src/arch/i386/drivers/bus/bios_disks.c

   1 #include "realmode.h"
   2
   3 #define CF ( 1 << 0 )
   4
   5 /**************************************************************************
   6 DISK_INIT - Initialize the disk system
   7 **************************************************************************/
   8 void disk_init ( void ) {
   9         REAL_EXEC ( rm_disk_init,
  10                     "sti\n\t"
  11                     "xorw %%ax,%%ax\n\t"
  12                     "movb $0x80,%%dl\n\t"
  13                     "int $0x13\n\t"
  14                     "cli\n\t",
  15                     0,
  16                     OUT_CONSTRAINTS (),
  17                     IN_CONSTRAINTS (),
  18                     CLOBBER ( "eax", "ebx", "ecx", "edx",
  19                               "ebp", "esi", "edi" ) );
  20 }
  21
  22 /**************************************************************************
  23 DISK_READ - Read a sector from disk
  24 **************************************************************************/
  25 unsigned int pcbios_disk_read ( int drive, int cylinder, int head, int sector,
  26                                 char *fixme_buf ) {
  27         uint16_t ax, flags, discard_c, discard_d;
  28         segoff_t buf = SEGOFF ( fixme_buf );
  29
  30         /* FIXME: buf should be passed in as a segoff_t rather than a
  31          * char *
  32          */
  33
  34         REAL_EXEC ( rm_pcbios_disk_read,
  35                     "sti\n\t"
  36                     "pushl %%ebx\n\t"      /* Convert %ebx to %es:bx */
  37                     "popw %%bx\n\t"
  38                     "popw %%es\n\t"
  39                     "movb $0x02, %%ah\n\t" /* INT 13,2 - Read disk sector */
  40                     "movb $0x01, %%al\n\t" /* Read one sector */
  41                     "int $0x13\n\t"
  42                     "pushfw\n\t"
  43                     "popw %%bx\n\t"
  44                     "cli\n\t",
  45                     4,
  46                     OUT_CONSTRAINTS ( "=a" ( ax ), "=b" ( flags ),
  47                                       "=c" ( discard_c ), "=d" ( discard_d ) ),
  48                     IN_CONSTRAINTS ( "c" ( ( ( cylinder & 0xff ) << 8 ) |
  49                                            ( ( cylinder >> 8 ) & 0x3 ) |
  50                                            sector ),
  51                                      "d" ( ( head << 8 ) | drive ),
  52                                      "b" ( buf ) ),
  53                     CLOBBER ( "ebp", "esi", "edi" ) );
  54
  55         return ( flags & CF ) ? ax : 0;
  56 }