/* Copyright 2015 Yoshinori Sato <ysato@users.sourceforge.jp> */

/* clone is even more special than fork as it mucks with stacks
   and invokes a function in the right context after its all over.  */

#define _ERRNO_H
#include <bits/errno.h>
#include <sys/syscall.h>

/* int _clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg
		void *parent_tidptr, void *tls, void *child_tidptr)  */

#ifdef __H8300H__
	.h8300h
#endif
#ifdef __H8300S__
	.h8300s
#endif

.text
.globl	clone
clone:
	/* Sanity check arguments.  */
	mov.l	#-EINVAL,er3
	mov.l	er0,er0			/* no NULL function pointers */
	beq	__syscall_error
	mov.l	er1,er1			/* no NULL stack pointers */
	beq	__syscall_error

	/* Allocate space and copy the argument onto the new stack.  */
	mov.l	@(4:16,sp),er3
	mov.l	er3,@-er1

	/* setup argument */
	mov.l	er0,er3			/* er3 = child entry */
	sub.l	#20,sp
	mov.l	er2,@sp			/* flags */
	mov.l	er1,@(4,sp)		/* new sp */
	mov.l	sp,er1
	mov.l	@(20+8,sp),er0
	mov.l	er0,@er1		/* parent tid */
	adds	#4,er1
	mov.l	@(20+16,sp),er0
	mov.l	er0,@er1		/* child tid */
	adds	#4,er1
	mov.l	@(20+12,sp),er0
	mov.l	er0,@er1		/* tls */
	/* do the system call */
	mov.l	sp,er1
	mov.l	#__NR_clone,er0
	trapa	#0
	add.l	#20,sp
	mov.l	er0,er0
	bmi	__syscall_error
	beq	thread_start

	rts

__syscall_error:
	neg.l	er0
	mov.l	er0,@-sp
#if !defined(__PIC__)
	jsr	@__errno_location
#else
	mov.l	@(__errno_location@GOTOFF,er5),er1
	jsr	@er1
#endif
	mov.l	@sp,er1
	mov.l	er1,@er0
	sub.l	er0,er0
	dec.l	#1,er0

	rts

thread_start:
	mov.l	@sp+,er0		/* restore args */
	jsr     @er3
	mov.l	er0,er1
	mov.l	#__NR_exit,er0
	trapa	#0

	.end
