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Pipelining_the_CPU.tlv
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\m4_TLV_version 1d: tl-x.org
\SV
// This code can be found in: https://github.com/stevehoover/RISC-V_MYTH_Workshop
m4_include_lib(['https://raw.githubusercontent.com/stevehoover/RISC-V_MYTH_Workshop/c1719d5b338896577b79ee76c2f443ca2a76e14f/tlv_lib/risc-v_shell_lib.tlv'])
\SV
m4_makerchip_module // (Expanded in Nav-TLV pane.)
\TLV
// /====================\
// | Sum 1 to 9 Program |
// \====================/
//
// Program for MYTH Workshop to test RV32I
// Add 1,2,3,...,9 (in that order).
//
// Regs:
// r10 (a0): In: 0, Out: final sum
// r12 (a2): 10
// r13 (a3): 1..10
// r14 (a4): Sum
//
// External to function:
m4_asm(ADD, r10, r0, r0) // Initialize r10 (a0) to 0.
// Function:
m4_asm(ADD, r14, r10, r0) // Initialize sum register a4 with 0x0
m4_asm(ADDI, r12, r10, 1010) // Store count of 10 in register a2.
m4_asm(ADD, r13, r10, r0) // Initialize intermediate sum register a3 with 0
// Loop:
m4_asm(ADD, r14, r13, r14) // Incremental addition
m4_asm(ADDI, r13, r13, 1) // Increment intermediate register by 1
m4_asm(BLT, r13, r12, 1111111111000) // If a3 is less than a2, branch to label named <loop>
m4_asm(ADD, r10, r14, r0) // Store final result to register a0 so that it can be read by main program
// Optional:
// m4_asm(JAL, r7, 00000000000000000000) // Done. Jump to itself (infinite loop). (Up to 20-bit signed immediate plus implicit 0 bit (unlike JALR) provides byte address; last immediate bit should also be 0)
m4_define_hier(['M4_IMEM'], M4_NUM_INSTRS)
|cpu
@0
$reset = *reset;
//Fetch
// Next PC
$pc[31:0] = (>>1$reset) ? '0 :
(>>3$taken_br) ? >>3$br_tgt_pc : >>1$inc_pc;
$imem_rd_en = !$reset;
$imem_rd_addr[31:0] = $pc[M4_IMEM_INDEX_CNT+1:2];
@1
$instr[31:0] = $imem_rd_data[31:0];
$inc_pc[31:0] = $pc + 32'd4;
// Decode
$is_i_instr = $instr[6:2] ==? 5'b0000x ||
$instr[6:2] ==? 5'b001x0 ||
$instr[6:2] == 5'b11001;
$is_r_instr = $instr[6:2] ==? 5'b01011 ||
$instr[6:2] ==? 5'b10100 ||
$instr[6:2] ==? 5'b0110x;
$is_b_instr = $instr[6:2] == 5'b11000;
$is_u_instr = $instr[6:2] == 5'b0x101;
$is_s_instr = $instr[6:2] == 5'b0100x;
$is_j_instr = $instr[6:2] == 5'b11011;
$imm[31:0] = $is_i_instr ? { {21{$instr[31]}} , $instr[30:20] } :
$is_s_instr ? { {21{$instr[31]}} , $instr[30:25] , $instr[11:8] , $instr[7] } :
$is_b_instr ? { {20{$instr[31]}} , $instr[7] , $instr[30:25] , $instr[11:8] , 1'b0} :
$is_u_instr ? { $instr[31:12] , 12'b0} :
$is_j_instr ? { {12{$instr[31]}} , $instr[19:12] , $instr[20] , $instr[30:21] , 1'b0} : 32'b0;
$rs2_valid = $is_r_instr || $is_s_instr || $is_b_instr;
$rs1_valid = $is_r_instr || $is_s_instr || $is_b_instr || $is_i_instr;
$rd_valid = $is_r_instr || $is_i_instr || $is_u_instr || $is_j_instr;
$funct3_valid = $is_r_instr || $is_s_instr || $is_b_instr || $is_i_instr;
$funct7_valid = $is_r_instr;
?$rs2_valid
$rs2[4:0] = $instr[24:20];
?$rs1_valid
$rs1[4:0] = $instr[19:15];
?$rd_valid
$rd[4:0] = $instr[11:7];
?$funct3_valid
$funct3[2:0] = $instr[14:12];
?$funct7_valid
$funct7[6:0] = $instr[31:25];
$opcode[6:0] = $instr[6:0];
$dec_bits[10:0] = {$funct7[5],$funct3,$opcode};
// Branch Instruction
$is_beq = $dec_bits ==? 11'bx_000_1100011;
$is_bne = $dec_bits ==? 11'bx_001_1100011;
$is_blt = $dec_bits ==? 11'bx_100_1100011;
$is_bge = $dec_bits ==? 11'bx_101_1100011;
$is_bltu = $dec_bits ==? 11'bx_110_1100011;
$is_bgeu = $dec_bits ==? 11'bx_111_1100011;
// Arithmetic Instruction
$is_add = $dec_bits ==? 11'b0_000_0110011;
$is_addi = $dec_bits ==? 11'bx_000_0010011;
$is_or = $dec_bits ==? 11'b0_110_0110011;
$is_ori = $dec_bits ==? 11'bx_110_0010011;
$is_xor = $dec_bits ==? 11'b0_100_0110011;
$is_xori = $dec_bits ==? 11'bx_100_0010011;
$is_and = $dec_bits ==? 11'b0_111_0110011;
$is_andi = $dec_bits ==? 11'bx_111_0010011;
$is_sub = $dec_bits ==? 11'b1_000_0110011;
$is_slti = $dec_bits ==? 11'bx_010_0010011;
$is_sltiu = $dec_bits ==? 11'bx_011_0010011;
$is_slli = $dec_bits ==? 11'b0_001_0010011;
$is_srli = $dec_bits ==? 11'b0_101_0010011;
$is_srai = $dec_bits ==? 11'b1_101_0010011;
$is_sll = $dec_bits ==? 11'b0_001_0110011;
$is_slt = $dec_bits ==? 11'b0_010_0110011;
$is_sltu = $dec_bits ==? 11'b0_011_0110011;
$is_srl = $dec_bits ==? 11'b0_101_0110011;
$is_sra = $dec_bits ==? 11'b1_101_0110011;
// Load Instruction
$is_load = $dec_bits ==? 11'bx_xxx_0000011;
// Store Instruction
$is_sb = $dec_bits ==? 11'bx_000_0100011;
$is_sh = $dec_bits ==? 11'bx_001_0100011;
$is_sw = $dec_bits ==? 11'bx_010_0100011;
// Jump Instruction
$lui = $dec_bits ==? 11'bx_xxx_0110111;
$auipc = $dec_bits ==? 11'bx_xxx_0010111;
$jal = $dec_bits ==? 11'bx_xxx_1101111;
$jalr = $dec_bits ==? 11'bx_000_1100111;
@2
// Register File Read
$rf_rd_en1 = $rs1_valid;
?$rf_rd_en1
$rf_rd_index1[4:0] = $rs1[4:0];
$rf_rd_en2 = $rs2_valid;
?$rf_rd_en2
$rf_rd_index2[4:0] = $rs2[4:0];
// Branch Target PC
$br_tgt_pc[31:0] = $pc + $imm;
// Input signals to ALU
$src1_value[31:0] = ((>>1$rd == $rs1) && >>1$rf_wr_en) ? >>1$result : $rf_rd_data1[31:0];
$src2_value[31:0] = ((>>1$rd == $rs2) && >>1$rf_wr_en) ? >>1$result : $rf_rd_data2[31:0];
@3
// ALU
$sltu_result = $src1_value < $src2_value ;
$sltiu_result = $src1_value < $imm ;
$result[31:0] = $is_addi ? $src1_value + $imm :
$is_add ? $src1_value + $src2_value :
$is_or ? $src1_value | $src2_value :
$is_ori ? $src1_value | $imm :
$is_xor ? $src1_value ^ $src2_value :
$is_xori ? $src1_value ^ $imm :
$is_and ? $src1_value & $src2_value :
$is_andi ? $src1_value & $imm :
$is_sub ? $src1_value - $src2_value :
$is_slti ? (($src1_value[31] == $imm[31]) ? $sltiu_result : {31'b0,$src1_value[31]}) :
$is_sltiu ? $sltiu_result :
$is_slli ? $src1_value << $imm[5:0] :
$is_srli ? $src1_value >> $imm[5:0] :
$is_srai ? ({{32{$src1_value[31]}}, $src1_value} >> $imm[4:0]) :
$is_sll ? $src1_value << $src2_value[4:0] :
$is_slt ? (($src1_value[31] == $src2_value[31]) ? $sltu_result : {31'b0,$src1_value[31]}) :
$is_sltu ? $sltu_result :
$is_srl ? $src1_value >> $src2_value[5:0] :
$is_sra ? ({{32{$src1_value[31]}}, $src1_value} >> $src2_value[4:0]) :
$lui ? ({$imm[31:12], 12'b0}) :
$auipc ? $pc + $imm :
$jal ? $pc + 4 :
$jalr ? $pc + 4 : 32'bx;
// Register File Write
$rf_wr_en = $valid ? (($rd == 5'b0) ? 1'b0 : $rd_valid) : 1'b0;
?$rf_wr_en
$rf_wr_index[4:0] = $rd[4:0];
$rf_wr_data[31:0] = $result[31:0];
// Branch
$taken_br = $is_beq ? ($src1_value == $src2_value) :
$is_bne ? ($src1_value != $src2_value) :
$is_blt ? (($src1_value < $src2_value) ^ ($src1_value[31] != $src2_value[31])) :
$is_bge ? (($src1_value >= $src2_value) ^ ($src1_value[31] != $src2_value[31])) :
$is_bltu ? ($src1_value < $src2_value) :
$is_bgeu ? ($src1_value >= $src2_value) : 1'b0;
$valid_taken_br = $valid && $taken_br;
$valid = !(>>1$valid_taken_br || >>2$valid_taken_br);
// Note: Because of the magic we are using for visualisation, if visualisation is enabled below,
// be sure to avoid having unassigned signals (which you might be using for random inputs)
// other than those specifically expected in the labs. You'll get strange errors for these.
`BOGUS_USE($is_beq $is_bne $is_blt $is_bge $is_bltu $is_bgeu)
// Assert these to end simulation (before Makerchip cycle limit).
*passed = |cpu/xreg[10]>>5$value == (1+2+3+4+5+6+7+8+9);
*failed = 1'b0;
// Macro instantiations for:
// o instruction memory
// o register file
// o data memory
// o CPU visualization
|cpu
m4+imem(@1) // Args: (read stage)
m4+rf(@2, @3) // Args: (read stage, write stage) - if equal, no register bypass is required
//m4+dmem(@4) // Args: (read/write stage)
m4+cpu_viz(@4) // For visualisation, argument should be at least equal to the last stage of CPU logic
// @4 would work for all labs
\SV
endmodule