/*      $OpenBSD: start.S,v 1.7 2020/07/18 17:13:00 deraadt Exp $       */
/*      $NetBSD: start.S,v 1.4 1996/10/17 02:50:40 cgd Exp $    */

/*  
 * Mach Operating System
 * Copyright (c) 1992 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */

#include "include/asm.h"

/*
 * start --
 *      Entry point for boot/standalone programs.
 *
 * Arguments:
 *      a0                              long (first free physical page)
 *
 * This is where the prom comes to.  Leaves all exception and interrupts
 * to prom, runs off prom's stack too.  No return values.
 */
        .text
        .set    noreorder               /* don't reorder instructions */

#define ENTRY_FRAME     32

NESTED(start, 1, ENTRY_FRAME, ra, 0, 0)
        br      pv,Lstartgp
Lstartgp:
        LDGP(pv)

        lda     sp,start
#ifdef PRIMARY_BOOTBLOCK
        lda     sp,0x30000-ENTRY_FRAME(sp)
#else
        lda     sp,-ENTRY_FRAME(sp)     /* start stack below text */
#endif

        or      a0,zero,s0
        lda     a0,_edata
        lda     a1,_end
        subq    a1,a0,a1
        CALL(bzero)
        or      s0,zero,a0

        CALL(main)                      /* transfer to C */

XLEAF(_rtt, 0)
XLEAF(halt, 0)
        call_pal PAL_halt               /* halt if we ever return */
END(start)

/*
 * cpu_number
 *      Return the cpu number, using the whami instruction.
 */
LEAF(cpu_number, 0)
        call_pal PAL_VMS_mfpr_whami
        RET
END(cpu_number)