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
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* s; I! m6 f2 R1 f1 Q4 b( ]0 y2 C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
; {) F; ?8 x( V; D; q! w[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:
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Line Coverage
$ O7 A+ z1 v2 P; ^/ l6 a/ {% cConditional Coverage
/ d  @/ x: w# z5 OFSM Coverage
Toggle Coverage
Branch Coverage
Path Coverage
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8 N/ v7 ?: x1 x6 M/ O0 i有誰能說明這幾種 Coverage 的定義呢?

jarodz

For example,

always @(posedge clk)
4 [' T; S) e3 {/ r4 M4 U2 sbegin
      if(A)
Q <= #1 D0;
" A9 S( ]! M' M- N3 x7 l% x      else if(B)
Q <= #1 D1;
end
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+ p- @7 D( e6 [- L7 c//======================================//

* x; ]: F, X0 o3 a; malways @(posedge)
Q <= #1 (A)? D0 : (B)? D1 : Q;
1 D9 Y( n5 d1 B, _4 \
! \0 i: d' Z& ?2 NThe code coverage of second is higher than that of the first.
The code coverage is affected by the coding style.
The more readably code may have a low code coverage.

( U% Q7 x8 ^" b1 N. l& t4 h7 xSincrely,
Jarod

kevin

code coverage:看low level design block(state machine,branch,case...)有幾成已被
: I) Z$ M/ `  r2 Trun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.
; \! Y3 z0 X! ^6 a0 ~8 f) K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%.