/*ident	"@(#)cop4:sparc_task/task/fudge.c.sparc	1.1" */
/*******************************************************************************
 
C++ source for the C++ Language System, Release 3.0.  This product
is a new release of the original cfront developed in the computer
science research center of AT&T Bell Laboratories.

Copyright (c) 1991 AT&T and UNIX System Laboratories, Inc.
Copyright (c) 1984, 1989, 1990 AT&T.  All Rights Reserved.

THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE of AT&T and UNIX System
Laboratories, Inc.  The copyright notice above does not evidence
any actual or intended publication of such source code.

*******************************************************************************/
/*
 * Copyright (c) 1990, 1991 by Sun Microsystems, Inc.
 */

#include <task.h>
#include "hw_stack.h"

// SPARC frame fudger
int*    Skip_pc_p;      // global to hold fudged return pc.
                        // See comments in hw_stack.c.


/* careful -- stack frame not self-describing */
// STACK GROWS DOWN

/*
 * On the SPARC, it's hopeless to try to guess how many of the
 * saved registers are meaningful.  But, they're always there and
 * the relevant parts of the stack layout never change.
 */
FrameLayout::FrameLayout(int* fp)
{
	int *ofp = (int*)OLD_FP(fp);

	FullFrameLen = ofp - fp;
}

/*
 * Fudge frame of function-defined-by-f_fp (called "f" below)
 * so that that function returns to its grandparent,
 * in particular, so a parent task returns to the function that
 * called the derived constructor (de_ctor), skipping de_ctor;
 * the child will return to the derived constructor, which is its "main."
 *
 * This will be quite different on the SPARC.
 *
 * Here's the first thing I think might work:
 *	SAVE
 *	FLUSH-REGS
 *	ALTER THE STACK CONNECTIONS
 *	RESTORE
 */
void
task::fudge_return(int* f_fp)
{
	int *p_fp, gramps_fp;

	// C gives me the SAVE
	asm("	t 0x83 ");

	// Now re-string the stack frames
	p_fp = (int*)OLD_FP(f_fp);
	gramps_fp = OLD_FP(p_fp);

	OLD_PC(f_fp) = OLD_PC(p_fp);
	OLD_FP(f_fp) = gramps_fp;
}