Bell 32V development

[unix-history] / usr / src / cmd / pg.c

#include <stdio.h>

#define NL '\n'
#define CLEAR 014
#define HOME 031
#define BACK 037
#define BUFMAX 16384
#define PAGMAX 64

int file;
int cp, hp;
int page[PAGMAX];
int eof;

char buf[BUFMAX];
int bptr, bnxt, bend;


#define incr(a,b) (a++, a&=b-1)
#define decr(a,b) (a--, a&=b-1)


main(argc,argv)
char *argv[];
{
       int n=1;
       if(argc<2)
               print();
       else {
               while(argv[n]!=-1) {
                       if((file=open(argv[n],0))>=0) {
                               print();
                               close(file);
                       } else  printf("dk: `%s' cannot open\n",argv[n]);
                       n++;
               }
       }
}

print()
{
       register int nlc;
       char buf[2];

       hp=0; cp=0;
       bptr=bnxt=bend=0;
       putchar(CLEAR);
       for(;;) {
               setpage();
               nlc=0;
               putchar(BACK);
               while(nlc<20) {
                       char c;
                       c = readchar();
                       if(eof)
                               return;
                       if(c==NL) nlc++;
                       putchar(c);
               }
               while(read(2,buf,1)==1 && buf[0]!=NL) {
                       switch(buf[0]) {
                               case '/':
                               case HOME:
                                       putchar(CLEAR);
                                       getpage(0);
                                       break;
                               case '-':
                               case BACK:
                                       getpage(-1);
                                       putchar(CLEAR);
                                       break;
                               case '!':
                                       shell(); buf[0]=NL; break;
                       }
               }
       }
}


#include <signal.h>
#define EOR '\n'
shell()
{
       int rc, status, unixpid;
       if( (unixpid=fork())==0 ) {
               close(0); dup(2);
               execl("/bin/sh", "sh", "-t", 0);
               exit(255);
       }
       else if(unixpid == -1)
               return(0);
       else{   signal(SIGINT,SIG_IGN); signal(SIGQUIT,SIG_IGN);
               while( (rc = wait(&status)) != unixpid && rc != -1 ) ;
               signal(SIGINT,SIG_DFL); signal(SIGQUIT,SIG_DFL);
               return(1);
       }
}

readchar()
{
       register char c;
       if(bnxt==bend)
               fillbuf();
       if(eof)
               return(-1);
       c=buf[bnxt];
       incr(bnxt,BUFMAX);
       return(c);
}

fillbuf()
{
       register int r;
       register int len;
       ensure();
       if(eof)
               return;
       r=read(file,&buf[bend],512);
       if(r==-1)
               return;
       bend += r; bend &= BUFMAX-1;
       if(r==0)
               eof++;
       return;
}

ensure()
{
       for(;;) {
               if(bptr<=bend)
                       return(BUFMAX-bend-1);
               if(bptr-bend>=512)
                       return(512);
               losepage();
       }
}

losepage()
{
       if(hp<cp)
               bptr=page[incr(hp,PAGMAX)];
}

setpage()
{
       incr(cp,PAGMAX);
       if(cp==hp)
               incr(hp,PAGMAX);
       page[cp]=bnxt;
}

getpage(i)
{
       if(i==0)
               cp=hp;
       else    if(cp!=hp)
                       decr(cp,PAGMAX);
       bnxt=page[cp];
}