/*	$OpenBSD: uthread_machdep_asm.S,v 1.1 2001/09/10 20:00:14 jason Exp $	*/
/* David Leonard <d@csee.uq.edu.au>. Public domain. */

#include <machine/asm.h>
#include <machine/trap.h>

/*
 * Switch stacks.
 * On sparc this also means we switch register windows.
 */

#ifdef __sparcv9__
#define flushw		.word 0x81580000
#else
#define flushw		t T_FLUSHWIN
#endif

#define SA(x)	(((x)+15)&(~0x1f))
#define MINFRAME ((16+1+6)*8)	

/* void _thread_switch(int newstate[2], int savestate[2], int flags); */
ENTRY(_thread_machdep_switch)

	/* new window */
	save	%sp, -SA(MINFRAME), %sp

	/* flush all windows (except current one) into memory frames */
	flushw

	/* switch the stack pointer and return address */
	st 	%fp, [%i1 + 0]
	st	%i7, [%i1 + 4]
	ld	[%i0 + 0], %fp
	ld	[%i0 + 4], %i7

	/* return to saved window at new %fp */
	ret
	restore