Extracted from firmware/pcbios/bios.c
[people/lynusvaz/gpxe.git] / 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 }