microroutines.txt

when fetch_inst_0 =>
	-- Fetch the instruction at PC
	cs.m.op := Read;
	cs.m.addr := PC;

when fetch_inst_1 =>
	-- Remember to enable the latch register
	cs.m.regce := '1';

when fetch_inst_2 =>
	-- Update PC to point to next instruction
	cs.r.pc.op := LoadNextInstructionAddress;
	
	-- Jump to corresponding microroutine
	cs.uc.op := ExecInstruction;



when inst_lxi_0 =>
	-- We need to load the two data byte operands.
	-- The low byte is pc-2, and high byte is pc-1.
	cs.m.op := Read;
	
	cs.m.addr := PC;
	cs.m.addr_offset := -2;
	
when inst_lxi_1 =>
	-- Register for low byte
	cs.m.regce := '1';

when inst_lxi_2 =>
	-- Load low byte into low register
	set_register_ce_LXI_lo(inst_reg, cs.r);

when inst_lxi_3 =>
	-- Now we need high byte.
	-- Issue read instruction for high byte
	cs.m.op := Read;
	
	cs.m.addr := PC;
	cs.m.addr_offset := -1;
	
when inst_lxi_4 =>
	-- Register for high byte
	cs.m.regce := '1';

when inst_lxi_5 =>
	-- Load high byte into high register
	set_register_ce_LXI_hi(inst_reg, cs.r);

	-- Fetch next instruction
	cs.uc.op := FetchInstruction;

when others =>
	nul;

end case;