/*      $NetBSD: wdb00t.ahdi.S,v 1.4 2025/11/19 09:43:28 nia Exp $      */

/*
 * Copyright (c) 1995 Waldi Ravens
 * All rights reserved.
 *
 * 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "xxboot.h"

        .globl  _start, main, fill

        .text

_start: bras    main
        bra     rds0

main:   bclr    #2,(_drvbits+3):w
        clrl    pun_ptr:w
        movml   %d3/%d5,%sp@-
        movw    #-1,%sp@-
        movw    #Kbshift,%sp@-
        trap    #BIOS
        addql   #4,%sp
        btst    #3,%d0                  | Alternate?
        bnes    exit
        movq    #3,%d0
        lea     %pc@(p0_dsc),%a0
        movb    %d5,%d1                 | NVRAM bootpref
        bnes    0f

        | The Hades bios does not provide a bootprev. In case
        | of doubt, we fetch it ourselves.
        movb    #BOOTPREF,rtcrnr:w
        movb    rtcdat:w,%d1
        bnes    0f
        movq    #-8,%d1                 | bootpref = any

0:      movb    %a0@,%d2                        | bootflags
        btst    #0,%d2
        beqs    1f
        andb    %d1,%d2
        bnes    boot
1:      lea     %a0@(12),%a0
        dbra    %d0,0b

exit:   movml   %sp@+,%d3/%d5
tostst: clrw    _bootdev:w
        movl    _sysbase:w,%a0
        movl    %a0@(24),%d0
        swap    %d0
        cmpl    #0x19870422,%d0         | old TOS?
        bccs    0f                      | no
        movw    #0xe0,%d7
0:      rts

boot:   movl    %a0@(4),%d6
        movq    #1,%d5
        lea     %pc@(end),%a4
        bsrs    rds0
        tstw    %d0
        bnes    exit
        movl    %a4,%a0
        movw    #0xff,%d0
        movq    #0,%d1
0:      addw    %a0@+,%d1
        dbra    %d0,0b
        cmpw    #0x1234,%d1
        bnes    exit
        lea     %pc@(rds0),%a3
        lea     %pc@(tostst),%a5
        movml   %sp@+,%d3/%d5
        jmp     %a4@                    | start bootsector code
/*
 * in:  d4 (target) d5 (count), d6 (offset), a4 (buffer)
 * out: d0 (<= 0)
 * mod: d0, d1, d2, a0, a1, a5, a6
 */
rds0:   lea     %pc@(dpar),%a6
        tstb    %a6@
        bnes    0f
        movb    %d4,%d0
        andb    #1,%d0
        aslb    #4,%d0
        orb     #0xa0,%d0
        movb    %d0,idesdh:l
        movl    %a4,%a0
        movq    #0,%d1
        movb    #0,idedor:l
        movb    #0xec,idecr:l           | IDENTIFY DRIVE
        bsrs    wait
        bnes    err
        movb    %a4@(7),%a6@            | tracks/cylinder
        movb    %a4@(13),%a6@(1)                | sectors/track
0:      movl    %d6,%d1
        movq    #0,%d0
        movb    %a6@(1),%d0
        movq    #0,%d2
        movb    %a6@,%d2
        mulu    %d0,%d2
        divu    %d2,%d1
        movb    %d1,idecl:l
        lsrl    #8,%d1
        movb    %d1,idech:l
        lsrl    #8,%d1
        divu    %d0,%d1
        movb    %d4,%d0
        andb    #1,%d0
        aslb    #4,%d0
        orb     %d0,%d1
        orb     #0xa0,%d1
        movb    %d1,idesdh:l
        swap    %d1
        addqw   #1,%d1
        movb    %d1,idesn:l
        movl    %a4,%a0
        movb    %d5,idesc:l
        movw    %d5,%d1
        subqw   #1,%d1
        movb    #0,idedor:l
        movb    #0x20,idecr:l
wait:   movl    #0x7d0,%d0
        addl    _hz_200:w,%d0
2:      btst    #5,gpip:w
        beqs    3f
        cmpl    _hz_200:w,%d0
        bhis    2b
err:    movq    #-1,%d0
        rts
3:      movb    idesr:l,%d0
        btst    #0,%d0
        bnes    err
        btst    #3,%d0
        beqs    err
        movq    #63,%d0
        lea     idedr:l,%a1
4:      movw    %a1@,%a0@+
        movw    %a1@,%a0@+
        movw    %a1@,%a0@+
        movw    %a1@,%a0@+
        dbra    %d0,4b
        dbra    %d1,wait
        movq    #0,%d0
        rts

fill:   .space  52

dpar:   .byte   0                       | tracks/cylinder
        .byte   0                       | sectors/track
        .ascii  "NetBSD"
hd_siz: .long   0
p0_dsc: .long   0, 0, 0
p1_dsc: .long   0, 0, 0
p2_dsc: .long   0, 0, 0
p3_dsc: .long   0, 0, 0
bsl_st: .long   0
bsl_sz: .long   0
        .word   0
end: