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Implement RLA and POP RR

This commit is contained in:
Koray Yanik 2022-02-08 23:53:02 +00:00
parent 4f892eb3f2
commit e713f8de87
9 changed files with 110 additions and 16 deletions
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2
build/tb_top.Makefile
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@ -1,5 +1,5 @@
TB = tb_top
SOURCES = gb.sv cpu.sv alu.sv registers.sv control.sv decode.sv rom.sv tb_top.sv clkgen.sv
SOURCES = gb.sv cpu.sv alu.sv registers.sv control.sv decode.sv rom.sv ram.sv tb_top.sv clkgen.sv
INCLUDES = cpu_pkg.svh
PATH_SRC = ../rtl:../rtl/cpu:../rtl/shared:../sim/tbench:../sim/shared

3
rtl/cpu/alu.sv
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@ -59,7 +59,8 @@ module alu (
assign a_next = (alu_op_valid_i & (alu_op_i == ALU_OP_XOR)) ? a_xor :
(alu_op_valid_i & (alu_op_i == ALU_OP_NOP)) ? operand_i :
(alu_op_valid_i & (alu_op_i == ALU_OP_INC)) ? a_inc :
a_r;
(alu_op_valid_i & (alu_op_i == ALU_OP_ROT) & (rot_op_i == ROT_OP_RL)) ? out8_rl :
a_r;
assign f_we = alu_op_valid_i | rot_op_valid_i;
assign f_next = (alu_op_valid_i & (alu_op_i == ALU_OP_XOR)) ? f_xor :

6
rtl/cpu/control.sv
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@ -75,6 +75,7 @@ module control (
logic decoder_need_instr1;
logic decoder_need_instr2;
logic decoder_is_multicycle;
logic decoder_is_multicycle2;
logic decoder_is_undef;
logic decoder_alu_op_valid;
logic decoder_rot_op_valid;
@ -144,8 +145,8 @@ module control (
ST2_DEC: state_next = decoder_need_instr2 ? ST3_DEC : ST3_EXEC;
ST3_DEC: state_next = ST4_EXEC;
ST3_EXEC: state_next = ST0_ADDR;
ST4_EXEC: state_next = decoder_is_multicycle ? ST5_EXEC : ST0_ADDR;
ST3_EXEC: state_next = decoder_is_multicycle2 ? ST4_EXEC : ST0_ADDR;
ST4_EXEC: state_next = decoder_need_instr2 & decoder_is_multicycle ? ST5_EXEC : ST0_ADDR;
ST5_EXEC: state_next = ST0_ADDR;
endcase
end
@ -159,6 +160,7 @@ module control (
.need_instr1_o (decoder_need_instr1),
.need_instr2_o (decoder_need_instr2),
.is_multicycle_o(decoder_is_multicycle),
.is_multicycle2_o(decoder_is_multicycle2),
.undef_o (decoder_is_undef),
.sp_we_o (decoder_sp_we),

5
rtl/cpu/cpu.sv
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@ -32,6 +32,8 @@ module cpu (
logic [15:0] sp;
logic [15:0] hl;
logic [15:0] sp_p1;
logic instr_valid;
logic instr_undef;
@ -119,6 +121,8 @@ module cpu (
.hl_o (hl)
);
assign sp_p1 = (sp + 16'h01);
assign alu_operand = (op_src == OP_SRC_A) ? rega :
(op_src == OP_SRC_F) ? regf :
(op_src == OP_SRC_OPERAND8) ? operand8 :
@ -136,6 +140,7 @@ module cpu (
assign address_o = (adr_src == ADR_SRC_HL) ? hl :
(adr_src == ADR_SRC_SP) ? sp :
(adr_src == ADR_SRC_SP_P1) ? sp_p1 :
(adr_src == ADR_SRC_REG8) ? {8'hFF, reg8_rdata} :
(adr_src == ADR_SRC_REG16) ? reg16_rdata :
(adr_src == ADR_SRC_OPERAND8) ? {8'hFF, operand8} :

9
rtl/cpu/cpu_pkg.svh
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@ -50,9 +50,11 @@ package cpu_pkg;
ALU_OP_OR = 5'h06,
ALU_OP_CP = 5'h07,
ALU_OP_BIT = 5'h08,
ALU_OP_NOP = 5'h09,
ALU_OP_INC = 5'h10,
ALU_OP_INCR = 5'h11 // Increment register instead of a
ALU_OP_NOP = 5'h09, // Write operand to a
ALU_OP_NOPF = 5'h0a, // Write operand to f
ALU_OP_ROT = 5'h0b,
ALU_OP_INC = 5'h0c,
ALU_OP_INCR = 5'h0d // Increment register instead of a
} alu_op_t;
typedef enum logic [2:0] {
@ -101,6 +103,7 @@ package cpu_pkg;
ADR_SRC_PC,
ADR_SRC_HL,
ADR_SRC_SP,
ADR_SRC_SP_P1, // SP + 1 for pop
ADR_SRC_REG8, // extended with FF
ADR_SRC_REG16,
ADR_SRC_OPERAND8, // extended with FF

34
rtl/cpu/decode.sv
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@ -12,6 +12,7 @@ module decode (
output logic need_instr1_o,
output logic need_instr2_o,
output logic is_multicycle_o,
output logic is_multicycle2_o,
output logic undef_o,
output logic sp_we_o,
@ -61,11 +62,13 @@ module decode (
logic is_alu_a_r;
logic is_bit_n_r;
logic is_rot_r;
logic is_rla;
logic is_inc_a;
logic is_inc_r;
logic is_jr_cc_n;
logic is_call_nn;
logic is_push_rr;
logic is_pop_rr;
reg8_t reg8_dest;
reg8_t reg8_src;
@ -96,12 +99,15 @@ module decode (
assign is_bit_n_r = (is_cb & instr1_i[7:6] == 2'h1);
assign is_rot_r = (is_cb & instr1_i[7:6] == 2'h0);
assign is_rla = (dec_x == 3'h0) & (dec_z == 3'h7) & (dec_y == 3'h2);
assign is_inc_a = is_inc_r & (reg8_dest == REG8_A);
assign is_inc_r = (dec_x == 2'h0) & (dec_z == 3'h4);
assign is_jr_cc_n = (dec_x == 2'h0) & (dec_z == 2'h0) & dec_y[2];
assign is_call_nn = (instr0_i == 8'hCD);
assign is_push_rr = (dec_x == 2'h3) & (dec_z == 3'h5) && ~dec_q;
assign is_push_rr = (dec_x == 2'h3) & (dec_z == 3'h5) & ~dec_q;
assign is_pop_rr = (dec_x == 2'h3) & (dec_z == 3'h1) & ~dec_q;
assign reg8_src = is_cb ? reg8_t'(instr1_i[2:0]) :
is_ldh_c_a ? REG8_C :
@ -110,36 +116,44 @@ module decode (
(is_push_rr & state_i == ST3_EXEC) ? reg8_t'({dec_p, 1'b1}) :
reg8_t'(dec_z);
assign reg8_dest = is_rot_r ? reg8_t'(dec_z) :
(is_pop_rr & state_i == ST3_EXEC) ? reg8_t'({dec_p, 1'b1}) :
(is_pop_rr & state_i == ST4_EXEC) ? reg8_t'({dec_p, 1'b0}) :
reg8_t'(dec_y);
assign reg16_src = is_ldd_hl_a ? REG16_HL : reg16_t'(dec_p);
assign need_instr1_o = is_ld_sp_nn | is_ld_rr_nn | is_ld_a_nn | is_call_nn | is_cb | is_jr_cc_n | is_ld_r_n | is_ldh_n_a;
assign need_instr2_o = is_ld_sp_nn | is_ld_rr_nn | is_ld_a_nn | is_call_nn;
assign is_multicycle_o = is_ld_a_rr | is_call_nn | is_push_rr;
assign is_multicycle_o = is_ld_a_rr | is_call_nn | is_push_rr | is_pop_rr;
assign is_multicycle2_o = is_pop_rr;
assign undef_o = ~(is_ldh_n_a | is_ld_r_r | is_ld_sp_nn | is_ld_rr_nn | is_alu_a_r | is_ldd_hl_a | is_bit_n_r |
is_jr_cc_n | is_ld_r_n | is_ldh_c_a | is_inc_r | is_ld_rr_a | is_ld_a_rr | is_call_nn |
is_push_rr | (is_rot_r & (instr1_i[5:3] == 3'h02)));
is_push_rr | is_pop_rr | (is_rot_r & (instr1_i[5:3] == 3'h02)) | is_rla);
assign sp_we_o = is_ld_sp_nn | is_call_nn | is_push_rr;
assign sp_we_o = is_ld_sp_nn | is_call_nn | is_push_rr | (is_pop_rr & ((state_i == ST2_EXEC) | (state_i == ST3_EXEC)));
assign sp_src_o = is_ld_sp_nn ? SP_SRC_OPERAND16 :
is_call_nn ? SP_SRC_DEC :
is_push_rr ? SP_SRC_DEC :
is_pop_rr ? SP_SRC_INC :
sp_src_t'('X);
assign alu_op_valid_o = is_alu_a_r | is_bit_n_r | is_ld_a_n | is_ld_a_rr | is_ld_a_nn | is_inc_r;
assign alu_op_valid_o = is_alu_a_r | is_bit_n_r | is_ld_a_n | is_ld_a_rr | is_ld_a_nn | is_inc_r | is_rla | (is_pop_rr & reg16_src == REG16_SP_AF);
assign alu_op_o = is_bit_n_r ? ALU_OP_BIT :
is_ld_a_n ? ALU_OP_NOP :
is_ld_a_nn ? ALU_OP_NOP :
is_ld_a_rr ? ALU_OP_NOP :
is_inc_a ? ALU_OP_INC :
is_inc_r ? ALU_OP_INCR :
is_rla ? ALU_OP_ROT :
(is_pop_rr & reg16_src == REG16_SP_AF & state_i == ST2_EXEC) ? ALU_OP_NOP :
(is_pop_rr & reg16_src == REG16_SP_AF & state_i == ST3_EXEC) ? ALU_OP_NOPF :
alu_op_t'({1'b0, dec_y});
assign reg_write_alu_o = is_inc_r | is_rot_r;
assign rot_op_valid_o = is_rot_r;
assign rot_op_o = rot_op_t'(instr1_i[5:3]);
assign rot_op_valid_o = is_rot_r | is_rla;
assign rot_op_o = is_rla ? ROT_OP_RL :
rot_op_t'(instr1_i[5:3]);
assign op_dest_o = (is_ld_r_r & reg8_dest == REG8_PHL) ? OP_DEST_MEMORY :
(is_ld_r_n & reg8_dest == REG8_PHL) ? OP_DEST_MEMORY :
@ -157,7 +171,10 @@ module decode (
is_inc_r ? OP_DEST_REG8 :
is_call_nn ? OP_DEST_MEMORY :
is_push_rr ? OP_DEST_MEMORY :
(is_pop_rr & reg16_src != REG16_SP_AF) ? OP_DEST_REG8 :
(is_pop_rr & reg16_src == REG16_SP_AF) ? OP_DEST_A :
is_rot_r ? OP_DEST_REG8 :
is_rla ? OP_DEST_A :
op_dest_t'('X);
assign op_src_o = (is_ld_r_r & reg8_src == REG8_A) ? OP_SRC_A :
@ -174,11 +191,13 @@ module decode (
is_ldd_hl_a ? OP_SRC_REG16 :
is_bit_n_r ? OP_SRC_REG8 :
is_rot_r ? OP_SRC_REG8 :
is_rla ? OP_SRC_A :
(is_call_nn & state_i == ST4_EXEC) ? OP_SRC_PC_L :
(is_call_nn & state_i == ST5_EXEC) ? OP_SRC_PC_H :
(is_push_rr & reg16_src != REG16_SP_AF) ? OP_SRC_REG8 :
(is_push_rr & reg16_src == REG16_SP_AF & state_i == ST2_EXEC) ? OP_SRC_A :
(is_push_rr & reg16_src == REG16_SP_AF & state_i == ST3_EXEC) ? OP_SRC_F :
is_pop_rr ? OP_SRC_MEMORY :
op_src_t'('X);
assign reg8_dest_o = reg8_dest;
@ -202,6 +221,7 @@ module decode (
is_ld_rr_a ? ADR_SRC_REG16 :
is_call_nn ? ADR_SRC_SP :
is_push_rr ? ADR_SRC_SP :
is_pop_rr ? ADR_SRC_SP_P1 :
ADR_SRC_PC;
assign branch_always_o = is_call_nn;

26
rtl/gb.sv
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@ -8,6 +8,12 @@ module gb (
logic [ 7:0] rdata;
logic [ 7:0] wdata;
logic rom_cs;
logic [ 7:0] rom_rdata;
logic hi_ram_cs;
logic [ 7:0] hi_ram_rdata;
cpu cpu_inst (
.clk_i (clk_i),
.nreset_i (nreset_i),
@ -23,8 +29,26 @@ module gb (
.DATA_W (8)
) rom_inst (
.clk_i (clk_i),
.cs_i (rom_cs),
.address_i(address[7:0]),
.rdata_o (rdata)
.rdata_o (rom_rdata)
);
ram #(
.ADDR_W (7),
.DATA_W (8)
) hi_ram_inst (
.clk_i (clk_i),
.cs_i (hi_ram_cs),
.address_i (address[6:0]),
.rdata_o (hi_ram_rdata),
.we_i (we),
.wdata_i (wdata)
);
assign rom_cs = ~(|address[15:8]);
assign hi_ram_cs = (&address[15:7]) & ~(&address[6:0]);
assign rdata = rom_rdata | hi_ram_rdata;
endmodule : gb

34
rtl/shared/ram.sv Normal file
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@ -0,0 +1,34 @@
module ram #(
parameter DATA_W = 8,
parameter ADDR_W = 8
)(
input logic clk_i,
input logic cs_i,
input logic [ADDR_W-1:0] address_i,
input logic we_i,
input logic [DATA_W-1:0] wdata_i,
output logic [DATA_W-1:0] rdata_o
);
localparam RAM_SIZE = 2**ADDR_W;
logic [DATA_W-1:0] ram [RAM_SIZE-1:0];
logic wenable;
logic [DATA_W-1:0] rdata;
assign wenable = cs_i & we_i;
always_ff @(posedge clk_i)
if (wenable)
ram[address_i] <= wdata_i;
always_ff @(posedge clk_i)
if (cs_i)
rdata <= ram[address_i];
assign rdata_o = {DATA_W{cs_i}} & rdata;
endmodule

7
rtl/shared/rom.sv
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@ -4,6 +4,7 @@ module rom #(
parameter integer unsigned DATA_W = 8
) (
input logic clk_i,
input logic cs_i,
input logic [ADDR_W-1:0] address_i,
output logic [DATA_W-1:0] rdata_o
@ -12,9 +13,13 @@ module rom #(
localparam ROM_SIZE = 2**ADDR_W;
logic [DATA_W-1:0] rom [ROM_SIZE-1:0];
logic [DATA_W-1:0] rdata;
always_ff @(posedge clk_i)
rdata_o <= rom[address_i];
if (cs_i)
rdata <= rom[address_i];
assign rdata_o = {DATA_W{cs_i}} & rdata;
initial begin
static integer fd = $fopen(FILE_NAME, "rb");