| Line 144... |
Line 144... |
reg pla;
|
reg pla;
|
reg plp;
|
reg plp;
|
reg jsr;
|
reg jsr;
|
reg tsx;
|
reg tsx;
|
reg txs;
|
reg txs;
|
|
reg nop;
|
|
|
wire [ADDR_SIZE_:0] next_pc; // a simple logic to add one to the PC
|
wire [ADDR_SIZE_:0] next_pc; // a simple logic to add one to the PC
|
assign next_pc = pc + 13'b0000000000001;
|
assign next_pc = pc + 13'b0000000000001;
|
|
|
wire [DATA_SIZE:0] sp_plus_one; // simple adder and subtracter for the stack pointer
|
wire [DATA_SIZE:0] sp_plus_one; // simple adder and subtracter for the stack pointer
|
| Line 605... |
Line 606... |
alu_enable = 1'b1;
|
alu_enable = 1'b1;
|
alu_a = temp_data;
|
alu_a = temp_data;
|
end
|
end
|
FETCH_LOW: begin
|
FETCH_LOW: begin
|
if (accumulator || implied || txs) begin
|
if (accumulator || implied || txs) begin
|
|
if (!nop) begin
|
alu_opcode = ir;
|
alu_opcode = ir;
|
alu_enable = 1'b1;
|
alu_enable = 1'b1;
|
|
end
|
next_state = FETCH_OP;
|
next_state = FETCH_OP;
|
end
|
end
|
else if (tsx) begin
|
else if (tsx) begin
|
alu_opcode = ir;
|
alu_opcode = ir;
|
alu_enable = 1'b1;
|
alu_enable = 1'b1;
|
| Line 897... |
Line 900... |
pla = 1'b0;
|
pla = 1'b0;
|
plp = 1'b0;
|
plp = 1'b0;
|
jsr = 1'b0;
|
jsr = 1'b0;
|
tsx = 1'b0;
|
tsx = 1'b0;
|
txs = 1'b0;
|
txs = 1'b0;
|
|
nop = 1'b0;
|
|
|
case (ir)
|
case (ir)
|
CLC_IMP, CLD_IMP, CLI_IMP, CLV_IMP, DEX_IMP, DEY_IMP, INX_IMP, INY_IMP, NOP_IMP,
|
CLC_IMP, CLD_IMP, CLI_IMP, CLV_IMP, DEX_IMP, DEY_IMP, INX_IMP, INY_IMP, SEC_IMP, SED_IMP, SEI_IMP, TAX_IMP,
|
SEC_IMP, SED_IMP, SEI_IMP, TAX_IMP, TAY_IMP, TXA_IMP, TYA_IMP: begin
|
TAY_IMP, TXA_IMP, TYA_IMP: begin
|
|
implied = 1'b1;
|
|
end
|
|
NOP_IMP: begin
|
implied = 1'b1;
|
implied = 1'b1;
|
|
nop = 1'b1;
|
end
|
end
|
ASL_ACC, LSR_ACC, ROL_ACC, ROR_ACC: begin
|
ASL_ACC, LSR_ACC, ROL_ACC, ROR_ACC: begin
|
accumulator = 1'b1;
|
accumulator = 1'b1;
|
end
|
end
|
ADC_IMM, AND_IMM, CMP_IMM, CPX_IMM, CPY_IMM, EOR_IMM, LDA_IMM, LDX_IMM, LDY_IMM, ORA_IMM, SBC_IMM: begin
|
ADC_IMM, AND_IMM, CMP_IMM, CPX_IMM, CPY_IMM, EOR_IMM, LDA_IMM, LDX_IMM, LDY_IMM, ORA_IMM, SBC_IMM: begin
|
