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Intwrapped biosdisk

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This commit is contained in:
Vladimir 'phcoder' Serbinenko 2010-04-04 18:43:26 +02:00
parent 42c4f00016
commit 77356db852
5 changed files with 162 additions and 272 deletions
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160
disk/i386/pc/biosdisk.c
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@ -83,6 +83,166 @@ grub_biosdisk_rw_int13_extensions (int ah, int drive, void *dap)
return (regs.eax >> 8) & 0xff;
}
/*
* Call standard and old INT13 (int 13 %ah=AH) for DRIVE. Read/write
* NSEC sectors from COFF/HOFF/SOFF into SEGMENT. If an error occurs,
* return non-zero, otherwise zero.
*/
static int
grub_biosdisk_rw_standard (int ah, int drive, int coff, int hoff,
int soff, int nsec, int segment)
{
int ret, i;
/* Try 3 times. */
for (i = 0; i < 3; i++)
{
struct grub_bios_int_registers regs;
/* set up CHS information */
/* set %ch to low eight bits of cylinder */
regs.ecx = (coff << 8) & 0xff00;
/* set bits 6-7 of %cl to high two bits of cylinder */
regs.ecx |= (coff >> 2) & 0xc0;
/* set bits 0-5 of %cl to sector */
regs.ecx |= soff & 0x3f;
/* set %dh to head and %dl to drive */
regs.edx = (drive & 0xff) | ((hoff << 8) & 0xff00);
/* set %ah to AH */
regs.eax = (ah << 8) & 0xff00;
/* set %al to NSEC */
regs.eax |= nsec & 0xff;
regs.ebx = 0;
regs.es = segment;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
/* check if successful */
if (!(regs.flags & GRUB_CPU_INT_FLAGS_CARRY))
return 0;
/* save return value */
ret = regs.eax >> 8;
/* if fail, reset the disk system */
regs.eax = 0;
regs.edx = (drive & 0xff);
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
}
return ret;
}
/*
* Check if LBA is supported for DRIVE. If it is supported, then return
* the major version of extensions, otherwise zero.
*/
static int
grub_biosdisk_check_int13_extensions (int drive)
{
struct grub_bios_int_registers regs;
regs.edx = drive & 0xff;
regs.eax = 0x4100;
regs.ebx = 0x55aa;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
if (regs.flags & GRUB_CPU_INT_FLAGS_CARRY)
return 0;
if ((regs.ebx & 0xffff) != 0xaa55)
return 0;
/* check if AH=0x42 is supported */
if (!(regs.ecx & 1))
return 0;
return (regs.eax >> 8) & 0xff;
}
/*
* Return the geometry of DRIVE in CYLINDERS, HEADS and SECTORS. If an
* error occurs, then return non-zero, otherwise zero.
*/
static int
grub_biosdisk_get_diskinfo_standard (int drive,
unsigned long *cylinders,
unsigned long *heads,
unsigned long *sectors)
{
struct grub_bios_int_registers regs;
regs.eax = 0x0800;
regs.edx = drive & 0xff;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
/* Check if unsuccessful. Ignore return value if carry isn't set to
workaround some buggy BIOSes. */
if ((regs.flags & GRUB_CPU_INT_FLAGS_CARRY) && ((regs.eax & 0xff00) != 0))
return (regs.eax & 0xff00) >> 8;
/* bogus BIOSes may not return an error number */
/* 0 sectors means no disk */
if (!(regs.ecx & 0x3f))
/* XXX 0x60 is one of the unused error numbers */
return 0x60;
/* the number of heads is counted from zero */
*heads = ((regs.edx >> 8) & 0xff) + 1;
*cylinders = (((regs.ecx >> 8) & 0xff) | ((regs.ecx << 2) & 0x0300)) + 1;
*sectors = regs.ecx & 0x3f;
return 0;
}
static int
grub_biosdisk_get_diskinfo_real (int drive, void *drp, grub_uint16_t ax)
{
struct grub_bios_int_registers regs;
regs.eax = ax;
/* compute the address of drive parameters */
regs.esi = ((grub_addr_t) drp) & 0xf;
regs.ds = ((grub_addr_t) drp) >> 4;
regs.edx = drive & 0xff;
regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
grub_bios_interrupt (0x13, &regs);
/* Check if unsuccessful. Ignore return value if carry isn't set to
workaround some buggy BIOSes. */
if ((regs.flags & GRUB_CPU_INT_FLAGS_CARRY) && ((regs.eax & 0xff00) != 0))
return (regs.eax & 0xff00) >> 8;
return 0;
}
/*
* Return the cdrom information of DRIVE in CDRP. If an error occurs,
* then return non-zero, otherwise zero.
*/
static int
grub_biosdisk_get_cdinfo_int13_extensions (int drive, void *cdrp)
{
return grub_biosdisk_get_diskinfo_real (drive, cdrp, 0x4b01);
}
/*
* Return the geometry of DRIVE in a drive parameters, DRP. If an error
* occurs, then return non-zero, otherwise zero.
*/
static int
grub_biosdisk_get_diskinfo_int13_extensions (int drive, void *drp)
{
return grub_biosdisk_get_diskinfo_real (drive, drp, 0x4800);
}
static int
grub_biosdisk_get_drive (const char *name)
{