/*  GRT stack implementation for x86.
    Copyright (C) 2002, 2003, 2004, 2005 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.
*/
	.file		"i386.S"
	.version	"01.01"
	
	.text

#ifdef __ELF__
#define ENTRY(func) .align 4; .globl func; .type func,@function; func:
#define END(func) .size func, . - func
#define NAME(name) name
#elif __APPLE__
#define ENTRY(func) .align 4; .globl _##func; _##func:
#define END(func)
#define NAME(name) _##name
#else
#define ENTRY(func) .align 4; func:
#define END(func)
#define NAME(name) name
#endif
	
	/* Function called to loop on the process.  */
ENTRY(grt_stack_loop)
	call	*4(%esp)
	jmp	NAME(grt_stack_loop)
END(grt_stack_loop)

	/* function Stack_Create (Func : Address; Arg : Address)
 	                          return Stack_Type;
	*/
ENTRY(grt_stack_create)
	/* Standard prologue.  */
	pushl	%ebp
	movl	%esp,%ebp
	/* Keep aligned (call + pushl + 8 = 16 bytes).  */
	subl	$8,%esp
	
	/* Allocate the stack, and exit in case of failure  */
	call	NAME(grt_stack_allocate)
	testl	%eax,%eax
	je	.Ldone

	/* Note: %EAX contains the address of the stack_context.  This is
	   also the top of the stack.  */
				
	/* Prepare stack.  */
	/* The function to be executed.  */
	movl	8(%ebp), %ecx
	movl	%ecx, -4(%eax)
	/* The argument.  */
	movl	12(%ebp), %ecx
	movl	%ecx, -8(%eax)
	/* The return function.  */
	movl	$NAME(grt_stack_loop), -12(%eax)
	/* The context.  */
	movl	%ebx, -16(%eax)
	movl	%esi, -20(%eax)
	movl	%edi, -24(%eax)
	movl	%ebp, -28(%eax)

	/* Save the new stack pointer to the stack context.  */
	leal	-28(%eax), %ecx
	movl	%ecx, (%eax)

.Ldone:
	leave
	ret
END(grt_stack_create)


	/* Arguments:	TO, FROM
	   Both are pointers to a stack_context.  */
ENTRY(grt_stack_switch)
	/* TO -> ECX.  */
	movl	4(%esp), %ecx
	/* FROM -> EDX.  */
	movl	8(%esp), %edx
	/* Save call-used registers.  */
	pushl	%ebx
	pushl	%esi
	pushl	%edi
	pushl	%ebp
	/* Save the current stack.  */
	movl	%esp, (%edx)
	/* Stack switch.  */
	movl	(%ecx), %esp
	/* Restore call-used registers.  */
	popl	%ebp
	popl	%edi
	popl	%esi
	popl	%ebx
	/* Run.  */
	ret
END(grt_stack_switch)

	
	.ident	"Written by T.Gingold"