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Add additional int15 handlers for disk drives.

This commit is contained in:
Kevin O'Connor 2008-03-01 22:16:32 -05:00
parent b8aacb065b
commit e43df9ea52
2 changed files with 527 additions and 149 deletions
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611
src/disk.c
View File

@ -20,6 +20,143 @@ disk_ret(struct bregs *regs, u8 code)
set_cf(regs, code);
}
#define DISK_STUB(regs) do { \
struct bregs *__regs = (regs); \
debug_stub(__regs); \
disk_ret(__regs, DISK_RET_SUCCESS); \
} while (0)
static u8
checksum_seg(u16 seg, u16 offset, u32 len)
{
u32 i;
u8 sum = 0;
for (i=0; i<len; i++)
sum += GET_FARVAR(seg, *(u8*)(offset+i));
return sum;
}
static void
basic_access(struct bregs *regs, u8 device, u16 command)
{
u16 count = regs->al;
u16 cylinder = regs->ch | ((((u16) regs->cl) << 2) & 0x300);
u16 sector = regs->cl & 0x3f;
u16 head = regs->dh;
if ((count > 128) || (count == 0) || (sector == 0)) {
BX_INFO("int13_harddisk: function %02x, parameter out of range!\n"
, regs->ah);
disk_ret(regs, DISK_RET_EPARAM);
return;
}
u16 nlc = GET_EBDA(ata.devices[device].lchs.cylinders);
u16 nlh = GET_EBDA(ata.devices[device].lchs.heads);
u16 nlspt = GET_EBDA(ata.devices[device].lchs.spt);
u16 nph = GET_EBDA(ata.devices[device].pchs.heads);
u16 npspt = GET_EBDA(ata.devices[device].pchs.spt);
// sanity check on cyl heads, sec
if ( (cylinder >= nlc) || (head >= nlh) || (sector > nlspt )) {
BX_INFO("int13_harddisk: function %02x, parameters out of"
" range %04x/%04x/%04x!\n"
, regs->ah, cylinder, head, sector);
disk_ret(regs, DISK_RET_EPARAM);
return;
}
u32 lba = 0;
// if needed, translate lchs to lba, and execute command
if ( (nph != nlh) || (npspt != nlspt)) {
lba = (((((u32)cylinder * (u32)nlh) + (u32)head) * (u32)nlspt)
+ (u32)sector - 1);
sector = 0; // this forces the command to be lba
}
u16 segment = regs->es;
u16 offset = regs->bx;
u8 status;
switch (command) {
case ATA_CMD_READ_SECTORS:
status = ata_cmd_data_in(device, ATA_CMD_READ_SECTORS
, count, cylinder, head, sector
, lba, segment, offset);
break;
case ATA_CMD_WRITE_SECTORS:
status = ata_cmd_data_out(device, ATA_CMD_WRITE_SECTORS
, count, cylinder, head, sector
, lba, segment, offset);
break;
default:
disk_ret(regs, DISK_RET_SUCCESS);
return;
}
// Set nb of sector transferred
regs->al = GET_EBDA(ata.trsfsectors);
if (status != 0) {
BX_INFO("int13_harddisk: function %02x, error %02x !\n",regs->ah,status);
disk_ret(regs, DISK_RET_EBADTRACK);
}
disk_ret(regs, DISK_RET_SUCCESS);
}
static void
extended_access(struct bregs *regs, u8 device, u16 command)
{
u16 count = GET_INT13EXT(regs, count);
u16 segment = GET_INT13EXT(regs, segment);
u16 offset = GET_INT13EXT(regs, offset);
// Can't use 64 bits lba
u32 lba = GET_INT13EXT(regs, lba2);
if (lba != 0L) {
BX_PANIC("int13_harddisk: function %02x. Can't use 64bits lba\n"
, regs->ah);
disk_ret(regs, DISK_RET_EPARAM);
return;
}
// Get 32 bits lba and check
lba = GET_INT13EXT(regs, lba1);
if (lba >= GET_EBDA(ata.devices[device].sectors)) {
BX_INFO("int13_harddisk: function %02x. LBA out of range\n", regs->ah);
disk_ret(regs, DISK_RET_EPARAM);
return;
}
u8 status;
switch (command) {
case ATA_CMD_READ_SECTORS:
status = ata_cmd_data_in(device, ATA_CMD_READ_SECTORS
, count, 0, 0, 0
, lba, segment, offset);
break;
case ATA_CMD_WRITE_SECTORS:
status = ata_cmd_data_out(device, ATA_CMD_WRITE_SECTORS
, count, 0, 0, 0
, lba, segment, offset);
break;
default:
// If verify or seek
disk_ret(regs, DISK_RET_SUCCESS);
return;
}
SET_INT13EXT(regs, count, GET_EBDA(ata.trsfsectors));
if (status != 0) {
BX_INFO("int13_harddisk: function %02x, error %02x !\n"
, regs->ah, status);
disk_ret(regs, DISK_RET_EBADTRACK);
return;
}
disk_ret(regs, DISK_RET_SUCCESS);
}
// disk controller reset
static void
disk_1300(struct bregs *regs, u8 device)
@ -35,134 +172,28 @@ disk_1301(struct bregs *regs, u8 device)
disk_ret(regs, DISK_RET_SUCCESS);
}
static int
check_params(struct bregs *regs, u8 device)
{
u16 count = regs->al;
u16 cylinder = regs->ch | ((((u16) regs->cl) << 2) & 0x300);
u16 sector = regs->cl & 0x3f;
u16 head = regs->dh;
if ((count > 128) || (count == 0) || (sector == 0)) {
BX_INFO("int13_harddisk: function %02x, parameter out of range!\n"
, regs->ah);
disk_ret(regs, DISK_RET_EPARAM);
return -1;
}
u16 nlc = GET_EBDA(ata.devices[device].lchs.cylinders);
u16 nlh = GET_EBDA(ata.devices[device].lchs.heads);
u16 nlspt = GET_EBDA(ata.devices[device].lchs.spt);
// sanity check on cyl heads, sec
if ( (cylinder >= nlc) || (head >= nlh) || (sector > nlspt )) {
BX_INFO("int13_harddisk: function %02x, parameters out of"
" range %04x/%04x/%04x!\n"
, regs->ah, cylinder, head, sector);
disk_ret(regs, DISK_RET_EPARAM);
return -1;
}
return 0;
}
// read disk sectors
static void
disk_1302(struct bregs *regs, u8 device)
{
int ret = check_params(regs, device);
if (ret)
return;
u16 count = regs->al;
u16 cylinder = regs->ch | ((((u16) regs->cl) << 2) & 0x300);
u16 sector = regs->cl & 0x3f;
u16 head = regs->dh;
u16 nph = GET_EBDA(ata.devices[device].pchs.heads);
u16 npspt = GET_EBDA(ata.devices[device].pchs.spt);
u16 nlh = GET_EBDA(ata.devices[device].lchs.heads);
u16 nlspt = GET_EBDA(ata.devices[device].lchs.spt);
u32 lba = 0;
// if needed, translate lchs to lba, and execute command
if ( (nph != nlh) || (npspt != nlspt)) {
lba = (((((u32)cylinder * (u32)nlh) + (u32)head) * (u32)nlspt)
+ (u32)sector - 1);
sector = 0; // this forces the command to be lba
}
u16 segment = regs->es;
u16 offset = regs->bx;
u8 status = ata_cmd_data_in(device, ATA_CMD_READ_SECTORS
, count, cylinder, head, sector
, lba, segment, offset);
// Set nb of sector transferred
regs->al = GET_EBDA(ata.trsfsectors);
if (status != 0) {
BX_INFO("int13_harddisk: function %02x, error %02x !\n",regs->ah,status);
disk_ret(regs, DISK_RET_EBADTRACK);
}
disk_ret(regs, DISK_RET_SUCCESS);
basic_access(regs, device, ATA_CMD_READ_SECTORS);
}
// write disk sectors
static void
disk_1303(struct bregs *regs, u8 device)
{
int ret = check_params(regs, device);
if (ret)
return;
u16 count = regs->al;
u16 cylinder = regs->ch | ((((u16) regs->cl) << 2) & 0x300);
u16 sector = regs->cl & 0x3f;
u16 head = regs->dh;
u16 nph = GET_EBDA(ata.devices[device].pchs.heads);
u16 npspt = GET_EBDA(ata.devices[device].pchs.spt);
u16 nlh = GET_EBDA(ata.devices[device].lchs.heads);
u16 nlspt = GET_EBDA(ata.devices[device].lchs.spt);
u32 lba = 0;
// if needed, translate lchs to lba, and execute command
if ( (nph != nlh) || (npspt != nlspt)) {
lba = (((((u32)cylinder * (u32)nlh) + (u32)head) * (u32)nlspt)
+ (u32)sector - 1);
sector = 0; // this forces the command to be lba
}
u16 segment = regs->es;
u16 offset = regs->bx;
u8 status = ata_cmd_data_out(device, ATA_CMD_READ_SECTORS
, count, cylinder, head, sector
, lba, segment, offset);
// Set nb of sector transferred
regs->al = GET_EBDA(ata.trsfsectors);
if (status != 0) {
BX_INFO("int13_harddisk: function %02x, error %02x !\n",regs->ah,status);
disk_ret(regs, DISK_RET_EBADTRACK);
}
disk_ret(regs, DISK_RET_SUCCESS);
basic_access(regs, device, ATA_CMD_WRITE_SECTORS);
}
// verify disk sectors
static void
disk_1304(struct bregs *regs, u8 device)
{
int ret = check_params(regs, device);
if (ret)
return;
basic_access(regs, device, 0);
// FIXME verify
disk_ret(regs, DISK_RET_SUCCESS);
}
#define DISK_STUB(regs) do { \
struct bregs *__regs = (regs); \
debug_stub(__regs); \
disk_ret(__regs, DISK_RET_SUCCESS); \
} while (0)
// format disk track
static void
disk_1305(struct bregs *regs, u8 device)
@ -191,6 +222,27 @@ disk_1308(struct bregs *regs, u8 device)
disk_ret(regs, DISK_RET_SUCCESS);
}
// initialize drive parameters
static void
disk_1309(struct bregs *regs, u8 device)
{
DISK_STUB(regs);
}
// seek to specified cylinder
static void
disk_130c(struct bregs *regs, u8 device)
{
DISK_STUB(regs);
}
// alternate disk reset
static void
disk_130d(struct bregs *regs, u8 device)
{
DISK_STUB(regs);
}
// check drive ready
static void
disk_1310(struct bregs *regs, u8 device)
@ -205,6 +257,20 @@ disk_1310(struct bregs *regs, u8 device)
disk_ret(regs, DISK_RET_ENOTREADY);
}
// recalibrate
static void
disk_1311(struct bregs *regs, u8 device)
{
DISK_STUB(regs);
}
// controller internal diagnostic
static void
disk_1314(struct bregs *regs, u8 device)
{
DISK_STUB(regs);
}
// read disk drive size
static void
disk_1315(struct bregs *regs, u8 device)
@ -223,41 +289,253 @@ disk_1315(struct bregs *regs, u8 device)
regs->ah = 3; // hard disk accessible
}
// IBM/MS installation check
static void
disk_1341(struct bregs *regs, u8 device)
{
regs->bx = 0xaa55; // install check
regs->cx = 0x0007; // ext disk access and edd, removable supported
disk_ret(regs, DISK_RET_SUCCESS);
regs->ah = 0x30; // EDD 3.0
}
// IBM/MS extended read
static void
disk_1342(struct bregs *regs, u8 device)
{
extended_access(regs, device, ATA_CMD_READ_SECTORS);
}
// IBM/MS extended write
static void
disk_1343(struct bregs *regs, u8 device)
{
extended_access(regs, device, ATA_CMD_WRITE_SECTORS);
}
// IBM/MS verify
static void
disk_1344(struct bregs *regs, u8 device)
{
extended_access(regs, device, 0);
}
// IBM/MS lock/unlock drive
static void
disk_1345(struct bregs *regs, u8 device)
{
// Always success for HD
disk_ret(regs, DISK_RET_SUCCESS);
}
// IBM/MS eject media
static void
disk_1346(struct bregs *regs, u8 device)
{
// Volume Not Removable
disk_ret(regs, DISK_RET_ENOTREMOVABLE);
}
// IBM/MS extended seek
static void
disk_1347(struct bregs *regs, u8 device)
{
extended_access(regs, device, 0);
}
// IBM/MS get drive parameters
static void
disk_1348(struct bregs *regs, u8 device)
{
u16 size = GET_INT13DPT(regs, size);
// Buffer is too small
if (size < 0x1a) {
disk_ret(regs, DISK_RET_EPARAM);
return;
}
// EDD 1.x
u16 npc = GET_EBDA(ata.devices[device].pchs.cylinders);
u16 nph = GET_EBDA(ata.devices[device].pchs.heads);
u16 npspt = GET_EBDA(ata.devices[device].pchs.spt);
u32 lba = GET_EBDA(ata.devices[device].sectors);
u16 blksize = GET_EBDA(ata.devices[device].blksize);
SET_INT13DPT(regs, size, 0x1a);
if ((lba/npspt)/nph > 0x3fff) {
SET_INT13DPT(regs, infos, 0x00); // geometry is invalid
SET_INT13DPT(regs, cylinders, 0x3fff);
} else {
SET_INT13DPT(regs, infos, 0x02); // geometry is valid
SET_INT13DPT(regs, cylinders, (u32)npc);
}
SET_INT13DPT(regs, heads, (u32)nph);
SET_INT13DPT(regs, spt, (u32)npspt);
SET_INT13DPT(regs, sector_count1, lba); // FIXME should be Bit64
SET_INT13DPT(regs, sector_count2, 0L);
SET_INT13DPT(regs, blksize, blksize);
if (size < 0x1e) {
disk_ret(regs, DISK_RET_SUCCESS);
return;
}
// EDD 2.x
SET_INT13DPT(regs, size, 0x1e);
SET_INT13DPT(regs, dpte_segment, EBDA_SEG);
SET_INT13DPT(regs, dpte_offset
, offsetof(struct extended_bios_data_area_s, ata.dpte));
// Fill in dpte
u8 channel = device / 2;
u16 iobase1 = GET_EBDA(ata.channels[channel].iobase1);
u16 iobase2 = GET_EBDA(ata.channels[channel].iobase2);
u8 irq = GET_EBDA(ata.channels[channel].irq);
u8 mode = GET_EBDA(ata.devices[device].mode);
u8 translation = GET_EBDA(ata.devices[device].translation);
u16 options = (translation==ATA_TRANSLATION_NONE?0:1)<<3; // chs translation
options |= (1<<4); // lba translation
options |= (mode==ATA_MODE_PIO32?1:0)<<7;
options |= (translation==ATA_TRANSLATION_LBA?1:0)<<9;
options |= (translation==ATA_TRANSLATION_RECHS?3:0)<<9;
SET_EBDA(ata.dpte.iobase1, iobase1);
SET_EBDA(ata.dpte.iobase2, iobase2 + ATA_CB_DC);
SET_EBDA(ata.dpte.prefix, (0xe | (device % 2))<<4 );
SET_EBDA(ata.dpte.unused, 0xcb );
SET_EBDA(ata.dpte.irq, irq );
SET_EBDA(ata.dpte.blkcount, 1 );
SET_EBDA(ata.dpte.dma, 0 );
SET_EBDA(ata.dpte.pio, 0 );
SET_EBDA(ata.dpte.options, options);
SET_EBDA(ata.dpte.reserved, 0);
if (size >= 0x42)
SET_EBDA(ata.dpte.revision, 0x11);
else
SET_EBDA(ata.dpte.revision, 0x10);
u8 sum = checksum_seg(EBDA_SEG
, offsetof(struct extended_bios_data_area_s, ata.dpte)
, 15);
SET_EBDA(ata.dpte.checksum, ~sum);
if (size < 0x42) {
disk_ret(regs, DISK_RET_SUCCESS);
return;
}
// EDD 3.x
channel = device / 2;
u8 iface = GET_EBDA(ata.channels[channel].iface);
iobase1 = GET_EBDA(ata.channels[channel].iobase1);
SET_INT13DPT(regs, size, 0x42);
SET_INT13DPT(regs, key, 0xbedd);
SET_INT13DPT(regs, dpi_length, 0x24);
SET_INT13DPT(regs, reserved1, 0);
SET_INT13DPT(regs, reserved2, 0);
if (iface==ATA_IFACE_ISA) {
SET_INT13DPT(regs, host_bus[0], 'I');
SET_INT13DPT(regs, host_bus[1], 'S');
SET_INT13DPT(regs, host_bus[2], 'A');
SET_INT13DPT(regs, host_bus[3], 0);
} else {
// FIXME PCI
}
SET_INT13DPT(regs, iface_type[0], 'A');
SET_INT13DPT(regs, iface_type[1], 'T');
SET_INT13DPT(regs, iface_type[2], 'A');
SET_INT13DPT(regs, iface_type[3], 0);
if (iface==ATA_IFACE_ISA) {
SET_INT13DPT(regs, iface_path[0], iobase1);
SET_INT13DPT(regs, iface_path[2], 0);
SET_INT13DPT(regs, iface_path[4], 0L);
} else {
// FIXME PCI
}
SET_INT13DPT(regs, device_path[0], device%2);
SET_INT13DPT(regs, device_path[1], 0);
SET_INT13DPT(regs, device_path[2], 0);
SET_INT13DPT(regs, device_path[4], 0L);
sum = checksum_seg(regs->ds, 30, 34);
SET_INT13DPT(regs, checksum, ~sum);
}
// IBM/MS extended media change
static void
disk_1349(struct bregs *regs, u8 device)
{
// Always success for HD
disk_ret(regs, DISK_RET_SUCCESS);
}
static void
disk_134e01(struct bregs *regs, u8 device)
{
disk_ret(regs, DISK_RET_SUCCESS);
}
static void
disk_134e03(struct bregs *regs, u8 device)
{
disk_ret(regs, DISK_RET_SUCCESS);
}
static void
disk_134e04(struct bregs *regs, u8 device)
{
disk_ret(regs, DISK_RET_SUCCESS);
}
static void
disk_134e06(struct bregs *regs, u8 device)
{
disk_ret(regs, DISK_RET_SUCCESS);
}
static void
disk_134eXX(struct bregs *regs, u8 device)
{
debug_stub(regs);
disk_ret(regs, DISK_RET_EPARAM);
}
// IBM/MS set hardware configuration
static void
disk_134e(struct bregs *regs, u8 device)
{
switch (regs->al) {
case 0x01: disk_134e01(regs, device); break;
case 0x03: disk_134e03(regs, device); break;
case 0x04: disk_134e04(regs, device); break;
case 0x06: disk_134e06(regs, device); break;
default: disk_134eXX(regs, device); break;
}
}
static void
disk_13XX(struct bregs *regs, u8 device)
{
BX_INFO("int13_harddisk: function %xh unsupported, returns fail\n", regs->ah);
debug_stub(regs);
disk_ret(regs, DISK_RET_EPARAM);
}
static void
disk_13(struct bregs *regs, u8 drive)
disk_13(struct bregs *regs, u8 device)
{
if (! CONFIG_ATA) {
disk_13XX(regs, drive);
return;
}
//debug_stub(regs);
// clear completion flag
SET_BDA(disk_interrupt_flag, 0);
// basic check : device has to be defined
if (drive < 0x80 || drive >= 0x80 + CONFIG_MAX_ATA_DEVICES) {
disk_13XX(regs, drive);
return;
}
// Get the ata channel
u8 device = GET_EBDA(ata.hdidmap[drive-0x80]);
// basic check : device has to be valid
if (device >= CONFIG_MAX_ATA_DEVICES) {
disk_13XX(regs, drive);
return;
}
switch (regs->ah) {
case 0x00: disk_1300(regs, device); break;
case 0x01: disk_1301(regs, device); break;
@ -266,13 +544,55 @@ disk_13(struct bregs *regs, u8 drive)
case 0x04: disk_1304(regs, device); break;
case 0x05: disk_1305(regs, device); break;
case 0x08: disk_1308(regs, device); break;
case 0x09: disk_1309(regs, device); break;
case 0x0c: disk_130c(regs, device); break;
case 0x0d: disk_130d(regs, device); break;
case 0x10: disk_1310(regs, device); break;
case 0x11: disk_1311(regs, device); break;
case 0x14: disk_1314(regs, device); break;
case 0x15: disk_1315(regs, device); break;
// XXX - several others defined
case 0x41: disk_1341(regs, device); break;
case 0x42: disk_1342(regs, device); break;
case 0x43: disk_1343(regs, device); break;
case 0x44: disk_1344(regs, device); break;
case 0x45: disk_1345(regs, device); break;
case 0x46: disk_1346(regs, device); break;
case 0x47: disk_1347(regs, device); break;
case 0x48: disk_1348(regs, device); break;
case 0x49: disk_1349(regs, device); break;
case 0x4e: disk_134e(regs, device); break;
default: disk_13XX(regs, device); break;
}
}
static void
cdrom_13(struct bregs *regs, u8 device)
{
// XXX
disk_13XX(regs, device);
}
static u8
get_device(struct bregs *regs, u8 drive)
{
// basic check : device has to be defined
if (drive >= CONFIG_MAX_ATA_DEVICES) {
disk_ret(regs, DISK_RET_EPARAM);
return CONFIG_MAX_ATA_DEVICES;
}
// Get the ata channel
u8 device = GET_EBDA(ata.hdidmap[drive]);
// basic check : device has to be valid
if (device >= CONFIG_MAX_ATA_DEVICES) {
disk_ret(regs, DISK_RET_EPARAM);
return CONFIG_MAX_ATA_DEVICES;
}
return device;
}
static void
handle_legacy_disk(struct bregs *regs, u8 drive)
{
@ -280,14 +600,25 @@ handle_legacy_disk(struct bregs *regs, u8 drive)
floppy_13(regs, drive);
return;
}
#if BX_USE_ATADRV
if (drive >= 0xE0) {
int13_cdrom(regs); // xxx
if (! CONFIG_ATA) {
// XXX - old code had other disk access method.
disk_ret(regs, DISK_RET_EPARAM);
return;
}
#endif
disk_13(regs, drive);
if (drive >= 0xe0) {
u8 device = get_device(regs, drive - 0xe0);
if (device >= CONFIG_MAX_ATA_DEVICES)
return;
cdrom_13(regs, device);
return;
}
u8 device = get_device(regs, drive - 0x80);
if (device >= CONFIG_MAX_ATA_DEVICES)
return;
disk_13(regs, device);
}
void VISIBLE

65
src/disk.h
View File

@ -9,15 +9,62 @@
#include "ioport.h" // outb
#include "biosvar.h" // struct bregs
#define DISK_RET_SUCCESS 0x00
#define DISK_RET_EPARAM 0x01
#define DISK_RET_ECHANGED 0x06
#define DISK_RET_EBOUNDARY 0x09
#define DISK_RET_EBADTRACK 0x0c
#define DISK_RET_ECONTROLLER 0x20
#define DISK_RET_ETIMEOUT 0x80
#define DISK_RET_EMEDIA 0xC0
#define DISK_RET_ENOTREADY 0xAA
#define DISK_RET_SUCCESS 0x00
#define DISK_RET_EPARAM 0x01
#define DISK_RET_ECHANGED 0x06
#define DISK_RET_EBOUNDARY 0x09
#define DISK_RET_EBADTRACK 0x0c
#define DISK_RET_ECONTROLLER 0x20
#define DISK_RET_ETIMEOUT 0x80
#define DISK_RET_ENOTREMOVABLE 0xb2
#define DISK_RET_EMEDIA 0xC0
#define DISK_RET_ENOTREADY 0xAA
// Bios disk structures.
struct int13ext_s {
u8 size;
u8 reserved;
u16 count;
u16 offset;
u16 segment;
u32 lba1;
u32 lba2;
};
#define GET_INT13EXT(regs,var) \
GET_FARVAR((regs)->ds, ((struct int13ext_s*)((regs)->si+0))->var)
#define SET_INT13EXT(regs,var,val) \
SET_FARVAR((regs)->ds, ((struct int13ext_s*)((regs)->si+0))->var, (val))
// Disk Physical Table definition
struct int13dpt_s {
u16 size;
u16 infos;
u32 cylinders;
u32 heads;
u32 spt;
u32 sector_count1;
u32 sector_count2;
u16 blksize;
u16 dpte_offset;
u16 dpte_segment;
u16 key;
u8 dpi_length;
u8 reserved1;
u16 reserved2;
u8 host_bus[4];
u8 iface_type[8];
u8 iface_path[8];
u8 device_path[8];
u8 reserved3;
u8 checksum;
};
#define GET_INT13DPT(regs,var) \
GET_FARVAR((regs)->ds, ((struct int13dpt_s*)((regs)->si+0))->var)
#define SET_INT13DPT(regs,var,val) \
SET_FARVAR((regs)->ds, ((struct int13dpt_s*)((regs)->si+0))->var, (val))
// floppy.c
void floppy_13(struct bregs *regs, u8 drive);