📄 cpu01.vhd
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next_state <= fetch_state;
end if;
when "0100" => -- bcc/bhs
if cc(CBIT) = '0' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "0101" => -- bcs/blo
if cc(CBIT) = '1' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "0110" => -- bne
if cc(ZBIT) = '0' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "0111" => -- beq
if cc(ZBIT) = '1' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1000" => -- bvc
if cc(VBIT) = '0' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1001" => -- bvs
if cc(VBIT) = '1' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1010" => -- bpl
if cc(NBIT) = '0' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1011" => -- bmi
if cc(NBIT) = '1' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1100" => -- bge
if (cc(NBIT) xor cc(VBIT)) = '0' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1101" => -- blt
if (cc(NBIT) xor cc(VBIT)) = '1' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1110" => -- bgt
if (cc(ZBIT) or (cc(NBIT) xor cc(VBIT))) = '0' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when "1111" => -- ble
if (cc(ZBIT) or (cc(NBIT) xor cc(VBIT))) = '1' then
next_state <= branch_state;
else
next_state <= fetch_state;
end if;
when others =>
next_state <= fetch_state;
end case;
--
-- Single byte stack operators
-- Do not advance PC
--
when "0011" =>
md_ctrl <= fetch_first_md;
acca_ctrl <= latch_acca;
accb_ctrl <= latch_accb;
pc_ctrl <= latch_pc;
case op_code(3 downto 0) is
when "0000" => -- tsx
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= load_ix;
sp_ctrl <= latch_sp;
next_state <= fetch_state;
when "0001" => -- ins
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= fetch_state;
when "0010" => -- pula
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= pula_state;
when "0011" => -- pulb
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= pulb_state;
when "0100" => -- des
-- decrement sp
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_sub16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= fetch_state;
when "0101" => -- txs
left_ctrl <= ix_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_sub16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= fetch_state;
when "0110" => -- psha
left_ctrl <= sp_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= psha_state;
when "0111" => -- pshb
left_ctrl <= sp_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= pshb_state;
when "1000" => -- pulx
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= pulx_hi_state;
when "1001" => -- rts
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= rts_hi_state;
when "1010" => -- abx
left_ctrl <= ix_left;
right_ctrl <= accb_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= load_ix;
sp_ctrl <= latch_sp;
next_state <= fetch_state;
when "1011" => -- rti
left_ctrl <= sp_left;
right_ctrl <= plus_one_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= load_sp;
next_state <= rti_cc_state;
when "1100" => -- pshx
left_ctrl <= sp_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= pshx_lo_state;
when "1101" => -- mul
left_ctrl <= acca_left;
right_ctrl <= accb_right;
alu_ctrl <= alu_add16;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= mul_state;
when "1110" => -- wai
left_ctrl <= sp_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= int_pcl_state;
when "1111" => -- swi
left_ctrl <= sp_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= int_pcl_state;
when others =>
left_ctrl <= sp_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
next_state <= fetch_state;
end case;
--
-- Accumulator A Single operand
-- source = Acc A dest = Acc A
-- Do not advance PC
--
when "0100" => -- acca single op
md_ctrl <= fetch_first_md;
accb_ctrl <= latch_accb;
pc_ctrl <= latch_pc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
left_ctrl <= acca_left;
case op_code(3 downto 0) is
when "0000" => -- neg
right_ctrl <= zero_right;
alu_ctrl <= alu_neg;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "0011" => -- com
right_ctrl <= zero_right;
alu_ctrl <= alu_com;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "0100" => -- lsr
right_ctrl <= zero_right;
alu_ctrl <= alu_lsr8;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "0110" => -- ror
right_ctrl <= zero_right;
alu_ctrl <= alu_ror8;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "0111" => -- asr
right_ctrl <= zero_right;
alu_ctrl <= alu_asr8;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "1000" => -- asl
right_ctrl <= zero_right;
alu_ctrl <= alu_asl8;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "1001" => -- rol
right_ctrl <= zero_right;
alu_ctrl <= alu_rol8;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "1010" => -- dec
right_ctrl <= plus_one_right;
alu_ctrl <= alu_dec;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "1011" => -- undefined
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
acca_ctrl <= latch_acca;
cc_ctrl <= latch_cc;
when "1100" => -- inc
right_ctrl <= plus_one_right;
alu_ctrl <= alu_inc;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when "1101" => -- tst
right_ctrl <= zero_right;
alu_ctrl <= alu_st8;
acca_ctrl <= latch_acca;
cc_ctrl <= load_cc;
when "1110" => -- jmp
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
acca_ctrl <= latch_acca;
cc_ctrl <= latch_cc;
when "1111" => -- clr
right_ctrl <= zero_right;
alu_ctrl <= alu_clr;
acca_ctrl <= load_acca;
cc_ctrl <= load_cc;
when others =>
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
acca_ctrl <= latch_acca;
cc_ctrl <= latch_cc;
end case;
next_state <= fetch_state;
--
-- single operand acc b
-- Do not advance PC
--
when "0101" =>
md_ctrl <= fetch_first_md;
acca_ctrl <= latch_acca;
pc_ctrl <= latch_pc;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
left_ctrl <= accb_left;
case op_code(3 downto 0) is
when "0000" => -- neg
right_ctrl <= zero_right;
alu_ctrl <= alu_neg;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "0011" => -- com
right_ctrl <= zero_right;
alu_ctrl <= alu_com;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "0100" => -- lsr
right_ctrl <= zero_right;
alu_ctrl <= alu_lsr8;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "0110" => -- ror
right_ctrl <= zero_right;
alu_ctrl <= alu_ror8;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "0111" => -- asr
right_ctrl <= zero_right;
alu_ctrl <= alu_asr8;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "1000" => -- asl
right_ctrl <= zero_right;
alu_ctrl <= alu_asl8;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "1001" => -- rol
right_ctrl <= zero_right;
alu_ctrl <= alu_rol8;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "1010" => -- dec
right_ctrl <= plus_one_right;
alu_ctrl <= alu_dec;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "1011" => -- undefined
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
accb_ctrl <= latch_accb;
cc_ctrl <= latch_cc;
when "1100" => -- inc
right_ctrl <= plus_one_right;
alu_ctrl <= alu_inc;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when "1101" => -- tst
right_ctrl <= zero_right;
alu_ctrl <= alu_st8;
accb_ctrl <= latch_accb;
cc_ctrl <= load_cc;
when "1110" => -- jmp
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
accb_ctrl <= latch_accb;
cc_ctrl <= latch_cc;
when "1111" => -- clr
right_ctrl <= zero_right;
alu_ctrl <= alu_clr;
accb_ctrl <= load_accb;
cc_ctrl <= load_cc;
when others =>
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
accb_ctrl <= latch_accb;
cc_ctrl <= latch_cc;
end case;
next_state <= fetch_state;
--
-- Single operand indexed
-- Two byte instruction so advance PC
-- EA should hold index offset
--
when "0110" => -- indexed single op
md_ctrl <= fetch_first_md;
acca_ctrl <= latch_acca;
accb_ctrl <= latch_accb;
ix_ctrl <= latch_ix;
sp_ctrl <= latch_sp;
-- increment the pc
left_ctrl <= acca_left;
right_ctrl <= zero_right;
alu_ctrl <= alu_nop;
cc_ctrl <= latch_cc;
pc_ctrl <= inc_pc;
next_state <= i⌨️ 快捷键说明
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