Category : Miscellaneous Language Source Code
Archive   : OVL312.ZIP
Filename : SPLIT.C

/* SPLIT.C

programmed in the small memory model of Turbo C version 2.0

splits root file appended overlay files into separate files with
the extension of .001, .002, etc.

*/

#include "stdio.h"
#include "dos.h"
#include "string.h"
#include "io.h"

FILE *fpin,*fpout;

char fname[128];
char f_noext_name[125]; /* file name in fname without extension */
unsigned char header[27];
char inbuff[4096]; /* file inbuffer for setvbuf */
char outbuff[4096]; /* file outbuffer for setvbuf */
char transbuff[512]; /* file bytes transfer buffer */

int filecount=0;

void operate();
int split(char *workname);

void main(int argc, char *argv[])
{
char *period_pos; /* position of period in fname */

if(argc<2){ /* file name was not provided on command line */
cprintf("\n\rInput overlay file to split\r\n");
gets(fname);
}
else{ /* command link provided file name */
strcpy(fname,argv[1]);
}
strcpy(f_noext_name,fname);
if((period_pos=strchr(f_noext_name,'.'))==NULL){ /* need to add default .exe file extension */
strcat(fname,".exe"); /* add the .exe extension */
}
else{
period_pos[0]=0; /* kill the extension */
}
operate();
}

void operate()
{
char workname[128];
char file_ext[5]; /* file extension; .$$$, .001, .002, etc. */

if((fpin=fopen(fname,"rb"))==NULL){ /* error opening file */
printf("\n\007Error opening file %s",fname);
exit(1);
}
setvbuf(fpin,inbuff,_IOFBF,4096); /* speed up i/o */
while(!feof(fpin)){ /* split out .exe files until end of file or invalid .EXE information */
strcpy(workname,f_noext_name);
/* get appropriate extension for work file */
sprintf(file_ext,!filecount?".$$$":".%03d",filecount);
strcat(workname,file_ext); /* add extension to the work file name */
if(split(workname)){
break; /* all done splitting out files */
}
filecount++; /* increment count of files split */
}
fclose(fpin);
/* no errors, kill old file, rename temporary .$$$ file to old name */
strcpy(workname,f_noext_name);
strcat(workname,".$$$");
unlink(fname);
rename(workname,fname);
printf("\nSplit complete: %d overlay file%s",filecount-1,filecount!=2?"s":"");
}

int split(char *workname)
{
int signature,ovl_number;
unsigned long loop;
unsigned long filelen; /* length of .exe file (overlay or root) */

fread(header,27,1,fpin); /* read in first 27 .exe header bytes */
fseek(fpin,-27L,SEEK_CUR); /* position back to start of .exe file */

signature=(header[0]=='M' && header[1]=='Z'); /* check for valid MZ .exe signature */
ovl_number=header[26]; /* get overlay number */
if(!signature || ovl_number!=filecount){ /* header bytes have invalid values */
return(1); /* not a proper .EXE file to split */
}

if((fpout=fopen(workname,"wb"))==NULL){ /* error opening file */
printf("\n\007Error opening file %s",workname);
exit(1);
}
setvbuf(fpout,outbuff,_IOFBF,4096); /* speed up i/o */

filelen=header[5];
filelen*=256L;
filelen+=header[4];
filelen*=512L; /* get length of .exe file to nearest 512 byte page */
for(loop=0L;loop<=filelen-512L;loop+=512L){ /* transfer in 512 byte chunks */
fread(transbuff,1,512,fpin);
fwrite(transbuff,1,512,fpout);
}
/* transfer leftover bytes */
fread(transbuff,1,filelen%512,fpin);
fwrite(transbuff,1,filelen%512,fpout);

fclose(fpout);
return(0); /* successful file split */
}