//---------------------------------------------------------------------------- // Copyright (C) 2001 Authors // // This source file may be used and distributed without restriction provided // that this copyright statement is not removed from the file and that any // derivative work contains the original copyright notice and the associated // disclaimer. // // This source file is free software; you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published // by the Free Software Foundation; either version 2.1 of the License, or // (at your option) any later version. // // This source is distributed in the hope that it will be useful, but WITHOUT // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public // License for more details. // // You should have received a copy of the GNU Lesser General Public License // along with this source; if not, write to the Free Software Foundation, // Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA // //---------------------------------------------------------------------------- // // *File Name: omsp_execution_unit.v // // *Module Description: // openMSP430 Execution unit // // *Author(s): // - Olivier Girard, olgirard@gmail.com // //---------------------------------------------------------------------------- // $Rev: 34 $ // $LastChangedBy: olivier.girard $ // $LastChangedDate: 2009-12-29 20:10:34 +0100 (Tue, 29 Dec 2009) $ //---------------------------------------------------------------------------- `include "timescale.v" `include "openMSP430_defines.v" module omsp_execution_unit ( // OUTPUTs cpuoff, // Turns off the CPU dbg_reg_din, // Debug unit CPU register data input gie, // General interrupt enable mab, // Memory address bus mb_en, // Memory bus enable mb_wr, // Memory bus write transfer mdb_out, // Memory data bus output oscoff, // Turns off LFXT1 clock input pc_sw, // Program counter software value pc_sw_wr, // Program counter software write scg1, // System clock generator 1. Turns off the SMCLK // INPUTs dbg_halt_st, // Halt/Run status from CPU dbg_mem_dout, // Debug unit data output dbg_reg_wr, // Debug unit CPU register write e_state, // Execution state exec_done, // Execution completed inst_ad, // Decoded Inst: destination addressing mode inst_as, // Decoded Inst: source addressing mode inst_alu, // ALU control signals inst_bw, // Decoded Inst: byte width inst_dest, // Decoded Inst: destination (one hot) inst_dext, // Decoded Inst: destination extended instruction word inst_irq_rst, // Decoded Inst: reset interrupt inst_jmp, // Decoded Inst: Conditional jump inst_sext, // Decoded Inst: source extended instruction word inst_so, // Decoded Inst: Single-operand arithmetic inst_src, // Decoded Inst: source (one hot) inst_type, // Decoded Instruction type mclk, // Main system clock mdb_in, // Memory data bus input pc, // Program counter pc_nxt, // Next PC value (for CALL & IRQ) puc // Main system reset ); // OUTPUTs //========= output cpuoff; // Turns off the CPU output [15:0] dbg_reg_din; // Debug unit CPU register data input output gie; // General interrupt enable output [15:0] mab; // Memory address bus output mb_en; // Memory bus enable output [1:0] mb_wr; // Memory bus write transfer output [15:0] mdb_out; // Memory data bus output output oscoff; // Turns off LFXT1 clock input output [15:0] pc_sw; // Program counter software value output pc_sw_wr; // Program counter software write output scg1; // System clock generator 1. Turns off the SMCLK // INPUTs //========= input dbg_halt_st; // Halt/Run status from CPU input [15:0] dbg_mem_dout; // Debug unit data output input dbg_reg_wr; // Debug unit CPU register write input [3:0] e_state; // Execution state input exec_done; // Execution completed input [7:0] inst_ad; // Decoded Inst: destination addressing mode input [7:0] inst_as; // Decoded Inst: source addressing mode input [11:0] inst_alu; // ALU control signals input inst_bw; // Decoded Inst: byte width input [15:0] inst_dest; // Decoded Inst: destination (one hot) input [15:0] inst_dext; // Decoded Inst: destination extended instruction word input inst_irq_rst; // Decoded Inst: reset interrupt input [7:0] inst_jmp; // Decoded Inst: Conditional jump input [15:0] inst_sext; // Decoded Inst: source extended instruction word input [7:0] inst_so; // Decoded Inst: Single-operand arithmetic input [15:0] inst_src; // Decoded Inst: source (one hot) input [2:0] inst_type; // Decoded Instruction type input mclk; // Main system clock input [15:0] mdb_in; // Memory data bus input input [15:0] pc; // Program counter input [15:0] pc_nxt; // Next PC value (for CALL & IRQ) input puc; // Main system reset //============================================================================= // 1) INTERNAL WIRES/REGISTERS/PARAMETERS DECLARATION //============================================================================= wire [15:0] alu_out; wire [15:0] alu_out_add; wire [3:0] alu_stat; wire [3:0] alu_stat_wr; wire [15:0] op_dst; wire [15:0] op_src; wire [15:0] reg_dest; wire [15:0] reg_src; wire [15:0] mdb_in_bw; wire [15:0] mdb_in_val; wire [3:0] status; //============================================================================= // 2) REGISTER FILE //============================================================================= wire reg_dest_wr = ((e_state==`E_EXEC) & ( (inst_type[`INST_TO] & inst_ad[`DIR] & ~inst_alu[`EXEC_NO_WR]) | (inst_type[`INST_SO] & inst_as[`DIR] & ~(inst_so[`PUSH] | inst_so[`CALL] | inst_so[`RETI])) | inst_type[`INST_JMP])) | dbg_reg_wr; wire reg_sp_wr = (((e_state==`E_IRQ_1) | (e_state==`E_IRQ_3)) & ~inst_irq_rst) | ((e_state==`E_DST_RD) & (inst_so[`PUSH] | inst_so[`CALL])); wire reg_sr_wr = (e_state==`E_DST_RD) & inst_so[`RETI]; wire reg_sr_clr = (e_state==`E_IRQ_2); wire reg_pc_call = ((e_state==`E_EXEC) & inst_so[`CALL]) | ((e_state==`E_DST_WR) & inst_so[`RETI]); wire reg_incr = (exec_done & inst_as[`INDIR_I]) | ((e_state==`E_SRC_RD) & inst_so[`RETI]) | ((e_state==`E_EXEC) & inst_so[`RETI]); assign dbg_reg_din = reg_dest; omsp_register_file register_file_0 ( // OUTPUTs .cpuoff (cpuoff), // Turns off the CPU .gie (gie), // General interrupt enable .oscoff (oscoff), // Turns off LFXT1 clock input .pc_sw (pc_sw), // Program counter software value .pc_sw_wr (pc_sw_wr), // Program counter software write .reg_dest (reg_dest), // Selected register destination content .reg_src (reg_src), // Selected register source content .scg1 (scg1), // System clock generator 1. Turns off the SMCLK .status (status), // R2 Status {V,N,Z,C} // INPUTs .alu_stat (alu_stat), // ALU Status {V,N,Z,C} .alu_stat_wr (alu_stat_wr), // ALU Status write {V,N,Z,C} .inst_bw (inst_bw), // Decoded Inst: byte width .inst_dest (inst_dest), // Register destination selection .inst_src (inst_src), // Register source selection .mclk (mclk), // Main system clock .pc (pc), // Program counter .puc (puc), // Main system reset .reg_dest_val (alu_out), // Selected register destination value .reg_dest_wr (reg_dest_wr), // Write selected register destination .reg_pc_call (reg_pc_call), // Trigger PC update for a CALL instruction .reg_sp_val (alu_out_add), // Stack Pointer next value .reg_sp_wr (reg_sp_wr), // Stack Pointer write .reg_sr_clr (reg_sr_clr), // Status register clear for interrupts .reg_sr_wr (reg_sr_wr), // Status Register update for RETI instruction .reg_incr (reg_incr) // Increment source register ); //============================================================================= // 3) SOURCE OPERAND MUXING //============================================================================= // inst_as[`DIR] : Register direct. -> Source is in register // inst_as[`IDX] : Register indexed. -> Source is in memory, address is register+offset // inst_as[`INDIR] : Register indirect. // inst_as[`INDIR_I]: Register indirect autoincrement. // inst_as[`SYMB] : Symbolic (operand is in memory at address PC+x). // inst_as[`IMM] : Immediate (operand is next word in the instruction stream). // inst_as[`ABS] : Absolute (operand is in memory at address x). // inst_as[`CONST] : Constant. wire src_reg_src_sel = (e_state==`E_IRQ_0) | (e_state==`E_IRQ_2) | ((e_state==`E_SRC_RD) & ~inst_as[`ABS]) | ((e_state==`E_SRC_WR) & ~inst_as[`ABS]) | ((e_state==`E_EXEC) & inst_as[`DIR] & ~inst_type[`INST_JMP]); wire src_reg_dest_sel = (e_state==`E_IRQ_1) | (e_state==`E_IRQ_3) | ((e_state==`E_DST_RD) & (inst_so[`PUSH] | inst_so[`CALL])); wire src_mdb_in_val_sel = ((e_state==`E_DST_RD) & inst_so[`RETI]) | ((e_state==`E_EXEC) & (inst_as[`INDIR] | inst_as[`INDIR_I] | inst_as[`IDX] | inst_as[`SYMB] | inst_as[`ABS])); wire src_inst_dext_sel = ((e_state==`E_DST_RD) & ~(inst_so[`PUSH] | inst_so[`CALL])) | ((e_state==`E_DST_WR) & ~(inst_so[`PUSH] | inst_so[`CALL] | inst_so[`RETI])); wire src_inst_sext_sel = ((e_state==`E_EXEC) & (inst_type[`INST_JMP] | inst_as[`IMM] | inst_as[`CONST] | inst_so[`RETI])); assign op_src = src_reg_src_sel ? reg_src : src_reg_dest_sel ? reg_dest : src_mdb_in_val_sel ? mdb_in_val : src_inst_dext_sel ? inst_dext : src_inst_sext_sel ? inst_sext : 16'h0000; //============================================================================= // 4) DESTINATION OPERAND MUXING //============================================================================= // inst_ad[`DIR] : Register direct. // inst_ad[`IDX] : Register indexed. // inst_ad[`SYMB] : Symbolic (operand is in memory at address PC+x). // inst_ad[`ABS] : Absolute (operand is in memory at address x). wire dst_inst_sext_sel = ((e_state==`E_SRC_RD) & (inst_as[`IDX] | inst_as[`SYMB] | inst_as[`ABS])) | ((e_state==`E_SRC_WR) & (inst_as[`IDX] | inst_as[`SYMB] | inst_as[`ABS])); wire dst_mdb_in_bw_sel = ((e_state==`E_DST_WR) & inst_so[`RETI]) | ((e_state==`E_EXEC) & ~(inst_ad[`DIR] | inst_type[`INST_JMP] | inst_type[`INST_SO]) & ~inst_so[`RETI]); wire dst_fffe_sel = (e_state==`E_IRQ_0) | (e_state==`E_IRQ_1) | (e_state==`E_IRQ_3) | ((e_state==`E_DST_RD) & (inst_so[`PUSH] | inst_so[`CALL]) & ~inst_so[`RETI]); wire dst_reg_dest_sel = ((e_state==`E_DST_RD) & ~(inst_so[`PUSH] | inst_so[`CALL] | inst_ad[`ABS] | inst_so[`RETI])) | ((e_state==`E_DST_WR) & ~inst_ad[`ABS]) | ((e_state==`E_EXEC) & (inst_ad[`DIR] | inst_type[`INST_JMP] | inst_type[`INST_SO]) & ~inst_so[`RETI]); assign op_dst = dbg_halt_st ? dbg_mem_dout : dst_inst_sext_sel ? inst_sext : dst_mdb_in_bw_sel ? mdb_in_bw : dst_reg_dest_sel ? reg_dest : dst_fffe_sel ? 16'hfffe : 16'h0000; //============================================================================= // 5) ALU //============================================================================= wire exec_cycle = (e_state==`E_EXEC); omsp_alu alu_0 ( // OUTPUTs .alu_out (alu_out), // ALU output value .alu_out_add (alu_out_add), // ALU adder output value .alu_stat (alu_stat), // ALU Status {V,N,Z,C} .alu_stat_wr (alu_stat_wr), // ALU Status write {V,N,Z,C} // INPUTs .dbg_halt_st (dbg_halt_st), // Halt/Run status from CPU .exec_cycle (exec_cycle), // Instruction execution cycle .inst_alu (inst_alu), // ALU control signals .inst_bw (inst_bw), // Decoded Inst: byte width .inst_jmp (inst_jmp), // Decoded Inst: Conditional jump .inst_so (inst_so), // Single-operand arithmetic .op_dst (op_dst), // Destination operand .op_src (op_src), // Source operand .status (status) // R2 Status {V,N,Z,C} ); //============================================================================= // 6) MEMORY INTERFACE //============================================================================= // Detect memory read/write access assign mb_en = ((e_state==`E_IRQ_1) & ~inst_irq_rst) | ((e_state==`E_IRQ_3) & ~inst_irq_rst) | ((e_state==`E_SRC_RD) & ~inst_as[`IMM]) | (e_state==`E_SRC_WR) | ((e_state==`E_EXEC) & inst_so[`RETI]) | (e_state==`E_DST_RD) | (e_state==`E_DST_WR); wire [1:0] mb_wr_msk = inst_alu[`EXEC_NO_WR] ? 2'b00 : ~inst_bw ? 2'b11 : alu_out_add[0] ? 2'b10 : 2'b01; assign mb_wr = ({2{(e_state==`E_IRQ_1)}} | {2{(e_state==`E_IRQ_3)}} | {2{(e_state==`E_DST_WR)}} | {2{(e_state==`E_SRC_WR)}}) & mb_wr_msk; // Memory address bus assign mab = alu_out_add[15:0]; // Memory data bus output reg [15:0] mdb_out_nxt; always @(posedge mclk or posedge puc) if (puc) mdb_out_nxt <= 16'h0000; else if (e_state==`E_DST_RD) mdb_out_nxt <= pc_nxt; else if ((e_state==`E_EXEC & ~inst_so[`CALL]) | (e_state==`E_IRQ_0) | (e_state==`E_IRQ_2)) mdb_out_nxt <= alu_out; assign mdb_out = inst_bw ? {2{mdb_out_nxt[7:0]}} : mdb_out_nxt; // Format memory data bus input depending on BW reg mab_lsb; always @(posedge mclk or posedge puc) if (puc) mab_lsb <= 1'b0; else if (mb_en) mab_lsb <= alu_out_add[0]; assign mdb_in_bw = ~inst_bw ? mdb_in : mab_lsb ? {2{mdb_in[15:8]}} : mdb_in; // Memory data bus input buffer (buffer after a source read) reg mdb_in_buf_en; always @(posedge mclk or posedge puc) if (puc) mdb_in_buf_en <= 1'b0; else mdb_in_buf_en <= (e_state==`E_SRC_RD); reg mdb_in_buf_valid; always @(posedge mclk or posedge puc) if (puc) mdb_in_buf_valid <= 1'b0; else if (e_state==`E_EXEC) mdb_in_buf_valid <= 1'b0; else if (mdb_in_buf_en) mdb_in_buf_valid <= 1'b1; reg [15:0] mdb_in_buf; always @(posedge mclk or posedge puc) if (puc) mdb_in_buf <= 16'h0000; else if (mdb_in_buf_en) mdb_in_buf <= mdb_in_bw; assign mdb_in_val = mdb_in_buf_valid ? mdb_in_buf : mdb_in_bw; endmodule // omsp_execution_unit `include "openMSP430_undefines.v"