compilers/linux86-0.16.17/bootblocks/lsys.c

   1
   2 #include "msdos.v"
   3 #include "msdos16.v"
   4
   5 #define DOS_SYSID       0x03
   6 #define DOS_SECT        0x0B
   7 #define DOS_CLUST       0x0D
   8 #define DOS_RESV        0x0E
   9 #define DOS_NFAT        0x10
  10 #define DOS_NROOT       0x11
  11 #define DOS_MAXSECT     0x13
  12 #define DOS_MEDIA       0x15
  13 #define DOS_FATLEN      0x16
  14 #define DOS_SPT         0x18
  15 #define DOS_HEADS       0x1A
  16 #define DOS_HIDDEN      0x1C
  17 #define DOS4_MAXSECT    0x20
  18 #define DOS4_PHY_DRIVE  0x24
  19 #define DOS4_SERIAL     0x27
  20 #define DOS4_LABEL      0x2B
  21 #define DOS4_FATTYPE    0x36
  22
  23 unsigned char buffer[1024];
  24
  25 int drive = 0;
  26
  27 main(argc, argv)
  28 int argc;
  29 char ** argv;
  30 {
  31    int tries, rv, i;
  32
  33    if( argc > 1 )
  34    {
  35       static char * s = "Usage: lsys [a:]\n";
  36       if( argc == 2 && argv[1][1] == ':' && argv[1][2] <= ' ' )
  37       {
  38          if( argv[1][0] == 'a' || argv[1][0] == 'A' )
  39             drive = 0;
  40          else if( argv[1][0] == 'b' || argv[1][0] == 'B' )
  41             drive = 1;
  42          else
  43             fatal(s);
  44       }
  45       else
  46          fatal(s);
  47    }
  48
  49    for(tries=0; tries<6; tries++)
  50       if( (rv = dos_sect_read(drive, 0, 0, 1, buffer)) == 0 )
  51          break;
  52    if( rv == 0 )
  53       for(tries=0; tries<6; tries++)
  54          if( (rv = dos_sect_read(drive, 0, 0, 2, buffer+512)) == 0 )
  55             break;
  56    if( rv ) fatal("Cannot read bootsector");
  57
  58    if( buffer[DOS_MEDIA] != buffer[512] ||
  59        buffer[DOS_MEDIA] < 0xF0 ||
  60        buffer[DOS_NFAT] > 2 ||
  61        buffer[DOS_SECT+1] != 2 )
  62       fatal("Floppy has invalid format");
  63
  64    if( memcmp(buffer+DOS4_FATTYPE, "FAT16", 5) )
  65    {
  66       for(i=0; i<msdos_dosfs_stat - msdos_start; i++)
  67          buffer[i] = msdos_data[i];
  68       for(i=msdos_codestart - msdos_start; i<512; i++)
  69          buffer[i] = msdos_data[i];
  70    }
  71    else
  72    {
  73       for(i=0; i<msdos16_dosfs_stat - msdos_start; i++)
  74          buffer[i] = msdos16_data[i];
  75       for(i=msdos_codestart - msdos_start; i<512; i++)
  76          buffer[i] = msdos16_data[i];
  77    }
  78
  79    for(tries=0; tries<6; tries++)
  80       if( (rv = dos_sect_write(drive, 0, 0, 1, buffer)) == 0 )
  81          break;
  82    if( rv ) fatal("Cannot write bootsector");
  83
  84    write(0, "Wrote bootsector\r\n", 18);
  85    return 0;
  86 }
  87
  88 fatal(str)
  89 {
  90    write(0, str, strlen(str));
  91    write(0, "\r\n", 2);
  92    exit(1);
  93 }
  94
  95 dos_sect_write(drv, track, head, sector, loadaddr)
  96 {
  97 #asm
  98   push  bp
  99   mov   bp,sp
 100
 101   push  ds
 102   pop   es
 103
 104   mov   dh,[bp+2+_dos_sect_write.head]
 105   mov   dl,[bp+2+_dos_sect_write.drv]
 106   mov   cl,[bp+2+_dos_sect_write.sector]
 107   mov   ch,[bp+2+_dos_sect_write.track]
 108
 109   mov   bx,[bp+2+_dos_sect_write.loadaddr]
 110
 111   mov   ax,#$0301
 112   int   $13
 113   jc    write_err
 114   mov   ax,#0
 115 write_err:
 116
 117   pop   bp
 118 #endasm
 119 }
 120
 121 dos_sect_read(drv, track, head, sector, loadaddr)
 122 {
 123 #asm
 124   push  bp
 125   mov   bp,sp
 126
 127   push  ds
 128   pop   es
 129
 130   mov   dh,[bp+2+_dos_sect_read.head]
 131   mov   dl,[bp+2+_dos_sect_read.drv]
 132   mov   cl,[bp+2+_dos_sect_read.sector]
 133   mov   ch,[bp+2+_dos_sect_read.track]
 134
 135   mov   bx,[bp+2+_dos_sect_read.loadaddr]
 136
 137   mov   ax,#$0201
 138   int   $13
 139   jc    read_err
 140   mov   ax,#0
 141 read_err:
 142
 143   pop   bp
 144 #endasm
 145 }
 146