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
  k8 {7 n* @" e- A0 Y$ E5 w但是通常並不意味著 一定會有 high functional coverage

請問有人可以舉例嗎?
8 @3 r4 M' W! E& a# E什麼例子下
, D% |6 W5 b8 Y: G$ S( ]6 A6 \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
6 z. K8 a8 ?9 E0 B) s- A9 WCoverage 有六大類:
# z- m) b) |8 ?
+ r) u  J: q8 dLine Coverage
. Y- c/ S9 f6 @+ ~+ z7 IConditional Coverage
FSM Coverage
/ z/ M* ]  M2 e! PToggle Coverage
, w- I# g  H9 M" {Branch Coverage
( ]2 m3 F" x. n/ h- d: QPath Coverage
$ @) K, q, u! p  r" v: B$ n
有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,
# v7 I" n, v' J4 _) G2 O
always @(posedge clk)
& w2 Q$ E8 V  I" r8 \; _begin
/ y2 g9 G( h* C      if(A)
Q <= #1 D0;
      else if(B)
0 p/ j/ A5 o2 Q- ]5 W) b. O  E# H Q <= #1 D1;
9 ?. n+ x  i4 u8 Tend

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

always @(posedge)
1 q* \0 w; o/ M2 D3 e& a Q <= #1 (A)? D0 : (B)? D1 : Q;

The code coverage of second is higher than that of the first.
( P$ e5 o4 s! U- o* LThe code coverage is affected by the coding style.
The more readably code may have a low code coverage.
; K8 ]- V/ Y  s3 S4 ]$ z  {* e
! w8 D; b( A8 r# E# V5 Z  A9 HSincrely,
Jarod

kevin

code coverage:看low level design block(state machine,branch,case...)有幾成已被
! b( q7 P& N6 V4 g/ Frun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.
2 d7 M, q* @' I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%.