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-- Copyright 1991 Verdix Corporation

with system;				use system;
with unchecked_conversion;
package krn_cpu_defs is
	pragma suppress(ALL_CHECKS);
	pragma suppress(EXCEPTION_TABLES);
	pragma not_elaborated;

	-------------------------------------------------------------------------
	-- Kernel type definitions that are M68K cross target specific
	-------------------------------------------------------------------------

	-- Allocation and stack alignment
	ALIGNMENT: constant := 4;

	-- Size of exception stack frame for a trap instruction
	TRAP_FRAME_SIZE: constant := 8;

	-- This is to get around the problem with 'SIZE not working when
	-- the elaboration code doesn't get executed.
	storage_units_per_word: constant := 4;


	-- Note: for RTS performance reasons a6, a7 and pc aren't being
	-- updated. They're only there for the debugger.
	type cpu_state_t is record
		a6				:	address;	-- fp		-- 0
		a7				:	address;	-- sp		-- 4
		pc				:	address;				-- 8
		sr				:	short_integer;			-- c
		sr_pad			:	short_integer;

		-- When entered_from_intr = TRUE, restore_ssp points to
		-- preempted_state_t record pushed on the task's supervisor stack.
		-- The task's SSP is equal to the restore_ssp after this
		-- record has been popped from the stack. The restore_usp field
		-- contains the task's USP. None of the above registers
		-- are valid.
		--
		-- When entered_from_intr = 0, the above registers reflect
		-- the task's state upon entering the RTS.
		entered_from_intr		:	boolean;		-- 10
		entered_from_intr_pad1	:	tiny_integer;	-- 11
		entered_from_intr_pad2	:	short_integer;	-- 12
		restore_ssp				:	address;		-- 14
		restore_usp				:	address;		-- 18
		stack_limit				:   address;		-- 1c
	end record;
	for cpu_state_t'size use 16#20# * 8;
	type a_cpu_state_t is access cpu_state_t;

	-- Length of fields in krn_tcb_t record preceding cpu_state.
	cpu_state_offset:  constant := 0;
	-- CPU state record field offsets from beginning of task control
	-- block, not beginning of cpu_state
	a6_offset:			constant := cpu_state_offset + 16#00#;
	a7_offset:			constant := cpu_state_offset + 16#04#;
	pc_offset:			constant := cpu_state_offset + 16#08#;
	sr_offset:			constant := cpu_state_offset + 16#0C#;

	fp_offset:			constant := a6_offset;
	sp_offset:			constant := a7_offset;

	entered_from_intr_offset:	constant := cpu_state_offset + 16#10#;
	restore_ssp_offset: 		constant := cpu_state_offset + 16#14#;
	restore_usp_offset:			constant := cpu_state_offset + 16#18#;
	stack_limit_offset:			constant := cpu_state_offset + 16#1c#;


	--
	-- The following state is pushed on the current task's supervisor stack
	-- when the RTS is entered from an interrupt. For this case,
	-- ts.ct.proc_state.entered_from_intr = TRUE and 
	-- ts.ct.proc_state.restore_ssp points to this record on the stack.
	--
	type preempted_reg_t is array(0..14) of integer;	-- d0..d7, a0..a6
	type preempted_state_t is record
		preempted_reg	: preempted_reg_t;
		sr				: short_integer;
		pc				: integer;
	end record;
	pragma pack(preempted_state_t);
	for preempted_state_t'size use 8*32 + 7*32 + 16 + 32;
	type a_preempted_state_t is access preempted_state_t;

	--
	-- The following state is pushed on the current task's supervisor stack
	-- before doing a task switch. For this case,
	-- ts.ct.proc_state.entered_from_intr = FALSE and 
	-- ts.ct.proc_state.restore_ssp points to this record on the stack.
	--
	type switch_reg_t is array(0..8) of integer;	-- d4..d7, a2..a6
	type task_switch_state_t is record
		switch_reg		: switch_reg_t;
		pc				: integer;
	end record;
	pragma pack(task_switch_state_t);
	for task_switch_state_t'size use 4*32 + 5*32 + 32;
	type a_task_switch_state_t is access task_switch_state_t;

end krn_cpu_defs;

package body krn_cpu_defs is
end krn_cpu_defs