zcy
/
tinyriscv
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

rtl: rib: arbitrated by logic instead of clock 

Signed-off-by: liangkangnan <liangkangnan@163.com>
pull/1/head
Blue Liang 2020-08-13 08:56:01 +08:00
parent 4b5904df81
commit fa958a6153
1 changed files with 15 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
rtl/core/rib.v
View File

@ -122,103 +122,38 @@ module rib(
parameter [1:0]grant2 = 2'h2;
parameter [1:0]grant3 = 2'h3;
wire[3:0] req;
reg[1:0] grant;
reg[1:0] next_grant;
// 主设备请求信号
assign req = {m3_req_i, m2_req_i, m1_req_i, m0_req_i};
// 授权主设备切换
always @ (posedge clk) begin
if (rst == `RstEnable) begin
grant <= grant1;
end else begin
grant <= next_grant;
end
end
// 仲裁逻辑
// 固定优先级仲裁机制
// 优先级由高到低：主设备0，主设备2，主设备1
always @ (*) begin
if (rst == `RstEnable) begin
next_grant = grant1;
grant = grant1;
hold_flag_o = `HoldDisable;
end else begin
case (grant)
grant0: begin
if (req[3]) begin
next_grant = grant3;
hold_flag_o = `HoldEnable;
end else if (req[0]) begin
next_grant = grant0;
hold_flag_o = `HoldEnable;
end else if (req[2]) begin
next_grant = grant2;
hold_flag_o = `HoldEnable;
end else begin
next_grant = grant1;
hold_flag_o = `HoldDisable;
end
end
grant1: begin
if (req[3]) begin
next_grant = grant3;
hold_flag_o = `HoldEnable;
end else if (req[0]) begin
next_grant = grant0;
hold_flag_o = `HoldEnable;
end else if (req[2]) begin
next_grant = grant2;
hold_flag_o = `HoldEnable;
end else begin
next_grant = grant1;
hold_flag_o = `HoldDisable;
end
end
grant2: begin
if (req[3]) begin
next_grant = grant3;
hold_flag_o = `HoldEnable;
end else if (req[0]) begin
next_grant = grant0;
hold_flag_o = `HoldEnable;
end else if (req[2]) begin
next_grant = grant2;
hold_flag_o = `HoldEnable;
end else begin
next_grant = grant1;
hold_flag_o = `HoldDisable;
end
end
grant3: begin
if (req[3]) begin
next_grant = grant3;
hold_flag_o = `HoldEnable;
end else if (req[0]) begin
next_grant = grant0;
hold_flag_o = `HoldEnable;
end else if (req[2]) begin
next_grant = grant2;
hold_flag_o = `HoldEnable;
end else begin
next_grant = grant1;
hold_flag_o = `HoldDisable;
end
end
default: begin
next_grant = grant1;
hold_flag_o = `HoldDisable;
end
endcase
if (req[3]) begin
grant = grant3;
hold_flag_o = `HoldEnable;
end else if (req[0]) begin
grant = grant0;
hold_flag_o = `HoldEnable;
end else if (req[2]) begin
grant = grant2;
hold_flag_o = `HoldEnable;
end else begin
grant = grant1;
hold_flag_o = `HoldDisable;
end
end
end
// 根据授权结果，选择(访问)对应的从设备
// 根据仲裁结果，选择(访问)对应的从设备
always @ (*) begin
if (rst == `RstEnable) begin
m0_ack_o = `RIB_NACK;