1 jr指令分析

instructionoprsrtrdshamtfunc

jr	000000	rs	00000	00000	00000	001000

舉例：jr $31
功能：PC <- （$31）

這是個(gè)跳轉(zhuǎn)指令，將指定寄存器的值，放入PC中，是無(wú)條件跳轉(zhuǎn)。

我們需要

更新PC，加一個(gè)多路選擇器，實(shí)現(xiàn)+4和PC <- (reg)兩種選擇

增加控制信號(hào)Jrn，標(biāo)識(shí)jr指令

2 新的數(shù)據(jù)通路

3 器件修改

控制器，控制信號(hào)輸出Jrn標(biāo)識(shí)jr指令

PC，增加輸入信號(hào)jr和輸入數(shù)據(jù)32位寄存器值

控制信號(hào)：

instructionopfuncALUopRegWriteSftmdJrn

jr	000000	001000	1111	0	0	1

4 代碼實(shí)現(xiàn)

4.1 PC

增加了輸入信號(hào)和輸入數(shù)據(jù)，更改了原來(lái)的pcNew的名稱(chēng)為pcOrigin，增加了多路選擇器。

`timescale 1ns / 1ps // // Company: // Engineer: // // Create Date: 2020/11/12 20:31:59 // Design Name: // Module Name: pc_1 // Project Name: // Target Devices: // Tool Versions: // Description: // // Dependencies: // // Revision: // Revision 0.01 - File Created // Additional Comments: // //module pc_1(input clk,input rst_n,// pc datainput [31:0] pcOrigin, // The PC value is from pcOld.input [31:0] JrPC, // jr instruction,from reg files.// pc controlinput Jrn, // jr instruction.output [31:0] pcOld);reg [31:0] pc = 0; assign pcOld = pc;wire [31:0] pcSelect; // new pc dataassign pcSelect = (Jrn == 0) ? (pcOrigin + 4): JrPC;// Update PC register always @(posedge clk) beginif(rst_n == 1) // Xilinx 官方推薦：reset 高電平有效beginpc <= 0;endelsebeginpc <= pcSelect;end endendmodule

4.2 control

`timescale 1ns / 1ps // // Company: // Engineer: // // Create Date: 2020/11/14 22:30:48 // Design Name: // Module Name: control_1 // Project Name: // Target Devices: // Tool Versions: // Description: // // Dependencies: // // Revision: // Revision 0.01 - File Created // Additional Comments: // //module control_1(input [5:0] op,input [5:0] func,output reg RegWrite,output reg Sftmd, // indicate the instruction is sll/srl/sraoutput reg [3:0] ALUop,output reg Jrn // jr instruction);always @(*) beginif(op == 6'b0)begincase (func)6'b100000: // addbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0000;Jrn <= 0;end6'b100001: // addubeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0001;Jrn <= 0;end6'b100010: // subbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0010;Jrn <= 0;end6'b100011: // sububeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0011;Jrn <= 0;end6'b100100: // andbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0100;Jrn <= 0;end6'b100101: // orbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0101;Jrn <= 0;end6'b100110: // xorbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0110;Jrn <= 0;end6'b100111: // norbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b0111;Jrn <= 0;end6'b101010: // sltbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b1000;Jrn <= 0;end6'b101011: // sltubeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b1001;Jrn <= 0;end6'b000100: // sllvbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b1010;Jrn <= 0;end6'b000110: // srlvbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b1011;Jrn <= 0;end6'b000111: // sravbeginRegWrite <= 1;Sftmd <= 0;ALUop <= 4'b1100;Jrn <= 0;end6'b000000: // sllbeginRegWrite <= 1;Sftmd <= 1;ALUop <= 4'b1010;Jrn <= 0;end6'b000010: // srlbeginRegWrite <= 1;Sftmd <= 1;ALUop <= 4'b1011;Jrn <= 0;end6'b000011: // srabeginRegWrite <= 1;Sftmd <= 1;ALUop <= 4'b1100;Jrn <= 0;end6'b001000:beginRegWrite <= 0;Sftmd <= 0;ALUop <= 4'b1111;Jrn <= 1;enddefault:beginRegWrite <= 0;Sftmd <= 0;ALUop <= 4'b1111;Jrn <= 0;endendcaseendelsebeginRegWrite <= 0;Sftmd <= 0;ALUop <= 4'b1111;Jrn <= 0;end endendmodule

4.3 datapath

`timescale 1ns / 1ps // // Company: // Engineer: // // Create Date: 2020/11/27 11:41:34 // Design Name: // Module Name: datapath_1 // Project Name: // Target Devices: // Tool Versions: // Description: 僅僅實(shí)現(xiàn)了幾個(gè)簡(jiǎn)單的R類(lèi)指令的最簡(jiǎn)單的數(shù)據(jù)通路，不與外界交互 // // Dependencies: // // Revision: // Revision 0.01 - File Created // Additional Comments: // //module datapath_1(input clk,input rst_n,output [31:0] result // 測(cè)試syntheses，沒(méi)有輸出的模塊是恐怖的);/******** PC ********/// pc_1 Inputs wire Jrn; wire [31:0] JrPC;// pc_1 Outputs wire [31:0] pcOld;pc_1 u_pc_1 (.clk ( clk ),.rst_n ( rst_n ),.pcOrigin ( pcOld ),.JrPC ( JrPC ),.Jrn ( Jrn ),.pcOld ( pcOld ));/******** Instruction ROM ********/// blk_mem_gen_0 Inputs // wire [13:0] addra = pcOld[15:2];// blk_mem_gen_0 Outputs // instructions wire [31:0] instruction;blk_mem_gen_0 u_blk_mem_gen_0 (.clka ( clk ),.addra ( pcOld[15:2] ),.douta ( instruction ));/******** Reg Files ********/// reg_files_1 Inputs wire [31:0] ALUresult;/// wire [4:0] rA = instruction[25:21]; /// wire [4:0] rB = instruction[20:16]; /// wire [4:0] rW = instruction[15:11]; /// wire [31:0] writeData = ALUresult; wire RegWrite;// reg_files_1 Outputs wire [31:0] A; // rs wire [31:0] B; // rt assign JrPC = A;reg_files_1 u_reg_files_1 (.clk ( clk ),.rst_n ( rst_n ),.rA ( instruction[25:21] ),.rB ( instruction[20:16] ),.rW ( instruction[15:11] ),.writeData ( ALUresult ),.RegWrite ( RegWrite ),.A ( A ),.B ( B ));/******** ALU ********/// ALU_1 Inputs // wire [31:0] A; // wire [31:0] B; wire [3:0] ALUop; wire Sftmd;// ALU_1 Outputs // wire [31:0] ALUresult = writeData; // 【不能用！傳輸方向不對(duì)】ALU_1 u_ALU_1 (.A ( A ),.B ( B ),.shamt ( instruction[10:6]),.ALUop ( ALUop ),.Sftmd ( Sftmd ),.ALUresult ( ALUresult ));/******** controler ********/// control_1 Inputs // wire [5:0] op = instruction[31:26]; // wire [5:0] func = instruction[5:0];// control_1 Outputs // wire RegWrite // wire [3:0] ALUop;control_1 u_control_1 (.op ( instruction[31:26] ),.func ( instruction[5:0] ),.RegWrite ( RegWrite ),.Sftmd ( Sftmd ),.ALUop ( ALUop ),.Jrn ( Jrn ));assign result = ALUresult;endmodule

5 測(cè)試

可以觀察到跳變了。

nop add $1,$2,$3 # $1 = 2 + 3 = 5 addu $2,$4,$1 # $2 = 4 + 5 = 9 sub $4,$2,$1 # $4 = 9 - 5 = 4 subu $5,$4,$3 # $5 = 4 - 3 = 1and $6,$7,$8 # $6 = 0111 and 1000 = 0 or $7,$6,$8 # $7 = 0 or 1000 = 8 xor $7,$6,$8 # $7 = 0000 xor 1000 = 1000 = 8 nor $8,$7,$6 # $8 = not (1000 or 0) = 11111111111110111slt $10,$11,$12 # $10 = 11 < 12 = 1 # 應(yīng)該用負(fù)數(shù)驗(yàn)證，以后再說(shuō) sltu $10,$12,$11 # $10 = 12 > 11 = 0# sllv $12,$5,$13 # $12 = 1101 << 1 = 1101_0 = 1A 【注意此處的倒置問(wèn)題！ sllv rd,rt,rs】 # srlv $12,$5,$13 # $12 = 1101 >> 1 = 110 = 6 # srav $14,$5,$15 # $14 = 1111 >>> 1 = 111 = 7 應(yīng)該用負(fù)數(shù)驗(yàn)證，以后再說(shuō)# 上面3條是錯(cuò)誤的！我們應(yīng)該改的不是使用，而是內(nèi)部運(yùn)算邏輯 # 對(duì)于使用者來(lái)說(shuō)，邏輯就是 $13 << $5 # 而實(shí)際的編碼是 rt = $13，rs = $5，這與一般的指令不一樣 # 因此，我們?cè)贏LU運(yùn)算中 rt--B，rs--A，應(yīng)該是 【B << A】，而不是 A >> B。 sllv $12,$13,$5 # $12 = 1101 << 1 = 1101_0 = 1A srlv $12,$13,$5 # $12 = 1101 >> 1 = 110 = 6 srav $14,$15,$5 # $14 = 1111 >>> 1 = 111 = 7 應(yīng)該用負(fù)數(shù)驗(yàn)證，以后再說(shuō)sll $16,$17,2 # $16 = 1_0001 << 2 = 100_0100 = 44 srl $16,$18,2 # $16 = 1_0010 >> 2 = 0100 = 4 sra $16,$19,2 # 應(yīng)該用負(fù)數(shù)驗(yàn)證，以后再說(shuō) $16 = 4jr $16 # PC = 4

編碼

memory_initialization_radix = 16; memory_initialization_vector = 00000000, 00430820, 00811021, 00412022, 00832823, 00e83024, 00c83825, 00c83826, 00e64027, 016c502a, 018b502b, 00ad6004, 00ad6006, 00af7007, 00118080, 00128082, 00138083, 02000008;

測(cè)試完成。

總結(jié)

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