英文:
Explicit assignment pattern type
问题
I'd like to be able to provide an explicit struct type in an assignment pattern (1800-2012 sec. 10.9) so that the left-hand side of the assignment does not need to be of that struct type. Is there a way to accomplish this?
例如，我想要做类似以下的事情：
logic a, b;
logic [1:0] c;
assign c = struct_t'{s1:a, s2:b};```
另一种方法是：
```typedef struct packed { logic s1; logic s2 } struct_t;
logic a, b;
struct_t tmp;
logic [1:0] c;
always_comb begin
tmp = '{s1:a, s2:b};
c = tmp;
end
但是这显然有一个缺点，需要一个临时变量。
在标准中，我没有看到类似这样的内容。此外，我尝试在 QuestaSim 中使用它，但它不起作用，尽管它也没有抱怨表达式 struct_t'{s1:a, s2:b}; 的语法错误。根据赋值模式的语法表，这似乎是无效的语法。对吗？
有没有办法实现我想要的效果？我还尝试了将赋值模式进行类型转换，如 struct_t'('{s1:a, s2:b})，但也没有成功。
英文:
I'd like to be able to provide an explicit struct type in an assignment pattern (1800-2012 sec. 10.9) so that the left-hand side of the assignment does not need to be of that struct type. Is there a way to accomplish this?
For example, I'd like to do something like the following:
typedef struct packed { logic s1; logic s2 } struct_t;
logic a, b;
logic [1:0] c;
assign c = struct_t'{s1:a, s2:b};
An alternative would be to do:
typedef struct packed { logic s1; logic s2 } struct_t;
logic a, b;
struct_t tmp;
logic [1:0] c;
always_comb begin
tmp = '{s1:a, s2:b};
c = tmp;
end
But that has the obvious disadvantage of requiring a temporary variable.
I didn't see any mention of something like this in the standard. Additionally, I tried it with QuestaSim and it didn't work, though it also didn't complain about a syntax error with the expression struct_t'{s1:a, s2:b};. Based on the syntax table for assignment patterns, this appears to be invalid syntax. Is that right?
Is there some way to achieve what I want? I also tried to cast the assignment pattern, like struct_t'('{s1:a, s2:b}), but that didn't work either.
答案1
得分: 0
以下是您要翻译的内容：
"Since these are all packed types, they should all be assignment compatible.
I get a syntax error in your typedef - missing a semicolon after s2
** Error: (vlog-13069) myfile.sv(3): near "}": syntax error, unexpected '}', expecting ';' or ','.
Once I fix that, it works for me. If you don't agree please show a complete example with the actual errors."
英文:
Since these are all packed types, they should all be assignment compatible.
I get a syntax error in your typedef - missing a semicolon after s2
** Error: (vlog-13069) myfile.sv(3): near "}": syntax error, unexpected '}', expecting ';' or ','.
Once I fix that, it works for me. If you don't agree please show a complete example with the actual errors.
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