verilog - 为什么 Verilog 函数中不允许非阻塞赋值？

Question

我读过 Verilog 函数中不允许使用非阻塞赋值。任何人都可以对此提出合理的解释吗？

Answer 1

Verilog 的 IEEE 标准 (1364-2001)，“10.3.4 函数规则”部分指出:

A function shall not have any nonblocking assignments.

1800-2009 IEEE Std 对此进行了详细说明:

Functions shall execute with no delay. Thus, a process calling a function shall return immediately. Statements that do not block shall be allowed inside a function; specifically, nonblocking assignments, event triggers, clocking drives, and fork-join_none constructs shall be allowed inside a function.

目的是让函数在 Verilog 事件队列中易于评估。如果您需要提前时间，请使用 task而不是 function .