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https://github.com/sxpert/hp-saturn
synced 2024-11-16 19:50:19 +01:00
start implementing jump instructions
This commit is contained in:
Raphaël Jacquot
parent
d17a4eb533
commit
631b7f9153
4 changed files with 108 additions and 7 deletions
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@ -125,6 +125,8 @@ saturn_inst_decoder instruction_decoder(
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.o_alu_imm_value (dec_alu_imm_value),
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.o_alu_opcode (dec_alu_opcode),
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.o_jump_length (dec_jump_length),
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.o_instr_type (dec_instr_type),
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.o_instr_decoded (dec_instr_decoded),
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.o_instr_execute (dec_instr_execute)
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@ -136,6 +138,8 @@ wire [4:0] dec_alu_reg_src_2;
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wire [3:0] dec_alu_imm_value;
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wire [4:0] dec_alu_opcode;
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wire [2:0] dec_jump_length;
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wire [3:0] dec_instr_type;
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wire [0:0] dec_instr_decoded;
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wire [0:0] dec_instr_execute;
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@ -151,6 +155,8 @@ wire [0:0] aluop_copy = (dec_alu_opcode == `ALU_OP_COPY);
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wire [0:0] inst_alu_p_eq_n = aluop_copy && reg_dest_p && reg_src_1_imm;
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wire [0:0] inst_alu_other = !(inst_alu_p_eq_n);
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wire [0:0] inst_jump = (dec_instr_type == `INSTR_TYPE_JUMP);
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/**************************************************************************************************
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*
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* registers module (contains A, B, C, D, R0, R1, R2, R3, R4)
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@ -174,7 +180,9 @@ saturn_regs_pc_rstk regs_pc_rstk (
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.i_bus_busy (i_bus_busy),
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.i_nibble (i_nibble),
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.i_jump_instr (inst_jump),
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.i_jump_length (dec_jump_length),
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.o_current_pc (reg_PC)
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);
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@ -200,6 +208,8 @@ reg [4:0] bus_program[0:31];
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reg [4:0] bus_prog_addr;
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reg [2:0] addr_nibble_ptr;
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reg [2:0] jump_counter;
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wire [3:0] reg_PC_nibble = reg_PC[addr_nibble_ptr*4+:4];
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assign o_program_data = bus_program[i_program_address];
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@ -213,6 +223,8 @@ initial begin
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control_unit_ready = 1'b0;
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bus_prog_addr = 5'd0;
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addr_nibble_ptr = 3'd0;
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jump_counter = 3'd0;
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/* registers */
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reg_P = 4'b0;
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@ -278,7 +290,7 @@ always @(posedge i_clk) begin
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// `ifdef SIM
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// $display("CTRL %0d: [%d] starting to do things", i_phase, i_cycle_ctr);
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// `endif
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if (i_cycle_ctr == 10) begin
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if (i_cycle_ctr == 15) begin
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control_unit_error <= 1'b1;
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$display("CTRL %0d: [%d] enough cycles for now", i_phase, i_cycle_ctr);
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end
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@ -307,11 +319,22 @@ always @(posedge i_clk) begin
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* the general case
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*/
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end
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`INSTR_TYPE_JUMP: begin
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$display("CTRL %0d: [%d] JUMP instruction", i_phase, i_cycle_ctr);
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jump_counter <= 1'b0;
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end
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default: begin
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$display("CTRL %0d: [%d] unsupported instruction", i_phase, i_cycle_ctr);
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end
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endcase
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end
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if (i_phases[2] && ! dec_instr_execute) begin
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if (inst_jump) begin
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// $display("CTRL %0d: [%d] JUMP nibble %0d : %h", i_phase, i_cycle_ctr, jump_counter, i_nibble);
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jump_counter <= jump_counter + 3'd1;
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end
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end
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end
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if (i_reset) begin
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@ -323,6 +346,8 @@ always @(posedge i_clk) begin
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bus_prog_addr <= 5'd0;
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addr_nibble_ptr <= 3'd0;
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jump_counter <= 3'd0;
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/* registers */
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reg_P <= 4'b0;
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end
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@ -98,6 +98,7 @@
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`define INSTR_TYPE_NOP 0
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`define INSTR_TYPE_ALU 1
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`define INSTR_TYPE_JUMP 2
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`define INSTR_TYPE_NONE 15
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@ -44,6 +44,8 @@ module saturn_inst_decoder (
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o_alu_imm_value,
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o_alu_opcode,
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o_jump_length,
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o_instr_type,
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o_instr_decoded,
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o_instr_execute,
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@ -73,6 +75,8 @@ output reg [4:0] o_alu_reg_src_2;
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output reg [3:0] o_alu_imm_value;
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output reg [4:0] o_alu_opcode;
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output reg [2:0] o_jump_length;
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output reg [3:0] o_instr_type;
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/* instruction is fully decoded */
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output reg [0:0] o_instr_decoded;
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@ -112,6 +116,12 @@ reg [0:0] decode_started;
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*/
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reg [0:0] block_2x;
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reg [0:0] block_6x;
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/*
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* temporary variables
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*/
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reg [2:0] jump_counter;
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/*
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* initialization
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@ -136,6 +146,10 @@ initial begin
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decode_started = 1'b0;
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block_2x = 1'b0;
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block_6x = 1'b0;
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/* local variables */
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jump_counter = 3'd0;
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end
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/****************************
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@ -161,7 +175,9 @@ always @(posedge i_clk) begin
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if (i_phases[1] && !decode_started) begin
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// $display("DECODER %0d: [%d] store current PC as instruction start %5h", i_phase, i_cycle_ctr, i_current_pc);
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o_instr_pc <= i_current_pc;
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o_instr_pc <= i_current_pc;
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/* set the instruction to NOP, to avoid any stray processes */
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o_instr_type <= `INSTR_TYPE_NOP;
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end
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if (i_phases[2] && !decode_started) begin
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@ -170,6 +186,15 @@ always @(posedge i_clk) begin
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decode_started <= 1'b1;
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case (i_nibble)
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4'h2: block_2x <= 1'b1;
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4'h6:
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begin
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o_instr_type <= `INSTR_TYPE_JUMP;
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o_jump_length <= 3'd2;
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jump_counter <= 3'd0;
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o_instr_execute <= 1'b1;
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block_6x <= 1'b1;
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end
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default: o_instr_type <= `INSTR_TYPE_NOP;
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endcase
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end
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@ -190,6 +215,16 @@ always @(posedge i_clk) begin
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decode_started <= 1'b0;
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end
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if (block_6x) begin
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// $display("DECODER %0d: [%d] GOTO %h", i_phase, i_cycle_ctr, i_nibble);
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jump_counter <= jump_counter + 3'd1;
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if (jump_counter == o_jump_length) begin
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block_6x <= 1'b0;
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o_instr_decoded <= 1'b1;
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decode_started <= 1'b0;
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end
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end
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end
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if (i_phases[3]) begin
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@ -221,6 +256,10 @@ always @(posedge i_clk) begin
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decode_started <= 1'b0;
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block_2x <= 1'b0;
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block_6x <= 1'b0;
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/* local variables */
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jump_counter = 3'd0;
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end
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end
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@ -31,6 +31,8 @@ module saturn_regs_pc_rstk (
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i_bus_busy,
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i_nibble,
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i_jump_instr,
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i_jump_length,
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o_current_pc
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@ -46,6 +48,8 @@ input wire [31:0] i_cycle_ctr;
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input wire [0:0] i_bus_busy;
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input wire [3:0] i_nibble;
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input wire [0:0] i_jump_instr;
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input wire [2:0] i_jump_length;
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output wire [19:0] o_current_pc;
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@ -55,19 +59,27 @@ output wire [19:0] o_current_pc;
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*
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*************************************************************************************************/
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wire [0:0] do_jump_instr = !just_reset && i_jump_instr;
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/*
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* local variables
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*/
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reg [0:0] just_reset;
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reg [0:0] jump_decode;
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reg [0:0] jump_exec;
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reg [2:0] jump_counter;
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reg [19:0] PC;
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assign o_current_pc = PC;
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initial begin
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just_reset = 1'b1;
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PC = 20'h00000;
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just_reset = 1'b1;
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jump_decode = 1'b0;
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jump_exec = 1'b0;
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jump_counter = 3'd0;
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PC = 20'h00000;
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end
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/*
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@ -95,11 +107,35 @@ always @(posedge i_clk) begin
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$display("PC_RSTK %0d: [%d] inc_pc %5h => %5h", i_phase, i_cycle_ctr, PC, PC + 20'h00001);
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PC <= PC + 20'h00001;
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end
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if (i_phases[2] && do_jump_instr && jump_decode) begin
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$display("PC_RSTK %0d: [%d] decode jump %0d - %0d %h", i_phase, i_cycle_ctr, i_jump_length, jump_counter, i_nibble);
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jump_counter <= jump_counter + 3'd1;
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if (jump_counter == i_jump_length) begin
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jump_decode <= 1'b0;
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jump_exec <= 1'b1;
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end
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end
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if (i_phases[3] && do_jump_instr && !jump_decode && !jump_exec) begin
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$display("PC_RSTK %0d: [%d] start decode jump %0d ", i_phase, i_cycle_ctr, i_jump_length);
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jump_counter <= 3'd0;
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jump_decode <= 1'b1;
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end
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if (i_phases[3] && do_jump_instr && jump_exec) begin
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$display("PC_RSTK %0d: [%d] execute jump %0d ", i_phase, i_cycle_ctr, i_jump_length);
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jump_exec <= 1'b0;
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end
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end
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if (i_reset) begin
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just_reset <= 1'b1;
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PC <= 20'h00000;
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just_reset <= 1'b1;
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jump_decode <= 1'b0;
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jump_exec <= 1'b0;
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jump_counter <= 3'd0;
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PC <= 20'h00000;
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end
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end
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