Xilinx Synthesis Technology User Guide

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XST <strong>User</strong> <strong>Guide</strong><br />

Operators<br />

Operands<br />

Note XST does not allow underscores as the first character of signal<br />

names (for example, _DATA_1).<br />

Table 6-7 Expressions<br />

Logical Operators:<br />

and, or, nand, nor, xor, xnor, not<br />

Supported<br />

Relational Operators:<br />

=, /=, =<br />

Supported<br />

& (concatenation) Supported<br />

Adding Operators: +, - Supported<br />

* Supported<br />

/, mod, rem Supported if the right operand is a<br />

constant power of 2<br />

Shift Operators:<br />

sll, srl, sla, sra, rol, ror<br />

Supported<br />

abs Supported<br />

** Only supported if the left operand is 2<br />

Sign: +, - Supported<br />

Abstract Literals Only integer literals are supported<br />

Physical Literals Ignored<br />

Enumeration Literals Supported<br />

String Literals Supported<br />

Bit String Literals Supported<br />

Record Aggregates Supported<br />

Array Aggregates Supported<br />

Function Call Supported<br />

Qualified Expressions Supported for accepted predefined<br />

attributes<br />

Types Conversions Supported<br />

Allocators Unsupported<br />

Static Expressions Supported<br />

6-44 <strong>Xilinx</strong> Development System

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