verilog 觸發的問題

scroll529

請問....
% P4 [4 I) Z8 r3 J( v8 q/ H) ]# R    always (*)
     begin
5 S+ y. ?4 t8 @" L' o4 u      if(!rstn) r1 = r2 + r3 ;
# O& \9 p- A  R: G9 K) M+ B+ {      else      r1 = r5 << 4;
     end
/ n' s2 v5 D4 Q4 `    請問*是表示r2.r3.r5的意思嗎,如果是像這樣子的寫法是否能夠合成
! S& Y) z$ G6 ]* B- {& g! }0 I   
     小弟才疏學淺...謝謝各位大大

newwalkman

敏感表中不仅是要传送的值(r2,r3,r5),还包括判断条件(rstn)

spring69393

敏感列是只要那個變數有變化，就重新判斷一次， * 應該是沒有效果才對，
: u5 }" M! W5 Y1 q( Q; {& m9 u你這樣寫法應該會造成出來的值是跟你所要的不同結果。

videochip

可以合成 !!
不過應該是這樣吧

' i  l; F* }. j5 P2 `always @(*)
     begin
& a% l1 X/ l6 |6 L$ v      if(!rstn) r1 = r2 + r3 ;
/ l3 `  [( m$ s* d7 R5 K; P$ o! Q3 m      else      r1 = r5 << 4;
     end

masonchung

這個是 verilog 2001 的語法喔

賈斯丁

Verilog-2001 added the much acclaimed @* combinational sensitivity list. The primary intent of this enhancement
6 \4 p! o- w- F9 b+ H) a5 Zwas to create concise, error-free combinational always blocks. The @* basically means, "if Synopsys DC wants the
9 H% @# q$ ^- W. s! H" l- v2 c3 Ocombinational signal in the sensitivity list, so do we!"
% `& v  ]: [, O$ `, xExample 1 and Example 2 show the Verilog-1995 and Verilog-2001 versions respectively of combinational
sensitivity lists for the combinational always block of any of the three always block fsm1 coding styles.
$ |! R1 F: D8 T, Z% Q
always @(state or go or ws)
* \2 M* e. Q. Nbegin
9 J! p/ r! x8 {9 c- `+ S- \...
end
//Example 1
' g9 g  `; D% g- |% \
6 c4 U) f: ~- @
" Y% W" M; C5 A* a( z/ N* Balways @*
begin
...
- V0 f0 K# X+ ^4 K6 \end
1 ~; r& t! e: p6 U3 O//Example 2

, z- t& i0 U3 _* @The @* combinational sensitivity list as defined in the IEEE Verilog-2001 Standard can be written with or without
parentheses and with or without spaces as shown in Example 3. Unfortunately (* is the token that is used to open
; l  E' ^* D+ o5 T* t; }a Verilog-2001 attribute, so there is some debate about removing support for all but the always @* form of this
combinational sensitivity list. In-house tools would probably also be easier to write if the in-house tools did not
have to parse anything but the most concise @* form. For these reasons, I recommend that users restrict their usage
of the combinational sensitivity list to the @* form.
  p1 _& f: c2 |6 e& `always @*
always @ *
" Y/ @* y; H* H7 l8 Q& calways @(*)
always @ ( * )
//Example 3