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cpu_core.tlv
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\m4_TLV_version 1d: tl-x.org
\SV
// This code can be found in: https://github.com/stevehoover/LF-Building-a-RISC-V-CPU-Core/risc-v_shell.tlv
m4_include_lib(['https://raw.githubusercontent.com/stevehoover/warp-v_includes/1d1023ccf8e7b0a8cf8e8fc4f0a823ebb61008e3/risc-v_defs.tlv'])
m4_include_lib(['https://raw.githubusercontent.com/stevehoover/LF-Building-a-RISC-V-CPU-Core/main/lib/risc-v_shell_lib.tlv'])
m4_test_prog()
\SV
m4_makerchip_module // (Expanded in Nav-TLV pane.)
/* verilator lint_on WIDTH */
\TLV
$reset = *reset;
//1.- PC
$next_pc[31:0] = $reset ? 32'b0 :
$taken_br | $is_jal ? $br_tgt_pc :
$is_jalr ? $jalr_tgt_pc :
$pc + 32'b100;
$pc[31:0] = >>1$next_pc;
//Branch handling
$is_b = $is_beq || $is_bne || $is_blt || $is_bge || $is_bltu || $is_bgeu;
$taken_br = $is_b ?
($is_beq && ($src1_value == $src2_value) ? 1'b1 :
$is_bne && ($src1_value != $src2_value) ? 1'b1 :
$is_blt && (($src1_value < $src2_value) ^ ($src1_value[4] != $src2_value[4])) ? 1'b1 :
$is_bge && (($src1_value >= $src2_value) ^ ($src1_value[4] != $src2_value[4])) ? 1'b1 :
$is_bltu && ($src1_value < $src2_value) ? 1'b1 :
$is_bgeu && ($src1_value >= $src2_value) ? 1'b1 :1'b0) :
1'b0;
$br_tgt_pc[31:0] = $pc + $imm;
$jalr_tgt_pc[31:0] = $src1_value + $imm;
//2.- IMem
`READONLY_MEM($addr, $$read_data[31:0])
$addr[31:0] = $pc;
$instr[31:0] = $read_data;
//3.- Dec
//Instruction type
$is_u_instr = $instr[6:2] ==? 5'b0x101;
$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'b01100 ||
$instr[6:2] == 5'b01110 ||
$instr[6:2] == 5'b10100;
$is_s_instr = $instr[6:2] ==? 5'b0100x;
$is_b_instr = $instr[6:2] == 5'b11000;
$is_j_instr = $instr[6:2] == 5'b11011;
//Instruction bit fields
$opcode[6:0] = $instr[6:0];
$rd[4:0] = $instr[11:7];
$rs1[4:0] = $instr[19:15];
$rs2[4:0] = $instr[24:20];
$funct3[2:0] = $instr[14:12];
$funct7[6:0] = $instr[31:25];
//Valid field signals
$rd_valid = $rd != 5'b0 && ($is_r_instr || $is_i_instr || $is_u_instr || $is_j_instr);
$rs1_valid = $is_r_instr || $is_i_instr || $is_s_instr || $is_b_instr;
$rs2_valid = $is_r_instr || $is_s_instr || $is_b_instr;
$funct3_valid = $is_r_instr || $is_i_instr || $is_s_instr || $is_b_instr;
$funct7_valid = $is_r_instr;
$imm_valid = ~$is_r_instr;
//Immediate value
$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[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; //Default
//Instructions
$dec_bits[10:0] = {$instr[30], $funct3, $opcode};
$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;
$is_addi = $dec_bits ==? 11'bx_000_0010011;
$is_add = $dec_bits ==? 11'b0_000_0110011;
$is_lui = $dec_bits ==? 11'bx_xxx_0110111;
$is_auipc = $dec_bits ==? 11'bx_xxx_0010111;
$is_jal = $dec_bits ==? 11'bx_xxx_1101111;
$is_jalr = $dec_bits ==? 11'bx_000_1100111;
$is_slti = $dec_bits ==? 11'bx_010_0010011;
$is_sltiu = $dec_bits ==? 11'bx_011_0010011;
$is_xori = $dec_bits ==? 11'bx_100_0010011;
$is_ori = $dec_bits ==? 11'bx_110_0010011;
$is_andi = $dec_bits ==? 11'bx_111_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_sub = $dec_bits ==? 11'b1_000_0110011;
$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_xor = $dec_bits ==? 11'b0_100_0110011;
$is_srl = $dec_bits ==? 11'b0_101_0110011;
$is_sra = $dec_bits ==? 11'b1_101_0110011;
$is_or = $dec_bits ==? 11'b0_110_0110011;
$is_and = $dec_bits ==? 11'b0_111_0110011;
//This implementation will treat all loads the same:
$is_load = $dec_bits ==? 11'bx_xxx_0000011;
//No need to decode stores (already identified with is_s_instr)
// Assert these to end simulation (before Makerchip cycle limit).
m4+tb()
*failed = *cyc_cnt > M4_MAX_CYC;
//4.- RF-R + 6.- RF-W
//Multiplexor to choose between ALU results and load instructions
$rf_w[31:0] = $is_load ? $ld_data : $result;
m4+rf(32, 32, $reset, $rd_valid, $rd[4:0], $rf_w[31:0], $rs1_valid, $rs1[4:0], $src1_value, $rs2_valid, $rs2[4:0], $src2_value)
//5.- ALU
//Subexpressions
//SLTU and SLTIU (Set if Less Than (Immediate), Unisgned) results:
$sltu_rslt[31:0] = {31'b0, $src1_value < $src2_value};
$sltiu_rslt[31:0] = {31'b0, $src1_value < $imm};
//SRA and SRAI (Shift Right, Arithmetic (Immediate) results:
//sign-extended src1
$sext_src1[63:0] = {{32{$src1_value[31]}}, $src1_value[31:0]};
//64-bit sign-extended results, to be truncated
$sra_rslt[63:0] = $sext_src1 >> $src2_value[4:0];
$srai_rslt[63:0] = $sext_src1 >> $imm[4:0];
$result[31:0] = $is_andi ? $src1_value & $imm :
$is_ori ? $src1_value | $imm :
$is_xori ? $src1_value ^ $imm :
$is_addi | $is_r_instr | $is_load ? $src1_value + $imm :
$is_slli ? $src1_value << $imm[4:0] :
$is_srli ? $src1_value >> $imm[4:0] :
$is_and ? $src1_value & $src2_value :
$is_or ? $src1_value | $src2_value :
$is_xor ? $src1_value ^ $src2_value :
$is_add ? $src1_value + $src2_value :
$is_sub ? $src1_value - $src2_value :
$is_sll ? $src1_value << $src2_value[4:0] :
$is_srl ? $src1_value >> $src2_value[4:0] :
$is_sltu ? $sltu_rslt :
$is_sltiu ? $sltiu_rslt :
$is_lui ? {$imm[31:12], 12'b0} :
$is_auipc ? $pc + $imm :
$is_jal ? $pc + 32'd4 :
$is_jalr ? $pc + 32'd4 :
$is_slt ? $src1_value[31] == $src2_value[31] ?
$sltu_rslt :
{31'b0, $src1_value[31]} :
$is_slti ? $src1_value[31] == $imm[31] ?
$sltiu_rslt :
{31'b0, $src1_value[31]} :
$is_sra ? $sra_rslt[31:0] :
$is_srai ? $srai_rslt[31:0] :
32'b0;
m4+dmem(32, 32, $reset, $result[6:2], $is_s_instr, $src2_value[31:0], $is_load, $ld_data)
m4+cpu_viz()
\SV
endmodule