状态机与数据路径.ppt
6.4.2 状态机与数据路径,数据通道结构,FSMD系统结构,S=S0,S1,S2,Sl表示状态集合；I=i0，i1，i2，,im表示输入集合；O=o0,o1,o2,.,on表示输出集合；V=v0,v1,v2,.,vn表示变量集合；F：SIVS 表示映射某种集合到某一状态的瞬态函数；H：SO+V表示当前状态映射到输出或变量的激活函数；S0是初始状态。,研究目标,1.资源约束:硬件功能单元 如：算数单元(abs,max,min,+,-)移位器2.时间约束:时序约束 如：有限状态机状态数量，流水线结构,时间调度与分配,数据流结构 X=a(axb)+(cxd)+d数据流向图把计算表达式转化为计算路径的方法同步结构：任何时刻只能保存一个数值；异步结构：每条线对应数据队列，数据进出队列与节点的数据处理是异步操作。,数据流,X=a(axb)+(cxd)+d,调度算法(1/7),调度算法(2/7),ASAP（as soon as possible）：假设每一操作要在一个时钟内精确执行。在每一个状态内，功能单元和资源是可变的。执行的操作都是可变的。ALAP(as late as possible)：如果计算路径保持到最终的计算步骤，则操作在最后可能的状态内执行，,ASAP,ALAP（time constraint is 4）,调度算法(3/7),mobility,Scheduling:资源约束One multiplier and two adders,调度算法(4/7),功能单元分配：Multi(*)adder(+1)adder(+2)S_1 op1 op5S_2 op7 op2S_3 op3S_4 op6 op4S_5 op8,资源分配：,调度算法(5/7),寄存器分配(lifetime of each operand),需要 7 registers,调度算法(6/7),Left edge algorithmR1:a,t3,t4 R2:b,t2,t7R3:c,t6 R4:dR5:e R6:t1R7:t5,调度算法(7/7),.,Datapath 优化,1.Resource optimization(a)存储共享(b)功能单元共享(c)总线共享(d)寄存器合并2.Time optimization(a)连接或多循环(b)功能单元 pipelining(c)数据路径 pipelining(d)控制路径 pipelining,连接与多循环操作,连接允许在同一状态中执行两个以上操作的串行执行。连接减少状态数并增加功能。多循环操作允许一个操作在两个以上时钟周期执行操作。多循环操作减小功能单元的尺寸。连接与多循环操作常常被用在非关键路径以提高资源利用率和功能。,交通信号控制器(1/7),Control Unit,Datapath,Counter,Comparator,Red,Green,Yellow,NextState Logic,OutputLogic,State Registers,Seq.,Comb.,Comb.,Recount_counter,R,Y,G,1/100,1/010,1/001,0/100,0/010,0/001,Recount_Counter16/Red Green Yellow,Input/Output,Rt Gt Yt,Current_times,Recount_counter,4 2 0,R_time:4+1=5 cycles G_time:2+1=3 cycles Y_time:0+1=1 cycles,Traffic Light Controller(2/7),module traffic(Clock,Reset,Red,Green,Yellow);input Clock,Reset;output Red,Green,Yellow;wire Recount_conter;wire 3:0 Counter_Number;Traffic_Control(.Clock(Clock),.Reset(Reset),.Recount_Counter16(Recount_conter),.Red(Red),.Green(Green),.Yellow(Yellow);Datapath(.Clock(Clock),.Reset(Reset),.RGY(Red,Green,Yellow),.Recount(Recount_conter);endmodule,module Datapath(Clock,Reset,RGY,Recount);input Clock,Reset;input 2:0 RGY;output Recount;wire 3:0 Counter_Number;Compare A1(.current_times(Counter_Number),.RGY(RGY),.Recount_conter16(Recount);Counter16 A2(.Clock(Clock),.Reset(Reset),.Recount_Counter16(Recount),.Count_Out(Counter_Number);endmodule,Traffic Light Controller(3/7),module Counter16(Clock,Reset,Recount_Counter16,Count_Out);input Clock,Reset,Recount_Counter16;output 3:0 Count_Out;reg 3:0 Count_Out;always(posedge Clock)begin if(Reset)Count_Out=0;else begin if(Recount_Counter16)Count_Out=0;else Count_Out=Count_Out+1;endendendmodule,Traffic Light Controller(4/7),module compare(current_times,RGY,Recount_conter16);input 2:0 RGY;input 3:0 current_times;output Recount_conter16;reg Recount_conter16;parameter R_times=4,G_times=2,Y_times=0;always(RGY)begin case(RGY)3b100:beginif(current_times=R_times)Recount_conter16=1;else Recount_conter16=0;end,3b001:begin if(current_times=Y_times)Recount_conter16=1;else Recount_conter16=0;end 3b010:begin if(current_times=G_times)Recount_conter16=1;else Recount_conter16=0;end default:Recount_conter16=1;endcaseendendmodule,Traffic Light Controller(5/7),State Register(Seq.C.),Next State Logic(Comb.C.),module Traffic_Control(Clock,Reset,Recount_Counter16,Red,Green,Yellow);input Clock,Reset,Recount_Counter16;output Red,Green,Yellow;reg Red,Green,Yellow;reg 1:0currentstate,nextstate;parameter 1:0 Red_Light=0,Green_Light=1,Yellow_Light=2;always(posedge Clock)begin if(Reset)currentstate=Red_Light;else currentstate=nextstate;end,always(currentstate)begin case(currentstate)Red_Light:beginif(Recount_Counter16)nextstate=Green_Light;else nextstate=Red_Light;end Green_Light:beginif(Recount_Counter16)nextstate=Yellow_Light;else nextstate=Green_Light;end Yellow_Light:beginif(Recount_Counter16)nextstate=Red_Light;else nextstate=Yellow_Light;end default:nextstate=Red_Light;endcaseend,Traffic Light Controller(6/7),Output Logic(Comb.C.),always(currentstate)begin case(currentstate)Red_Light:beginRed=1b1;Green=1b0;Yellow=1b0;end Green_Light:beginRed=1b0;Green=1b1;Yellow=1b0;end Yellow_Light:beginRed=1b0;Green=1b0;Yellow=1b1;end,default:beginRed=1b0;Green=1b0;Yellow=1b0;endendcaseendendmodule,Traffic Light Controller(7/7),R_time:4+1=5 cycles G_time:2+1=3 cycles Y_time:0+1=1 cycles,R,Y,G,1/010,1/001,0/100,0/010,0/001,Recount_Counter16/Red Green Yellow,Input/Output,Homework:Design traffic controller with Mealy machine,1/100,
