From: Steven Sharp (sharp@cadence.com)
Date: Tue Jul 20 1999 - 11:06:14 PDT
The IEEE 1364-1995 standard states in section 4.1.12 that the right operand
of a shift is always treated as an unsigned number.
Verilog-XL handles negative signed shift counts by shifting the opposite
direction by the absolute value of the shift count.
This is clearly a difference between the standard and the behavior of XL.
The XL manual does not document this situation at all. It could be considered
an error in the standard or non-compliance by XL.
For what it is worth, this is one situation where we decided to make
NC-Verilog match the IEEE standard instead of XL. We may have had a bug
report because of it, since I remember being aware of the difference. It
has not been a significant issue with any customers.
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