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AR# 10859

4.1i XST - XST does not support "predefined attribute" VHDL expressions.

描述

Keywords: attribute, predefined, VHDL, XST

Urgency: Standard

General Description:
In VHDL, predefined attributes can be useful when you are managing arrays. A small list of these attributes (not comprehensive) follows:

X'left(N)
X'right(N)
X'range(N)
X'length(N)

where "X" refers to the array type or object (commonly a signal) and "N" refers to a number from 1 to the size of the array "X". If no "N" is mentioned, the default is assumed to be the maximum size of "X."

These predefined arrays are not supported in 4.1i XST. (Support for predefined arrays was added in the 5.1i software release.)

解决方案

There is no VHDL code mentioned here because predefined attributes may be used in a variety of ways. You can work around this limit by being explicit, either using generics or by passing the actual value.

The predefined attributes listed above are supported in the 5.1i XST release.
AR# 10859
日期 08/06/2003
状态 Archive
Type 综合文章
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