C/C++ Interactive Guide/c-cplusplus-interactive-guide.iso/c_ref/csource4/208_01/e8.c

C/C++ Source or Header | 1987-10-13 | 4.6 KB | 192 lines

/*
HEADER:        CUG208;
TITLE:        'e' for CP/M68K
VERSION:    1.48b

DESCRIPTION:    "a screen editor";

KEYWORDS:    editor;
SYSTEM:        CP/M68K, V1.2;
FILENAME:    e/e8.c
WARNINGS:    "the default value is for systems with 128K bytes
         of memory or more";
SEE-ALSO:    cpm68k.c, e68k.doc, CUG VOL 133;
AUTHORS:    G.N.Gilbert('e'), J.W.Haefner(for DeSmet C on MSDOS and UNIX)
CODER:        Yoshimasa Tsuji
COMPILERS:    DRI C(Alcyon C) for CP/M68K;
*/
/*
    FUNCTIONS: loc,getline,inject,delete,puttext,
            readtext,balloc,error,addhistory
    PURPOSE: get and put text lines into and out of storage
*/

#include "e.h"


loc(line,move)    /*returns line+move, adjusted to be within text*/
register int line;
register int move;
{
register int y;

    if ( (y=line+move) < 1) y=1;
    if (lastl == UNKNOWN && y > lastread) readtext(y);
    if (y > lastl) return(lastl);
    return(y);
}
/*
 * signed short as an index to tp[] will create a boundary error.
 *        11/June/1987 Y. Tsuji
 */
char *
getline(line)    /*returns address of text of line 'line' and updates
                page usage*/
register int line;
{
    register int slot;

    line = loc(line,0);
    if ( (slot=pageloc[tp[(unsigned)line].page]) <= 0)
        slot=swappin(tp[(unsigned)line].page);
    if (usage[slot] >= INUSE) usage[slot]= ++clock;
    return(slotaddr[slot] + tp[(unsigned)line].moffset);
}

inject(line,txt)    /* inserts 'txt' after 'line' */
register int line;
char *txt;
{

    int p;

    addhistory(line,HISTINSERT);
    if ((char *)&(tp[(unsigned)lastread+2]) >= slotaddr[tppages]) {
        /*need another slot to store tp's in */
        if (tppages+2 >= slotsinmem) {
            error("Too many lines of text");
            return(FAIL);
        }
        if (usage[tppages] == NOTAVAIL) /*ie page is being alloc'ed into*/
            allocp= PAGESIZE+1; /*force balloc into new page*/
#ifdef DEBUG
        else if(usage[tppages] == FREE)
            putstr("\007\007");
#endif
        swapout(tppages);
        usage[tppages++]= NOTAVAIL;
    }

    /* CPM68K specific function blkmove
     *        blkmov(to, from, bytes)
     */

    if (++line < ++lastread)
        blkmove(&tp[(unsigned)line+1], &tp[(unsigned)line], (lastread-line)*sizeof(struct addr) );
    tp[(unsigned)line].moffset=p=balloc(1+strlen(txt));
    tp[(unsigned)line].page=newpage;
    strcpy(npaddr+ p,txt);
    if (lastl != UNKNOWN)lastl++;
    return(line);
}

delete(ffrom)    /*deletes a line by shifting pointers*/
register int ffrom;
{

    addhistory(ffrom,HISTDELETE);
    blkmove(&tp[(unsigned)ffrom], &tp[(unsigned)ffrom +1], (lastread-ffrom)*sizeof(struct addr) );
    if (lastl != UNKNOWN) lastl--;
    lastread--;
    if (lastl < 1)lastl=1;
    if (lastread < 1)lastread=1;
}

puttext()    /*replaces cline's text if it has been altered*/
{
register int p, cp;
    if (altered) {
        addhistory(cline,HISTREPLACE);
        altered=NO;
        if (!trail) {
            for(cp=strlen(text)-1;cp>=0 && isspace(text[cp]);
                cp--) text[cp]= '\0';
        }
        tp[(unsigned)cline].moffset=p=balloc(1+strlen(text));
        tp[(unsigned)cline].page=newpage;
        strcpy(npaddr+ p,text);
    }
}

readtext(line)    /*reads file being edited into virtual memory until 'line'
          is read, or eof.  If eof, sets lastl to number of last line
          read.  File is assumed to be already open*/
int line;
{
    char txt[LLIM];
    register char *t;
    register int i, c, l;

    storehist=NO;
    while (lastread < line) {
        for (i=0, t= &txt[0]; i < LLIM && ((c= fgetc(textfp)) >= ' ' ||
            c != '\n' && c != EOF); i++) {
                if (c) *t++ =c;
            else i--;
        }
        *t='\0';
        if ((l=inject(lastread,txt)) == FAIL) {lastl=lastread;break;}
        else if ((lastread=l)%100 == 0) ptlineno(l);
        if (goteof= c == EOF) { fclose(textfp);lastl=lastread;
            break; }
        checkkey();
    }
    storehist=YES;
}

balloc(n)    /*allocate and return the offset in newpage of a vector size n*/
int n;
{
    register short slot;
    if (allocp  + n >= PAGESIZE) {
        /*no room in current newpage; get another*/
        if (pageloc[newpage] > 0)usage[pageloc[newpage]]=INUSE;
        pageloc[++newpage]=slot=freememslot();
        usage[slot]= NOTAVAIL;
        allocp=0;
        npaddr=slotaddr[slot];
    }
    allocp+=n;

    return(allocp-n);
}

error(message)
char *message;
{
    if (errmess) return;
    gotoxy(32,0);
    putstr(errmess=message);
    resetcursor();
    inbufp=0;
}

addhistory(l,type)
register int l;
short type;
{
    register struct histstep *step;

    if(!storehist) return;

    step= &history[histptr];
    if (++histptr == HISTLEN) histptr=0;
    if (histcnt < HISTLEN) histcnt++;

    step->histp.page=tp[(unsigned)l].page;
    step->histp.moffset=tp[(unsigned)l].moffset;
    step->histline=l;
    step->histtype=type;
    step->histcomm=ncommand;
}