//-----SDA 数据线上的数据存入寄存器，数据在SCL的高电平有效-------------
task shift_in;
 output [7:0] shift;
  begin
     @ (posedge  scl) shift[7] = sda; 
     @ (posedge  scl) shift[6] = sda;
     @ (posedge  scl) shift[5] = sda;
     @ (posedge  scl) shift[4] = sda;
     @ (posedge  scl) shift[3] = sda;
     @ (posedge  scl) shift[2] = sda;
     @ (posedge  scl) shift[1] = sda;
     @ (posedge  scl) shift[0] = sda;
     @ (negedge scl)     
       begin  
         #`timeslice ;
        out_flag = 1;     //应答信号输出
          sda_buf  = 0; 
       end
     @(negedge scl)  
        #`timeslice out_flag  = 0; 
  end
endtask

 @ (negedge scl) 在任务里面怎么用，编译的时候出现错误

eeprom.v" line 140: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 141: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 142: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 143: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 144: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 145: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 146: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 147: Unsupported Event Control Statement.
ERROR:Xst:850 - "eeprom.v" line 148: Unsupported Event Control Statement.
那位老兄帮帮忙啊？谢谢，这是夏宇闻书里I2C总线那章的一个例子？

随便问一下 系统函数DISABLE怎么也不可以用啊？