/*      $NetBSD: _lwp.c,v 1.10 2025/04/27 16:15:40 riastradh Exp $      */

/*-
* Copyright (c) 2001 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Nathan J. Williams.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: _lwp.c,v 1.10 2025/04/27 16:15:40 riastradh Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"

#include <sys/param.h>
#include <sys/types.h>

#include <lwp.h>
#include <stdlib.h>
#include <ucontext.h>

void
_lwp_makecontext(ucontext_t *u, void (*start)(void *),
   void *arg, void *private, caddr_t stack_base, size_t stack_size)
{
       __greg_t *gr;

       getcontext(u);
       gr = u->uc_mcontext.__gregs;

       u->uc_link = NULL;

       u->uc_stack.ss_sp = stack_base;
       u->uc_stack.ss_size = stack_size;

       gr[_REG_PC] = (unsigned long)start;
       gr[_REG_T12] = (unsigned long) start;
       gr[_REG_RA] = (unsigned long) _lwp_exit;
       gr[_REG_A0] = (unsigned long) arg;
       gr[_REG_SP] = ((unsigned long) (stack_base + stack_size)) &
           ~STACK_ALIGNBYTES;
       gr[_REG_S6] = 0;
       gr[_REG_UNIQUE] = (unsigned long)private;

       u->uc_flags |= _UC_TLSBASE;
}