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发表于 2016-6-24 11:02:02
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可以参考Verilog标准2005 5.2.1小节:
Several contiguous bits in a vector net, vector reg, integer, or time variable, or parameter can be addressed
and are known as part-selects. There are two types of part-selects, a constant part-select and an indexed partselect.
A constant part-select of a vector reg or net is given with the following syntax:
vect[msb_expr:lsb_expr]
Both msb_expr and lsb_expr shall be constant integer expressions. The first expression has to address a
more significant bit than the second expression
如果想要使用变量,可以使用这种方式:
An indexed part-select of a vector net, vector reg, integer, or time variable, or parameter is given with the
following syntax:
reg [15:0] big_vect;
reg [0:15] little_vect;
big_vect[lsb_base_expr +: width_expr]
little_vect[msb_base_expr +: width_expr]
big_vect[msb_base_expr -: width_expr]
little_vect[lsb_base_expr -: width_expr]
The msb_base_expr and lsb_base_expr shall be integer expressions, and the width_expr shall be a
positive constant integer expression. The lsb_base_expr and msb_base_expr can vary at run time. |
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