/*  GRT stack implementation for x86.
    Copyright (C) 2002 - 2014 Tristan Gingold.

    GHDL is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2, or (at your option) any later
    version.

    GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with GCC; see the file COPYING.  If not, write to the Free
    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
    02111-1307, USA.

    As a special exception, if other files instantiate generics from this
    unit, or you link this unit with other files to produce an executable,
    this unit does not by itself cause the resulting executable to be
    covered by the GNU General Public License. This exception does not
    however invalidate any other reasons why the executable file might be
    covered by the GNU Public License.
*/
	.file		"sparc.S"
	
	.section	".text"

	/* Stack structure is:
           +4 :	cur_length
	   +0 :	cur_sp
	   -4 :	return address
	   -8 :	process function to be executed
           -12:	function argument
	   ...
           -72:	%sp
	*/
	
	/* Function called to loop on the process.  */	
	.align 4
	.type	grt_stack_loop,#function
grt_stack_loop:
	ld	[%sp + 64], %o1
	jmpl	%o1 + 0, %o7
	ld	[%sp + 68], %o0
	ba	grt_stack_loop
	nop
	.size	grt_stack_loop, . - grt_stack_loop

	/* function Stack_Create (Func : Address; Arg : Address)
	                         return Stack_Type;  */
	.align	4
	.global grt_stack_create
	.type	 grt_stack_create,#function
grt_stack_create:
	/* Standard prologue.  */
	save	%sp,-80,%sp
	
	/* Allocate the stack, and exit in case of failure  */
	call	grt_stack_allocate
	nop
	cmp	%o0, 0
	be	.Ldone
	nop

	/* Note: %o0 contains the address of the stack_context.  This is
	   also the top of the stack.  */
				
	/* Prepare stack.  */

	/* The return function.  */
	sethi	%hi(grt_stack_loop - 8), %l2
	or	%lo(grt_stack_loop - 8), %l2, %l2

	/* Create a frame for grt_stack_loop. */
	sub	%o0, (64 + 8), %l1

	/* The function to be executed.  */
	st	%i0, [%l1 + 64]
	/* The argument.  */
	st	%i1, [%l1 + 68]

	/* Create a frame for grt_stack_switch.  */
	sub	%l1, 64, %l0

	/* Save frame pointer.  */
	st	%l1, [%l0 + 56]
	/* Save return address.  */
	st	%l2, [%l0 + 60]

	/* Save stack pointer.  */
	st	%l0, [%o0]

.Ldone:
	ret
	restore %o0, %g0, %o0
	.size	 grt_stack_create,. - grt_stack_create


	.align 4
	.global grt_stack_switch
	/* Arguments:	TO, FROM.
	   Both are pointers to a stack_context.  */
	.type	 grt_stack_switch,#function
grt_stack_switch:
	/* Standard prologue.  */
	save	%sp,-80,%sp

	/* Flush and invalidate windows.
	   It is not clear wether the current window is saved or not,
	    therefore, I assume it is not.
	*/
	ta	3

	/* Only IN registers %fp and %i7 (return address) must be saved.
	   Of course, I could use std/ldd, but it is not as clear
	*/
	/* Save current frame pointer.  */
	st	%fp, [%sp + 56]
	/* Save return address.  */
	st	%i7, [%sp + 60]

	/* Save stack pointer.  */
	st	%sp, [%i1]

	/* Load stack pointer.  */
	ld	[%i0], %sp
	
	/* Load return address.  */
	ld	[%sp + 60], %i7
	/* Load frame pointer.  */
	ld	[%sp + 56], %fp

	/* Return.  */
	ret
	restore	
	.size	 grt_stack_switch, . - grt_stack_switch

	
	.ident	"Written by T.Gingold"