C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/vol_100/133_01/e8

Text File | 1985-03-09 | 4.4 KB | 213 lines

 /*
    e screen editor

    (C) G. Nigel Gilbert, MICROLOGY, 1981

    August-December 1981

    FILE: e8

    FUNCTIONS: loc,gettext,getline,inject,deltp,puttext,storetext,
            readtext,getc,opentext,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*/
int line, move;
{
    int y;

    if ( (y=line+move) < 1) y=1;
    if (lastl == UNKNOWN && y > lastread) readtext(y);
    if (y > lastl) return lastl;
    return y;
}

gettext(line)    /*makes 'line' the current line*/
int line;
{
    char *getline();

    strcpy(text,getline(line));
    cline=line;
}

char *getline(line)    /*returns address of text of line 'line' and updates
                page usage*/
int line;
{
    struct addr *tptr;
    int slot;

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

inject(line,txt)    /* inserts 'txt' after 'line' */
int line;
char *txt;
{
    int l;
    struct addr *tptr;

    addhistory(line,HISTINSERT);
    if ( &tp[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 alloc into new page*/
        if (usage[tppages] != FREE) swapout(tppages);
        usage[tppages++]=NOTAVAIL;
        }
    tptr=tp[++line];
    if (line < ++lastread)
        movmem(tptr,tptr+1,(lastread-line)*sizeof(*tptr));
    storetext(tptr,txt);
    if (lastl != UNKNOWN)lastl++;
    return line;
}

delete(from)    /*deletes a line by shifting pointers*/
int from;
{
    struct addr *tptr;

    addhistory(from,HISTDELETE);
    tptr=tp[from];
    movmem(tptr+1,tptr,(lastread-from)*sizeof(*tptr));
    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*/
{
    if (altered) {
        addhistory(cline,HISTREPLACE);
        altered=NO;
        storetext(tp[cline],text);
        }
}

storetext(tpptr,textptr)     /*stores text at textptr and updates tp record*/
struct addr *tpptr;
char *textptr;
{
    int p, cp, balloc();


    cp=strlen(textptr);

    if (!trail) {
        while (--cp >= 0 && isspace(textptr[cp]));
        textptr[++cp]='\0';
        }

    tpptr->moffset=p=balloc(1+cp);
    tpptr->page=newpage;
    strcpy(p+npaddr,textptr);
}

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], *t;
    int i, c, l;

    storehist=NO;
    while (lastread < line) {
        for (i=0, t=&txt[0]; i < LLIM && ((c=getc(textbuf)) >= ' ' ||
            c != '\n' && c != FAIL && c != ENDFILE); i++) {
                    if (c) *(t++)=c;
                else i--;
                }
        if (txt[i-1] == '\r') t--;
        *t='\0';
        if ( (l=inject(lastread,txt)) == FAIL) goto toomuch;
        else if ((lastread=l)%100 == 0) putlineno(lastread);
        if ( (goteof= c == ENDFILE || c == FAIL) )  goto eof;
        checkkey();
        }
    goto ok;
eof:
    fclose(textbuf);
toomuch:
    lastl=lastread;
ok:    storehist=YES;
}

opentext(name)    /*open the file being edited for reading*/
char *name;
{
    if (fopen(name,textbuf) == FAIL) {
        error("Can't open file");
        lastl=1;
        return FAIL;
        }
    return YES;
}

balloc(n)    /*allocate and return the offset in newpage of a vector size n*/
unsigned n;
{
    sint 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 != NULL) return;
    gotoxy(32,0);
    puts(errmess=message);
    resetcursor();
    inbufp=0;
}

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

    if(!storehist) return;

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

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

    if (!trail) {
        while (--cp >= 0 && isspace(textptr[cp]));
        textptr[++cp]='\0';
        }