High code coverage does not imply higj functional coverage?

stanlly9

這個論壇似乎沒有 Verification 的Topics
& D) ?, P" l7 I/ J我想請教的是：
High code coverage雖然是dynamic verification的第一步驟
' o* b4 c1 |3 c- W% E但是通常並不意味著 一定會有 high functional coverage
2 @/ H9 @: j- D
請問有人可以舉例嗎?
什麼例子下
9 v5 V6 D* {* w7 c# a% O$ @. B會有 high code coverage 但是 functional coverage 卻不高
[聽說 functional coverage的界定不是很明確...請以自己的想法回答即可

masonchung

一般而言
Coverage 有六大類:

$ {$ [/ f6 s9 K+ _$ q7 BLine Coverage
  ]$ X( o* F* t1 f0 N2 s" @  [: V  @Conditional Coverage
FSM Coverage
Toggle Coverage
6 C1 |+ `5 y  ?Branch Coverage
$ L! X3 K8 K3 i+ v. uPath Coverage

有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,

always @(posedge clk)
begin
      if(A)
Q <= #1 D0;
' J4 c4 E; `; m3 r4 O4 V      else if(B)
Q <= #1 D1;
( M  }! _( V* C, s: S& kend
5 I' i: W# |( h, L! I( w3 F
//======================================//

6 B. V1 ^3 ?+ ~# f2 I! malways @(posedge)
* H! q: c7 P1 { Q <= #1 (A)? D0 : (B)? D1 : Q;

The code coverage of second is higher than that of the first.
The code coverage is affected by the coding style.
The more readably code may have a low code coverage.

: f$ j  y9 U+ Z% U% I" mSincrely,
Jarod

kevin

code coverage:看low level design block(state machine,branch,case...)有幾成已被
run過.不代表function皆work,且符合spec.
Functional Coverage: 看design 的 function spec 有幾成已被check過.
code coverage 與 Functional Coverage是互補的.
/ U# m+ R) b1 f( l8 `* u做Functional Coverage 也要有 functional coverage model.(跟 ic spec.有關)
舉個例,一個state machine,輸出順序跟 ic spec相反,code coverage 100%, Functional Coverage 0%.