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：
9 |. D, L& B8 J1 LHigh code coverage雖然是dynamic verification的第一步驟
8 C0 Y2 F8 h" k7 X; R但是通常並不意味著 一定會有 high functional coverage
6 C# W# y# m/ }  m
請問有人可以舉例嗎?
, \  I$ d# V+ }2 x( X' m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
) U, y. v- O( i7 P3 F0 q0 gCoverage 有六大類:
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Line Coverage
Conditional Coverage
FSM Coverage
7 R; G' X. h1 t* t! S4 v( }Toggle Coverage
Branch Coverage
0 O1 s% j0 X* }" xPath Coverage
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有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,
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always @(posedge clk)
begin
      if(A)
& O3 @7 Y+ C* L Q <= #1 D0;
  a; _" z4 v8 Z# h4 j7 \& ^      else if(B)
% C# g" V8 ~$ F; k5 R. E/ n9 S Q <= #1 D1;
end
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0 D+ d1 t9 P3 T( j+ p//======================================//
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  t( q+ j5 D% [) O& C. lalways @(posedge)
Q <= #1 (A)? D0 : (B)? D1 : Q;
" _4 x6 B1 N6 j4 h1 G
The code coverage of second is higher than that of the first.
6 W/ S* b- {: T  Y# O, U+ b+ sThe code coverage is affected by the coding style.
* Q( I1 H- H% B+ Y' wThe more readably code may have a low code coverage.

6 N# s# i* N# X+ uSincrely,
Jarod

kevin

code coverage:看low level design block(state machine,branch,case...)有幾成已被
6 Q# g4 u- m$ [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.
; W$ q" \  B$ b9 |  |- P做Functional Coverage 也要有 functional coverage model.(跟 ic spec.有關)
2 [0 U4 R9 P) q: J3 v舉個例,一個state machine,輸出順序跟 ic spec相反,code coverage 100%, Functional Coverage 0%.