verilog 觸發的問題

scroll529

請問....
" K! r7 }  l' }! ~. V* C! z    always (*)
, z! C2 L" R% E  t% L     begin
. y3 u( p9 l; r& E      if(!rstn) r1 = r2 + r3 ;
      else      r1 = r5 << 4;
     end
. W) k8 H8 i) y& E  w    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
   
     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，
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

( N7 ^/ W, f1 F( Jalways @(*)
     begin
3 Q! U; k' t3 K$ ^7 ]* g& Z' ]      if(!rstn) r1 = r2 + r3 ;
& x: i7 z& {  y5 n4 Y2 ?$ z      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
was to create concise, error-free combinational always blocks. The @* basically means, "if Synopsys DC wants the
' i. k  a6 a3 b8 U. Z. H6 n+ wcombinational signal in the sensitivity list, so do we!"
Example 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.
6 C6 s. e# {  J  N' X# _
* z1 _' I5 ]6 `, s) falways @(state or go or ws)
* g! S1 B9 `0 L( U+ Obegin
0 X5 r. M* h4 Y  K0 K...
9 a( F; {  b2 q# S! _, Y7 z9 vend
; A5 ~0 {5 w/ Q8 o8 B; u' L' D//Example 1
5 c6 M" {6 ~$ O
  C1 e1 u& \) q' B: u
always @*
begin
( @$ l# {2 k3 |0 Z...
end
//Example 2

4 x, H4 c2 _+ S5 AThe @* combinational sensitivity list as defined in the IEEE Verilog-2001 Standard can be written with or without
2 N3 ~4 b) N2 f/ C: e$ |) T) rparentheses and with or without spaces as shown in Example 3. Unfortunately (* is the token that is used to open
7 K* ?- D# T7 P8 Q! Q! M8 L! Va Verilog-2001 attribute, so there is some debate about removing support for all but the always @* form of this
5 K3 m5 E/ c$ ocombinational 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.
always @*
always @ *
, }% ?; r+ x& h7 halways @(*)
always @ ( * )
//Example 3