需要概念来理解系统 verilog 中的数组声明 [英] need concept to understand declaration of array in system verilog

问题描述

在 SystemVerilog 中声明数组和数组查询函数时，我总是感到困惑.你能详细解释一下给定的例子吗:

I am always confusing while declaring an array and Array Querying Function in SystemVerilog. Can you explain me in details for given example:

示例 1

integer matrix[7:0][0:31][15:0];

// 3-dimensional unpacked array of integers i am confuse in size 
// and dimension of given array for 1 and 2 dimension its easy to 
// understand but for 3 and 4-dimension its little bit confusing...

示例 2

//bit [1:5][10:16] foo [21:27][31:38]; 

示例 3

//module array(); 

bit [1:5][10:16] foo1 [21:27][31:38],foo2 [31:27][33:38]; 

initial 

begin 

$display(" dimensions of foo1 is %d foo2 is %d",$dimensions(foo1),$dimensions(foo2) );

end 

输出...

dimensions of foo1 is 4 foo2 is 4

我也没有得到这个...

I am not getting this also...

推荐答案

参见 Sec: 7.4.5 Multidimensional arrays of IEEE 1800-2009

See Sec: 7.4.5 Multidimensional arrays of IEEE 1800-2009

标识符前面的维度设置打包维度.标识符后面的维度设置解包维度.

The dimensions preceding the identifier set the packed dimensions. The dimensions following the identifier set the unpacked dimensions.

bit [3:0] [7:0] joe [1:10]; // 10 elements of 4 8-bit bytes 

在多维声明中，在类型之后和名称之前声明的维度(前面声明中的[3:0][7:0])比名称后面的维度变化更快([1:10] 在前面的声明中).引用时，压缩尺寸 ([3:0], [7:0]) 遵循解包尺寸 ([1:10]).

In a multidimensional declaration, the dimensions declared following the type and before the name ([3:0][7:0] in the preceding declaration) vary more rapidly than the dimensions following the name ([1:10] in the preceding declaration). When referenced, the packed dimensions ([3:0], [7:0]) follow the unpacked dimensions ([1:10]).

即在维度列表中，最右边的变化最快，如在 C 中.但是，打包维度的变化比未打包维度变化得更快.

i.e. In a list of dimensions, the rightmost one varies most rapidly, as in C. However, a packed dimension varies more rapidly than an unpacked one.

bit [1:10] v1 [1:5]; // 1 to 10 varies most rapidly
bit v2 [1:5] [1:10]; // 1 to 10 varies most rapidly
bit [1:5] [1:10] v3 ; // 1 to 10 varies most rapidly
bit [1:5] [1:6] v4 [1:7] [1:8]; // 1 to 6 varies most rapidly, followed by 1 to 5, then 1 to 8 and then 1 to 7

示例 1:您可以这样查看设置:

示例 2:

bit [1:5][10:16] foo [21:27][31:38];

这与示例 1 类似.

示例 3:

module array(); 

bit [1:5][10:16] foo1 [21:27][31:38],foo2 [31:27][33:38]; 

initial 

begin 

$display(" dimensions of foo1 is %d foo2 is %d",$dimensions(foo1),$dimensions(foo2) );

end 

上述模块中的声明同

bit [1:5][10:16] foo1 [21:27][31:38];
bit [1:5][10:16] foo2 [31:27][33:38];

正如 Dave 所提到的，$dimensions 函数为您提供了打包和解包的维度总数.因为 foo1 和 foo2 都是 4 维的，所以显示的值为 4.

As Dave has mentioned, $dimensions function gives you the total number of dimensions packed and unpacked. Sice both foo1 and foo2 are 4 dimensional the displayed value is 4.

有关此主题的更多信息，请访问以下链接.这将消除你所有的疑虑.这里提供了一个很好的表示.http://testbench.in/SV_09_ARRAYS.html

For more on this topic please go though the following link. This would clear your all doubts. A nice representation is provided here. http://testbench.in/SV_09_ARRAYS.html

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