High code coverage does not imply higj functional coverage?

stanlly9

這個論壇似乎沒有 Verification 的Topics
我想請教的是：
High code coverage雖然是dynamic verification的第一步驟
* H2 Q9 Y( u, o) Y' N: g但是通常並不意味著 一定會有 high functional coverage

( H! I- t1 f- Q8 H請問有人可以舉例嗎?
- ]! Q0 q1 c" L( ]什麼例子下
0 Q1 |- V0 I$ P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:

Line Coverage
Conditional Coverage
3 o7 H+ x8 ~- t5 s* F: l- P4 w$ AFSM Coverage
: t2 V# Z0 Q9 H4 o" L: |1 lToggle Coverage
Branch Coverage
Path Coverage

有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,

; z- h9 e1 T* O& r3 F  halways @(posedge clk)
# y3 p* t! b3 d# h, a8 v& m! M% Pbegin
      if(A)
Q <= #1 D0;
      else if(B)
Q <= #1 D1;
end

//======================================//

always @(posedge)
+ U2 k# c# r2 h% ^# K Q <= #1 (A)? D0 : (B)? D1 : Q;

; p0 P7 \; G8 u. Q& e4 {The code coverage of second is higher than that of the first.
The code coverage is affected by the coding style.
* [; W9 a. z9 V% S. X+ `) a- RThe more readably code may have a low code coverage.

- T0 r( X5 X  W+ ~Sincrely,
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.
& h/ {$ `* D1 @2 q- e  ~, ^Functional Coverage: 看design 的 function spec 有幾成已被check過.
) R! P1 N5 M; m0 p) ucode coverage 與 Functional Coverage是互補的.
做Functional Coverage 也要有 functional coverage model.(跟 ic spec.有關)
- l" g- h, J1 F+ u; H+ u0 S* U舉個例,一個state machine,輸出順序跟 ic spec相反,code coverage 100%, Functional Coverage 0%.