/*
 * Copyright 2009, François Revol, revol@free.fr.
 */

#define FUNCTION(x) .global x; .type x,@function; x

/*
 * stage1 boot code for AmigaDOS for use as boot block of HDD partitions.
 *
 * cf.
 * http://wandel.ca/homepage/execdis/virus_disassembly.txt
 * http://ciarang.com/wiki/page/Minimal_Amiga_Boot_Code
 *
 * x86:
 * The offset of the partition in 512 byte blocks must be written at
 * position PARTITION_OFFSET_OFFSET (32 bit little endian; makebootable does
 * that) or otherwise the code can't find the partition.
 * The partition must be a BFS formatted. The file "system/haiku_loader"
 * (the stage 2 boot loader) loaded into memory at 0x1000:0x0000 (linear address
 * 0x10000) and entered at 0x:1000:0x0200 with parameters eax - partition offset
 * in 512 byte blocks and dl - BIOS ID of the boot drive.
 * 
 * Compile via:
 * 
 * jam -q '<build>fixup_amiga_boot_checksum'
 * generated.m68k/cross-tools/bin/m68k-unknown-haiku-gcc -nostdlib -fpic -Wa,--pcrel -c -o stage1.o src/system/boot/platform/amiga_m68k/stage1.S
 * generated-m68k/cross-tools/bin/m68k-unknown-haiku-ld --oformat binary -o stage1.bin stage1.o
 * generated-m68k/objects/linux/x86/release/tools/fixup_amiga_boot_checksum/fixup_amiga_boot_checksum stage1.bin
 * generated.m68k/cross-tools/bin/m68k-unknown-haiku-ld -o stage1.prg stage1.o -T src/system/boot/platform/atari_m68k/prg.ld
 * 
 * Add to image:
 * dd if=/dev/zero bs=512 count=$((80*2*11)) of=df0.adf
 * dd if=stage1.bin bs=512 conv=notrunc of=df0.adf
 * 
 */


// 1 enabled verbose output
//#define DEBUG 1


#define BOOT_BLOCK_START_ADDRESS        0x7c00
#define STACK_ADDRESS                           BOOT_BLOCK_START_ADDRESS
#define READ_BUFFER_STACK                       STACK_ADDRESS - 0x2000
#define PARTITION_OFFSET_OFFSET         506
#define BFS_SUPERBLOCK_OFFSET           512


// BFS definitions

#define SUPER_BLOCK_MAGIC1                      '1SFB'          ; nasm reverses '...' consts
#define SUPER_BLOCK_MAGIC2                      0xdd121031
#define SUPER_BLOCK_MAGIC3                      0x15b6830e

#define INODE_MAGIC1                            0x3bbe0ad9

#define NUM_DIRECT_BLOCKS                       12

#define S_IFMT                                          00000170000o
#define S_IFDIR                                         00000040000o

// AmigaDOS calls
// exec.library
#define _Supervisor                             -0x1e
#define _FindResident                   -0x60
#define _Alert                                  -0x6c
#define _SuperState                             -0x96
#define _UserState                              -0x9c
#define _OldOpenLibrary         -0x198
#define _CloseLibrary           -0x19e
// dos.library
#define Old_mode                        1005
#define New_mode                        1006
#define _Open                                   -0x1e
#define _Close                                  -0x24
#define _Read                   -0x2a
#define _Write                  -0x30
#define _Input                                  -0x36
#define _Output                                 -0x3c
#define _IoErr                                  -0x84
#define _Delay                                  -0xc6
// intuition.library
#define _DisplayAlert                   -90


_floppy_entry:
        .ascii  "DOS"
//      .ascii  "BFS"
        .byte   0
_floppy_checksum:
        .long   0
_floppy_osversion: // ??
//_super_stack: // also used as a variable in the code
        //.long 0x370
        .long   0x09D5A859 // dos private ???

_floppy_boot:

        // we get an open IO request in A1

        // seems like a6 is already set to ExecBase when called from the ROM ?
        // copy it
        move.l  4.w,%a6
        lea             _execbase(%pc),%a2
        move.l  %a6,(%a2)

//      jsr             _SuperState(%a6)
//      move.l  %d0,_super_stack



//      bra _continue

/*
        move.l  %d0,%a6

        lea             window_name(%pc),%a0
        move.l  %a0,%d1
        move.l  #Old_mode,%d2
        jsr             _Open(%a6)
        tst.l   %d0
        beq.s   _floppy_err
_loop_1:
        bra             _loop_1


_loop_2:
        bra             _loop_2
*/      

        //lea _display_alert,%a5
        //jsr _Supervisor(%a6)

        jsr _display_alert


        bra     _floppy_err


//      lea     dosname_boot(%pc),%a1
////    jsr     -0x60(%a6)      // FindResident()
//      move.l  4.w,%a6
//      jsr     -96(%a6)


        tst.l   %d0
        beq.s   _floppy_err



_continue:
        move.l  4.w,%a6


        lea     dosname_boot(%pc),%a1
        jsr     _FindResident(%a6)
        lea     _dosbase(%pc),%a2
        tst.l   %d0
        beq.s   _floppy_err
        move.l  %d0,(%a2)

//      move.l  _super_stack,%d0
//      jsr             _UserState(%a6)

        move.l  _dosbase,%a0
        move.l  0x16(%a0),%a0

        moveq   #0,%d0

        rts

_floppy_err:
//      move.l  4.w,%a6
//      move.l  _super_stack,%d0
//      jsr             _UserState(%a6)

        moveq   #-1,%d0
        rts

_display_alert:
        move.l  4.w,%a6
        lea     intname_boot(%pc),%a1
        jsr     _OldOpenLibrary(%a6)
        tst.l   %d0
        beq.s   _floppy_err
        lea     _intbase(%pc),%a2
        move.l  %d0,(%a2)
        move.l  %d0,%a6

        lea             alert_data(%pc),%a0
        moveq   #0,%d0
        move.l  #30,%d1
        jsr             _DisplayAlert(%a6)
        rts

dosname_boot:
        .ascii  "dos.library"
        .byte   0

intname_boot:
        .ascii  "intuition.library"
        .byte   0

alert_data:
        .word   10
        .byte   12
        .ascii  "Welcome to Haiku\0"
alert_extra:
        .ascii  "\0\0"
        .byte   0

window_name:
        .ascii  "CON:0/0/640/255/plop\0"

_execbase:
        .long   0
_dosbase:
        .long   0
_intbase:
        .long   0

end_buff:
// equ *-_floppy_entry
        .dcb.b  (1024)-(end_buff-_floppy_entry),0