High code coverage does not imply higj functional coverage?

stanlly9

這個論壇似乎沒有 Verification 的Topics
' a0 @( J* X" ?/ J* i我想請教的是：
High code coverage雖然是dynamic verification的第一步驟
2 F% j9 ?. D' g1 S' X$ N1 J但是通常並不意味著 一定會有 high functional coverage
) }/ c  N6 Q1 j2 N3 i% y6 y2 p
請問有人可以舉例嗎?
2 m2 L3 z, E; C2 U: S" y. T什麼例子下
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:
: M( H8 k6 I- ^) \% n0 s
Line Coverage
) c* h3 |! E2 t" tConditional Coverage
FSM Coverage
+ j; v" _; v5 w" l+ @$ A7 W7 p6 ^Toggle Coverage
Branch Coverage
Path Coverage
! e4 J. F& t5 X( w* {
有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,

& i6 H7 ?& s' ?  n: Walways @(posedge clk)
6 e, W) D5 m0 o- s; r% I0 B- Sbegin
" e5 S$ R3 x0 f      if(A)
8 e9 {1 }3 [9 n: d/ }% O! b$ T Q <= #1 D0;
      else if(B)
Q <= #1 D1;
end
( ]1 J, d6 P- j6 n) ]$ b
0 B9 g/ A$ W) L: h% Y: ^% C//======================================//

2 t, ~# o3 s, n2 [* ~$ e2 Walways @(posedge)
* Q  c& {5 e0 C' M5 s" K. E  U Q <= #1 (A)? D0 : (B)? D1 : Q;
/ l# b' [# j, B
The code coverage of second is higher than that of the first.
6 g9 M9 k+ b# X& x; tThe code coverage is affected by the coding style.
6 W3 W: j, R. K* b# V4 `The more readably code may have a low code coverage.
) g2 h/ v) E9 J) u1 @8 l( i
Sincrely,
: v: t3 J4 o4 u% y6 [7 s2 l7 W& E6 i: JJarod

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.
做Functional Coverage 也要有 functional coverage model.(跟 ic spec.有關)
% m/ @" e1 ?2 k! L. `# b0 k) v舉個例,一個state machine,輸出順序跟 ic spec相反,code coverage 100%, Functional Coverage 0%.