Question

计算机操作系统第三版第二章，求22题，试写出相应的程序来描述图2-17所示的前趋图的图

Answer 1

var a, b, c, d, e, f, g, h, i, j: semaphore: =0,0,0,0,0,0,0,0,0,0;

begin S1; signal(a); signal(b); end;

begin wait(a); S2; signal(c); signal(d); end;

begin wait(b); S3; signal(e); signal(f); end;

begin wait(c); S4; signal(g); end;

begin wait(d); S5; signal(h); end;

begin wait(e); S6; signal(i); end;

begin wait(f); S7; signal(j); end;

begin wait(g); wait(h); wait(i); wait(j); S8; end;

 

如果不是这图，类似的 也可以自己敲