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
但是通常並不意味著 一定會有 high functional coverage

3 W) C7 L0 Y7 J2 ?0 B$ T+ `請問有人可以舉例嗎?
什麼例子下
會有 high code coverage 但是 functional coverage 卻不高
" S# K1 C; I4 R; p* P[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:
0 j; N0 {  V$ P1 s" r, `
# o% |4 i5 m8 L" ILine Coverage
Conditional Coverage
FSM Coverage
0 `1 R; D* ?2 O$ TToggle Coverage
Branch Coverage
Path Coverage

有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,
3 h4 }, Z) O3 u# B2 B! v. n, \" y
) \% j: ~& M' ?0 Balways @(posedge clk)
begin
4 g& \5 J! X7 n7 F6 N) L" S      if(A)
Q <= #1 D0;
      else if(B)
: b- |4 P  w1 @. y2 h* h. k Q <= #1 D1;
3 t8 |8 Q7 w( `4 A( h& j) n1 {end
% \$ t$ P" ]. Y/ r
//======================================//

always @(posedge)
Q <= #1 (A)? D0 : (B)? D1 : Q;

The code coverage of second is higher than that of the first.
4 r, W3 i% B+ h( c# LThe code coverage is affected by the coding style.
The more readably code may have a low code coverage.

* N; J0 f/ `  v/ ?Sincrely,
  ]. M( }; z3 h: OJarod

kevin

code coverage:看low level design block(state machine,branch,case...)有幾成已被
" m0 `; _1 d# V! f+ i) z2 Qrun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.
1 @) F2 }) T7 Y9 acode coverage 與 Functional Coverage是互補的.
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%.