www.pudn.com > bootmenu.zip > S_MSDOS.C

/* This file contains system-specific functions for MS-DOS. 
 * The program pfdisk.c calls these routines. 
 */ 
#include  
#include  
#include  
#include  
#include  
 
#define extern 
#include "sysdep.h" 
#undef extern 
 
int usage(prog)	/* print a usage message */ 
char	*prog;	/* program name */ 
{ 
  fprintf(stderr,"Usage: %s \n", prog); 
  fprintf(stderr,"\twhere  is a digit [0-9]\n"); 
} 
 
void getGeometry(name, c, h, s) 
char	*name;		/* device name */ 
unsigned *c,*h,*s;	/* cyls, heads, sectors */ 
{ 
  int dev;	/* hard disk number */ 
  union 	REGS	regs; 
  struct	SREGS	sregs; 
   
  if (name[0] < '0' || 
      name[0] > '9' || 
      name[1] != 0  ) 
    { 
      fprintf(stderr,"%s: device name must be a digit\n", name); 
      return; 
    } 
  dev = (name[0] - '0'); 
   
  regs.h.ah = 8;		/* get param.	*/ 
  regs.h.dl = dev | 0x80; 
   
  int86x(0x13,®s,®s,&sregs); 
   
  /* Are that many drives responding? */ 
  if (regs.h.dl <= dev ) { 
    fprintf(stderr,"%s: drive not found\n", name); 
    return; 
  } 
  if (regs.x.cflag) { 
    fprintf(stderr,"%s: can't get disk parameters\n", name); 
    return; 
  } 
  *c = ((((int) regs.h.cl << 2) & 0x300) | regs.h.ch) + 1; 
  *h = regs.h.dh + 1; 
  *s = regs.h.cl & 0x3F; 
} 
 
int getFile(name, buf, len)	/* read file into buffer */ 
char	*name, *buf; 
int	len; 
{	/* (open, read, close) */ 
  int devfd, retval; 
   
  devfd = open(name, O_RDONLY|O_BINARY, 0); 
  if (devfd < 0) { 
    fprintf(stderr,"%s: can't open for reading\n", name); 
    return(devfd); 
  } 
  retval = read(devfd, buf, len); 
  if (retval < 0) 
    fprintf(stderr,"%s: read failed\n", name); 
  close(devfd); 
  return(retval); 
} 
 
int putFile(name, buf, len)	/* write buffer to file */ 
char	*name, *buf; 
int	len; 
{	/* (open, write, close) */ 
  int devfd, retval; 
   
  devfd = open(name, 
	       O_WRONLY|O_CREAT|O_BINARY, 
	       S_IREAD|S_IWRITE ); /* stupid DOS... */ 
  if (devfd < 0) { 
    fprintf(stderr,"%s: can't open for writing\n", name); 
    return(devfd); 
  } 
  retval = write(devfd, buf, len); 
  if (retval < 0) 
    fprintf(stderr,"%s: write failed\n", name); 
  close(devfd); 
  return(retval); 
} 
 
int getBBlk(name, buf)	/* read boot block into buffer */ 
char	*name, *buf; 
{	/* BIOS absolute disk read */ 
  int dev; 
  union 	REGS	regs; 
  struct	SREGS	sregs; 
   
  if (name[0] < '0' || 
      name[0] > '9' || 
      name[1] != 0  ) 
    { 
      fprintf(stderr,"%s: device name must be a digit\n",name); 
      return(-1); 
    } 
  dev = (name[0] - '0'); 
   
  segread(&sregs);	/* get ds */ 
  sregs.es = sregs.ds;	/* buffer address */ 
  regs.x.bx = (int) buf; 
   
  regs.h.ah = 2;		/* read		*/ 
  regs.h.al = 1;		/* sector count	*/ 
  regs.h.ch = 0;		/* track	*/ 
  regs.h.cl = 1;		/* start sector	*/ 
  regs.h.dh = 0;		/* head		*/ 
  regs.h.dl = dev|0x80;	/* drive	*/ 
   
  int86x(0x13,®s,®s,&sregs); 
  if (regs.x.cflag) { 
    fprintf(stderr,"%s: read failed\n", name); 
    return(-1); 
  } 
  return(SECSIZE); 
} 
 
int putBBlk(name, buf)	/* write buffer to boot block */ 
char	*name, *buf; 
{	/* BIOS absolute disk write */ 
  int dev; 
  union 	REGS	regs; 
  struct	SREGS	sregs; 
   
  if (name[0] < '0' || 
      name[0] > '9' || 
      name[1] != 0  ) 
    { 
      fprintf(stderr,"%s: device name must be a digit\n", name); 
      return(-1); 
    } 
  dev = (name[0] - '0'); 
   
  segread(&sregs);	/* get ds */ 
  sregs.es = sregs.ds;	/* buffer address */ 
  regs.x.bx = (int) buf; 
   
  regs.h.ah = 3;		/* write	*/ 
  regs.h.al = 1;		/* sector count	*/ 
  regs.h.ch = 0;		/* track	*/ 
  regs.h.cl = 1;		/* start sector	*/ 
  regs.h.dh = 0;		/* head		*/ 
  regs.h.dl = dev|0x80;	/* drive	*/ 
   
  int86x(0x13,®s,®s,&sregs); 
  if (regs.x.cflag) { 
    fprintf(stderr,"%s: write failed\n",name); 
    return(-1); 
  } 
  return(SECSIZE); 
}