What is the function of dos.h?

Answer 1

You can find a copy of that file in here:

http://ftp.ibiblio.org/pub/micro/PC-stuff/freedos/files/devel/c/dos.h

in case the server is down check the extracted file:

#ifndef __DOS_H

#define __DOS_H

#include <_defs.h>

#include <stddef.h>

#ifdef __WATCOMC__

#pragma pack( __push, 1 )

#endif

struct _R16BIT {

unsigned short ax, bx, cx, dx, si, di, es, cs, ss, ds, flags;

unsigned char cflag;

};

struct _R8BIT {

unsigned char al, ah, bl, bh, cl, ch, dl, dh;

};

union _INTR {

struct _R16BIT x;

struct _R8BIT h;

};

#define INTR _INTR

struct country {

int co_date; /* date format */

char co_curr[ 5 ]; /* currency symbol */

char co_thsep[ 2 ]; /* thousands separator */

char co_desep[ 2 ]; /* decimal separator */

char co_dtsep[ 2 ]; /* date separator */

char co_tmsep[ 2 ]; /* time separator */

char co_currstyle; /* currency style */

char co_digits; /* significant digits in currency */

char co_time; /* time format */

long co_case; /* case map */

char co_dasep[ 2 ]; /* data separator */

char co_fill[ 10 ]; /* filler */

};

#define COUNTRY country

struct DOSERROR {

int de_exterror; /* extended error */

char de_class; /* error class */

char de_action; /* action */

char de_locus; /* error locus */

};

struct date {

unsigned int da_year; /* current year */

unsigned char da_day; /* day of the month */

unsigned char da_mon; /* month (1 = Jan) */

};

struct dosdate_t {

unsigned char day; /* 1--31 */

unsigned char month; /* 1--12 */

unsigned int year; /* 1980--2099 */

unsigned char dayofweek; /* 0--6; 0 = Sunday */

};

struct devhdr {

long dh_next;

short dh_attr;

unsigned short dh_strat;

unsigned short dh_inter;

char dh_name[ 8 ];

};

struct dfree {

unsigned df_avail; /* Available clusters */

unsigned df_total; /* Total clusters */

unsigned df_bsec; /* Bytes per sector */

unsigned df_sclus; /* Sectors per cluster */

};

struct diskfree_t {

unsigned total_clusters;

unsigned avail_clusters;

unsigned sectors_per_cluster;

unsigned bytes_per_sector;

};

typedef struct {

char drive;

char pattern [ 13 ];

char reserved [ 7 ];

char attrib;

short time;

short date;

long size;

char nameZ [ 13 ];

} dosSearchInfo;

struct fatinfo {

char fi_sclus; /* sectors per cluster */

char fi_fatid; /* the FAT id byte */

int fi_nclus; /* number of clusters */

int fi_bysec; /* bytes per sector */

};

struct ffblk {

#ifdef __CLIB_LFN__

unsigned short cr_time; /* time of file creation */

unsigned short cr_date; /* date of file creation */

unsigned short ac_time; /* time of last file access */

unsigned short ac_date; /* date of last file access */

char ff_reserved[ 13 ]; /* reserved for use by DOS */

#else

char ff_reserved[ 21 ]; /* reserved for use by DOS */

#endif

char ff_attrib; /* attribute byte for file */

unsigned short ff_ftime; /* time of last write to file */

unsigned short ff_fdate; /* date of last write to file */

unsigned long ff_fsize; /* length of file in bytes */

#ifdef __CLIB_LFN__

char ff_name[ 256 ]; /* null-terminated filename */

unsigned short lfnhandle;/* DOS LFN support handle */

#else

char ff_name[ 13 ]; /* null-terminated filename */

#endif

};

struct find_t {

#ifdef __CLIB_LFN__

unsigned short cr_time; /* time of file creation */

unsigned short cr_date; /* date of file creation */

unsigned short ac_time; /* time of last file access */

unsigned short ac_date; /* date of last file access */

char reserved[ 13 ]; /* reserved for use by DOS */

#else

char reserved[ 21 ]; /* reserved for use by DOS */

#endif

char attrib; /* attribute byte for file */

unsigned short wr_time; /* time of last write to file */

unsigned short wr_date; /* date of last write to file */

unsigned long size; /* length of file in bytes */

#ifdef __CLIB_LFN__

char name[ 256 ]; /* null-terminated filename */

unsigned short lfnhandle;/* DOS LFN support handle */

#else

char name[ 13 ]; /* null-terminated filename */

#endif

};

#define _find_t find_t

struct fcb {

char fcb_drive;

char fcb_name[ 8 ],

fcb_ext[ 3 ];

short fcb_curblk,

fcb_recsize;

long fcb_filsize;

short fcb_date;

char fcb_resv[ 10 ],

fcb_currec;

long fcb_random;

};

struct xfcb {

char xfcb_flag;

char xfcb_resv[ 5 ];

char xfcb_attr;

struct fcb xfcb_fcb;

};

struct dostime_t {

unsigned char hour; /* Hours */

unsigned char minute; /* Minutes */

unsigned char second; /* Seconds */

unsigned char hsecond; /* Hundredths of seconds */

};

struct time {

unsigned char ti_min; /* minutes */

unsigned char ti_hour; /* hours */

unsigned char ti_hund; /* hundredths of seconds */

unsigned char ti_sec; /* seconds */

};

#ifdef __WATCOMC__

#pragma pack( __pop )

#endif

extern int __getversion( void );

extern char ** environ;

#define _version (*__getversion)()

extern unsigned char _osmajor;

extern unsigned char _osminor;

extern int absread( int drive, int sects, long lsect, void *buffer );

extern int abswrite( int drive, int sects, long lsect, void *buffer );

extern int allocmem( unsigned size, unsigned *seg );

extern int bdos( int ah, unsigned dx, unsigned al );

extern int bdosptr( int ah, void *argument, unsigned al );

extern int _callint( union INTR *regs );

extern struct COUNTRY *

country( int xcode, struct COUNTRY *ct );

extern void ctrlbrk( int ( *handler )( void ) );

extern void delay( unsigned mill );

extern void _disable( void );

extern unsigned _dos_allocmem( unsigned size, unsigned *seg );

extern unsigned _dos_close( int handle );

extern unsigned _dos_creat( const char *path, int attr, unsigned *handle );

extern unsigned _dos_creatnew( const char *path, int attr, unsigned *handle );

extern int __cdecl dosexterror( struct DOSERROR *errblk );

extern unsigned _dos_findfirst( char *filename, int attrib, void *strptr );

extern unsigned _dos_findnext( void *strptr );

extern unsigned _dos_findclose( void *strptr );

extern unsigned _dos_freemem( unsigned seg );

extern void __cdecl _dos_getdate( struct dosdate_t *ptr );

extern unsigned __cdecl

_dos_getdiskfree( unsigned char dr, struct diskfree_t *d );

extern unsigned _dos_getdrive( unsigned *disk );

extern unsigned _dos_getfileattr( const char *filename, unsigned *attrs );

extern unsigned __cdecl

_dos_getftime( int handle,

unsigned *date,

unsigned *time );

extern void __cdecl _dos_gettime( struct dostime_t *timeptr );

extern void ( interrupt far *

_dos_getvect( unsigned intno ) )( );

extern void _dos_keep( unsigned char retcode, unsigned size );

extern unsigned _dos_open( const char *path, unsigned flags, unsigned *handle );

extern unsigned _dos_read( int handle,

void far *buf,

unsigned len,

unsigned *nread );

extern unsigned _dos_setblock( unsigned newsize,

unsigned seg,

unsigned *max );

extern void _dos_setdate( struct dosdate_t *ptr );

extern void _dos_setdrive( unsigned disk, unsigned *total );

extern unsigned _dos_setfileattr( const char *filename, unsigned attrs );

extern unsigned _dos_setftime( int handle, unsigned date, unsigned time );

extern unsigned _dos_settime( struct dostime_t *timeptr );

extern void _dos_setvect( unsigned intno,

void ( interrupt far *vect )() );

extern time_t dostounix( struct date *date, struct time *time );

extern unsigned _dos_write( int handle,

void far *buf,

unsigned len,

unsigned *bytes );

extern void _enable( void );

extern int freemem( unsigned seg );

extern int getcbrk( void );

extern void __cdecl getdate( struct date *datep );

extern void __cdecl getdfree( unsigned char drive, struct dfree *dtable );

extern char * getdta( void );

extern void getfat( unsigned char drive, struct fatinfo *dtable );

extern void getfatd( struct fatinfo *dtable );

extern unsigned getpsp( void );

extern void __cdecl gettime( struct time *timeptr );

extern void ( interrupt far *

getvect( int intno ) )( );

extern int getverify( void );

extern int inp( unsigned id );

extern unsigned inpw( unsigned id );

extern unsigned inport( unsigned id );

extern unsigned char inportb( unsigned id );

extern void keep( unsigned char retcode, unsigned size );

extern void nosound( void );

extern int outp( unsigned id, int value );

extern unsigned outpw( unsigned id, unsigned value );

extern void outport( unsigned id, unsigned value );

extern void outportb( unsigned id, unsigned char value );

extern char * parsfnm( const char *cmdline, struct fcb *ptr, int al );

extern int peek( unsigned seg, unsigned offs );

extern char peekb( unsigned seg, unsigned offs );

extern void poke( unsigned seg, unsigned offs, int value );

extern void pokeb( unsigned seg, unsigned offs, char value );

extern int randbrd( struct fcb *buf, int rnum );

extern int randbwr( struct fcb *buf, int rnum );

extern int setblock( unsigned newsize, unsigned seg );

extern int setcbrk( int value );

extern void setdate( struct date *datep );

extern void setdta( char far *dta );

extern void setpsp( unsigned psp );

extern void settime( struct time *timeptr );

extern void setvect( int intno, void ( interrupt far *vect )() );

extern void setverify( int flag );

extern void sleep( unsigned x );

extern void sound( unsigned frequency );

extern void unixtodos( time_t longtime,

struct date *date,

struct time *time );

extern int unlink( const char *filename );

#define disable _disable

#define enable _enable

#define _A_NORMAL 0x00

#define _A_RDONLY 0x01

#define _A_HIDDEN 0x02

#define _A_SYSTEM 0x04

#define _A_VOLID 0x08

#define _A_SUBDIR 0x10

#define _A_ARCH 0x20

#define FA_NORMAL _A_NORMAL

#define FA_RDONLY _A_RDONLY

#define FA_HIDDEN _A_HIDDEN

#define FA_SYSTEM _A_SYSTEM

#define FA_LABEL _A_VOLID

#define FA_DIREC _A_SUBDIR

#define FA_ARCH _A_ARCH

#define NFDS 20

#define SEEK_SET 0

#define SEEK_CUR 1

#define SEEK_END 2

#define MK_FP( seg, ofs ) ( ( void * )\

( ( ( unsigned long )( seg ) << 16 ) |\

( unsigned )( ofs ) ) )

#define FP_SEG(fp) ( ( unsigned )( ( unsigned long )( fp ) >> 16 ) )

#define FP_OFF(fp) ( ( unsigned )( fp ) )

#define __peek( a,b ) ( *( ( int far * ) MK_FP ( ( a ), ( b ) ) ) )

#define __peekb( a,b ) ( *( ( char far * ) MK_FP ( ( a ), ( b ) ) ) )

#define __poke( a,b,c ) ( *( ( int far * ) MK_FP ( (a),(b)) ) = ( int )(c))

#define __pokeb( a,b,c ) ( *( ( char far * ) MK_FP ( (a),(b)) ) = ( char )(c))

#define peek( a,b ) ( *( ( int far * ) MK_FP ( ( a ), ( b ) ) ) )

#define peekb( a,b ) ( *( ( char far * ) MK_FP ( ( a ), ( b ) ) ) )

#define poke( a,b,c ) ( *( ( int far * ) MK_FP ( (a),(b)) ) = ( int )(c))

#define pokeb( a,b,c ) ( *( ( char far * ) MK_FP ( (a),(b)) ) = ( char )(c))

#ifndef __NO_INLINE_FUNCTIONS

#pragma aux _enable = "sti";

#pragma aux _disable = "cli";

#pragma aux inp = "in al, dx" parm [dx] value [al] modify [ax dx];

#pragma aux inpw = "in ax, dx" parm [dx] value [ax] modify [ax dx];

#pragma aux inport = "in ax, dx" parm [dx] value [ax] modify [ax dx];

#pragma aux inportb = "in al, dx" parm [dx] value [al] modify [ax dx];

#pragma aux outp = "out dx, al" parm [dx] [al] value [al] modify [ax dx];

#pragma aux outpw = "out dx, ax" parm [dx] [ax] value [ax] modify [ax dx];

#pragma aux outport = "out dx, ax" parm [dx] [ax] modify [ax dx];

#pragma aux outportb = "out dx, al" parm [dx] [al] modify [ax dx];

#endif

#endif

Answer 2

dos.h is not a C standard header file. Consult the documentation for your C implementation.