Added remaining bus functions.
[people/lynusvaz/gpxe.git] / src / drivers / disk / floppy.c
1 #if     (TRY_FLOPPY_FIRST > 0)
2
3 /*
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2, or (at
7  * your option) any later version.
8  */
9
10 #include "etherboot.h"
11
12 #define BOOTSECT ((char *)0x7C00)
13 #define BOOTSIG  ((unsigned short *)BOOTSECT)[0xFF]
14 #define PARTTAB  ((partentry *)(BOOTSECT+0x1BE))
15
16 typedef struct partentry {
17         unsigned char flags;
18         unsigned char start_head;
19         unsigned char start_sector;
20         unsigned char start_cylinder;
21         unsigned char type;
22         unsigned char end_head;
23         unsigned char end_sector;
24         unsigned char end_cylinder;
25         unsigned long offset;
26         unsigned long length;
27 } partentry;
28
29 static unsigned int disk_read_retry(int dev,int c,int h,int s)
30 {
31         int retry = 3,rc;
32
33         while (retry-- && (rc = pcbios_disk_read(dev,c,h,s,BOOTSECT)) != 0);
34         if (BOOTSIG != 0xAA55) {
35                 printf("not a boot sector");
36                 return(0xFFFF); }
37         return(rc);
38 }
39
40 int bootdisk(int dev,int part)
41 {
42         int rc;
43
44         disk_init();
45         if ((rc = disk_read_retry(dev,0,0,1)) != 0) {
46         readerr:
47                 if (rc != 0xFFFF)
48                         printf("read error (%#hhX)",rc/256);
49                 return(0); }
50         if (part) {
51                 partentry *ptr;
52
53                 if (part >= 5) {
54                         int i;
55                         for (i = 0, ptr = PARTTAB; ptr->type != 5; ptr++)
56                                 if (++i == 4) {
57                                         printf("partition not found");
58                                         return(0); }
59                         if ((rc = disk_read_retry(dev,
60                                                   ptr->start_cylinder,
61                                                   ptr->start_head,
62                                                   ptr->start_sector)) != 0)
63                                 goto readerr;
64                         part -= 4; }
65                 if (!(ptr = PARTTAB-1+part)->type) {
66                         printf("empty partition");
67                         return(0); }
68                 if ((rc = disk_read_retry(dev,
69                                           ptr->start_cylinder,
70                                           ptr->start_head,
71                                           ptr->start_sector)) != 0)
72                         goto readerr; }
73         cleanup();
74         gateA20_unset();
75         /* Set %edx to device number to emulate BIOS
76            Fortunately %edx is not used after this */
77         __asm__("movl %0,%%edx" : : "g" (dev));
78         xstart((unsigned long)BOOTSECT, 0, 0);
79         return(0);
80 }
81
82 #endif
83
84 /*
85  * Local variables:
86  *  c-basic-offset: 8
87  * End:
88  */