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implement PC related functionnality, relative and absolute jumps

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This commit is contained in:
Raphael Jacquot 2019-02-22 12:00:23 +01:00
parent 93d786c2c1
commit 2028715939
2 changed files with 109 additions and 19 deletions
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126
saturn_alu.v
View file

@ -226,14 +226,6 @@ reg alu_run;
reg alu_done;
reg alu_go_test;
/*
* next PC in case of jump
*/
reg [19:0] jump_bse;
reg [19:0] jump_off;
wire [19:0] jump_pc;
assign jump_pc = (alu_op == `ALU_OP_JMP_ABS5)?jump_off:(jump_bse + jump_off);
reg [2:0] rstk_ptr;
/* public registers */
@ -478,10 +470,14 @@ always @(posedge i_clk) begin
*/
if (start_in_jmp_mode) begin
$display("ALU %0d: [%d] jmp mode started (i_ins_decoded %b)", phase, i_cycle_ctr, i_ins_decoded);
$display("ALU %0d: [%d] stall the decoder",phase, i_cycle_ctr);
f_mode_jmp <= 1;
end
if (do_apply_jump) begin
$display("ALU %0d: [%d] end of jmp mode", phase, i_cycle_ctr);
f_mode_jmp <= 0;
end
/* general ALU mode (when there is no optimization)
*/
if (start_in_alu_mode) begin
@ -536,7 +532,6 @@ wire [0:0] copy_address;
wire [0:0] start_load_dp;
wire mode_xfr;
assign mode_xfr = start_in_xfr_mode || f_mode_xfr;
assign addr_src_A = (!mode_xfr) && src1_A;
@ -858,16 +853,84 @@ end
// assign push_pc = update_pc && i_push && alu_finish;
/* jump values generator */
wire mode_jmp;
assign mode_jmp = start_in_jmp_mode || f_mode_jmp;
reg [2:0] jump_offset_counter;
reg [19:0] jump_base;
reg [19:0] jump_offset;
wire [0:0] jump_counter_0;
wire [0:0] jump_counter_1;
wire [0:0] jump_counter_2;
wire [0:0] jump_counter_3;
wire [0:0] jump_counter_4;
assign jump_counter_0 = (jump_offset_counter == 0);
assign jump_counter_1 = (jump_offset_counter == 1);
assign jump_counter_2 = (jump_offset_counter == 2);
assign jump_counter_3 = (jump_offset_counter == 3);
assign jump_counter_4 = (jump_offset_counter == 4);
wire [19:0] jump_offset_1;
wire [19:0] jump_offset_2;
wire [19:0] jump_offset_3;
wire [19:0] jump_offset_4;
wire [19:0] jump_offset_5;
assign jump_offset_1 = {{16{i_bus_nibble_in[3] && jump_relative}}, i_imm_value};
assign jump_offset_2 = {{12{i_bus_nibble_in[3] && jump_relative}}, i_imm_value, jump_offset[ 3:0]};
assign jump_offset_3 = {{ 8{i_bus_nibble_in[3] && jump_relative}}, i_imm_value, jump_offset[ 7:0]};
assign jump_offset_4 = {{ 4{i_bus_nibble_in[3] && jump_relative}}, i_imm_value, jump_offset[11:0]};
assign jump_offset_5 = { i_imm_value, jump_offset[15:0]};
wire [19:0] new_jump_offset;
assign new_jump_offset = ({20{jump_counter_0}} & jump_offset_1) |
({20{jump_counter_1}} & jump_offset_2) |
({20{jump_counter_2}} & jump_offset_3) |
({20{jump_counter_3}} & jump_offset_4) |
({20{jump_counter_4}} & jump_offset_5);
wire [0:0] jump_rel_2_done;
wire [0:0] jump_rel_3_done;
wire [0:0] jump_rel_4_done;
wire [0:0] jump_abs_5_done;
wire [0:0] jump_done;
assign jump_rel_2_done = jump_counter_1 && op_jmp_rel_2;
assign jump_rel_3_done = jump_counter_2 && op_jmp_rel_3;
assign jump_rel_4_done = jump_counter_3 && op_jmp_rel_4;
assign jump_abs_5_done = jump_counter_4 && op_jmp_abs_5;
assign jump_done = jump_rel_2_done || jump_rel_3_done || jump_rel_4_done || jump_abs_5_done;
wire [0:0] do_set_jump_base;
wire [0:0] do_calc_jump;
wire [0:0] do_apply_jump;
assign do_set_jump_base = start_in_jmp_mode && !jump_done && jump_counter_0;
assign do_calc_jump = mode_jmp && phase_3 && !jump_done;
assign do_apply_jump = mode_jmp && phase_3 && jump_done;
wire [0:0] jump_relative;
assign jump_relative = op_jmp_rel_2 || op_jmp_rel_3 || op_jmp_rel_4;
wire [19:0] jump_pc;
assign jump_pc = jump_relative?(jump_base+new_jump_offset):new_jump_offset;
/* pc update generator */
wire [19:0] next_pc;
wire [0:0] update_pc;
wire [0:0] reload_pc;
wire [0:0] pop_pc;
wire [0:0] pc_lines_cleanup;
assign next_pc = /*(set_unc_jmp || set_jmp_rel2)?jump_pc:*/PC + 1;
assign update_pc = (!i_reset && just_reset) /*!o_alu_stall_dec || exec_unc_jmp || exec_jmp_rel2 */;
assign next_pc = (jump_done)?jump_pc:PC + 1;
assign update_pc = (!i_reset && just_reset) || alu_active && phase_3 && (!o_alu_stall_dec) /* || exec_unc_jmp || exec_jmp_rel2 */;
assign pop_pc = i_pop && i_ins_rtn && ((!i_ins_test_go) || (i_ins_test_go && CARRY));
assign reload_pc = (!i_reset && just_reset) /*|| (exec_unc_jmp || pop_pc || exec_jmp_rel2)*/;
assign reload_pc = (!i_reset && just_reset) || do_apply_jump;
assign pc_lines_cleanup = alu_active && phase_0;
@ -877,9 +940,12 @@ always @(posedge i_clk) begin
* initializes default values
*/
if (i_reset) begin
PC <= ~0;
o_bus_load_pc <= 0;
rstk_ptr <= 0;
PC <= ~0;
o_bus_load_pc <= 0;
rstk_ptr <= 0;
jump_offset_counter <= 0;
jump_base <= 0;
jump_offset <= 0;
end
/*
@ -890,6 +956,30 @@ always @(posedge i_clk) begin
if (alu_initializing)
RSTK[v_dest_counter_ptr] <= 0;
/**
* handles jumps
*
*/
if (do_set_jump_base) begin
// $display("ALU_PC %0d: [%d] set jump base %0d | nibble %h | rel %b | base %h | offset %h | jump_pc %h",
// phase, i_cycle_ctr, jump_offset_counter, i_imm_value, jump_relative, PC, new_jump_offset, jump_pc);
jump_base <= PC;
end
if (do_calc_jump) begin
// $display("ALU_PC %0d: [%d] calc jump %0d | nibble %h | rel %b | base %h | offset %h | jump_pc %h",
// phase, i_cycle_ctr, jump_offset_counter, i_imm_value, jump_relative, jump_base, new_jump_offset, jump_pc);
jump_offset <= new_jump_offset;
jump_offset_counter <= jump_offset_counter + 1;
end
if (do_apply_jump) begin
// $display("ALU_PC %0d: [%d] apply jump %0d | nibble %h | rel %b | base %h | offset %h | jump_pc %h",
// phase, i_cycle_ctr, jump_offset_counter, i_imm_value, jump_relative, jump_base, new_jump_offset, jump_pc);
jump_offset_counter <= 0;
end
/**
*
* Update the PC.
@ -899,12 +989,12 @@ always @(posedge i_clk) begin
*/
if (update_pc) begin
$display("ALU_PC %0d: [%d] update pc to %h", phase, i_cycle_ctr, next_pc);
// $display("ALU_PC %0d: [%d] update pc to %h", phase, i_cycle_ctr, next_pc);
PC <= /*pop_pc ? RSTK[rstk_ptr - 1] : */next_pc;
end
if (reload_pc) begin
$display("ALU_PC %0d: [%d] $$$$ RELOADING PC to %h $$$$", phase, i_cycle_ctr, next_pc);
// $display("ALU_PC %0d: [%d] $$$$ RELOADING PC to %h $$$$", phase, i_cycle_ctr, next_pc);
o_bus_address <= pop_pc ? RSTK[rstk_ptr-1] : next_pc;
o_bus_load_pc <= 1;
end

2
saturn_bus_ctrl.v
View file

@ -700,7 +700,7 @@ always @(posedge i_clk) begin
if (do_run_addr_loop) begin
$write("BUS_CTRL %1d: [%d] ADDR(%0d)-> %h ",
i_phase, i_cycle_ctr, o_data_ptr,
i_data_nibl);
LC_load_pc?i_address[o_data_ptr*4+:4]:i_data_nibl);
if (will_loop_finish) $write("done");
$write("\n");