#include "ded.h"
#include "char.h"
#include "file.h"

/************************************************************************
 *                                                                      *
 *                      copyright Richard Bornat 1981                   *
 *                                                                      *
 ************************************************************************/

/* file handler */

int f_tmp = -1;
int f_write;
char f_cache[512];
#define fpLIM &f_cache[511]
int f_cblock;           /* block offset of file cache */
int f_nblock;           /* where next write will go */

int tmp_block, tmp_offset; /* where the end of the temporary file is */

/* create the temporary file */
void maketemp(tname)
register char *tname;
 {  if (f_tmp == -1) /* not yet opened */
     {  if ((f_tmp = creat(tname, 0666)) == -1)
	  quit("cannot create temporary file %s", tname);
	close(f_tmp);
	if ((f_tmp = open(tname, 2)) == -1)
	  quit("cannot re-open temporary file %s", tname);
     }

    maxl = -1;
    tmp_block = tmp_offset = 0;
    tmp_changed = false;
    {   register int i;
	for (i=0; i<NLETTS; i++) b_range[i] = e_range[i] = -1;
    }
 }

/* the character which tags a line on the picture */
linetag(fline, linebuf)
register int fline;
register char *linebuf;
 {  register int i;

    *linebuf = ' ';             /* default no mark */

    for (i=0; i<NLETTS; i++)
      if (b_range[i]<=fline && e_range[i]>=fline)
       {  *linebuf = i+'a'+0200;        /* bright tags */
	  break;
       }

    /* one more space then a terminator */
    linebuf++; *linebuf++ = ' '; *linebuf = 0;
 }

getline(fline,linebuf)
register int fline;
register char *linebuf;
 {  if (topl<=fline && fline<=topl+LASTINROW)
     {  linetag(fline, linebuf); linebuf += MARGIN;
	copyrow(fline-topl,MARGIN,linebuf);
     }
    else
      getfline(fline,linebuf);
 }

/* gets a line from disk into store */
getfline(fline,linebuf)
int fline;
register char *linebuf;
 {  register char *fp;
    register unsigned lo = l_offset[fline];
    int block, offset;

    block = (lo>>7)&0777;
    offset = (lo<<2)&0777;

    linetag(fline, linebuf); linebuf += MARGIN;
    if (lo == (unsigned)-1 || fline>maxl)
      *linebuf = 0;
    else
     {  getblock(block, true);
	fp = f_cache+offset;

	while ((*linebuf++ = *fp++) != 0)
	    if (fp > fpLIM)
	     {  getblock(++block, true);
		 fp = f_cache;
	     }

	*linebuf = 0;
     }
    return;

}

/* writes the line in buf
 * onto the end of the file
 */

void addline(fline,linebuf)
int fline;
register char *linebuf;
 {  register char *fp;
    int block, offset;
    register char c;

    if (linebuf==0 || *linebuf==0)
       l_offset[fline] = -1;
    else
     {  block = tmp_block;
	offset = tmp_offset;
	getblock(block, offset!=0); f_write++;
	fp = f_cache + offset;

	do
	 { *fp++ = c = *linebuf++;

	    if (fp > fpLIM)
	     {  getblock(++block,false);
		f_write++;
		fp = f_cache;
	     }
	 } while (c != 0);

	if ((l_offset[fline] = (tmp_block<<7) | (tmp_offset>>2)) ==
							      (unsigned)-1 ||
		tmp_block>0777)
	  editerror("[addline] file too big");
	while ((tmp_offset = (fp-f_cache)) & 03) fp++;
	if (tmp_offset>=512)
	 { tmp_offset -= 512; block++; }
	tmp_block = block;
     }
}

emptyline(fline)
register int fline;
 { return(onscreen(fline) ? emptyrow(fline-topl) :
			    l_offset[fline] == (unsigned)-1); }


/* get a block from the tmp file into the cache buffer  */

seekit(block)
register int block;
 {  if (block!=f_nblock)
#ifdef V7
	lseek(f_tmp, ((long) block)*512, 0);
#else
	seek(f_tmp, block, 3);
#endif
 }

getblock(block,there)
register int block;
int there;
 {  register int oblock = f_cblock;

    if (oblock != block)
     {  /* write out old block if necessary */
	if (f_write)
	 {  seekit(oblock);
	    if (write(f_tmp, f_cache, 512) != 512)
	      editerror("tmp write failed[getblock] - out of space?");
	    else f_nblock = oblock+1;
	 }
	/* read in new block if necessary */
	if (there)
	 {  register int count;

	    seekit(block);
	    if ((count=read(f_tmp, f_cache, 512))<=0)
	      editerror("tmp read failed[getblock] - what goes on?");
	    else
	    if (count==512) f_nblock=block+1;
	    else f_nblock = -1;
	 }
	/* record new position */
	f_cblock=block; f_write = 0;
     }
 }