experiments with vt100 scrolling

scrolling.c

/* vim:ts=2:sw=2:expandtab
 */
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>

struct termios orig_termios;

void die(const char *s) {
  perror(s);
  exit(1);
}
// from Kilo
void disableRawMode() {
  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios) == -1)
    die("tcsetattr");
}

// from Kilo
void enableRawMode() {
  if (tcgetattr(STDIN_FILENO, &orig_termios) == -1)
    die("tcgetattr");
  atexit(disableRawMode);
  struct termios raw = orig_termios;
  raw.c_iflag &= ~(/*BRKINT |*/ ICRNL | INPCK | ISTRIP | IXON);
  raw.c_oflag &= ~(OPOST);
  raw.c_cflag |= (CS8);
  raw.c_lflag &= ~(ECHO | ICANON | IEXTEN /*| ISIG*/);
  raw.c_cc[VMIN] = 0;
  raw.c_cc[VTIME] = 1;
  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1)
    die("tcsetattr");
}

void statusline(void) {
  printf("-- STATUS LINE --\r\eE");
  fflush(stdout);
}

// featuring learning from http://ascii-table.com/ansi-escape-sequences-vt-100.php
void main(int c, char **v) {
  char cc;
  enableRawMode();
  atexit(disableRawMode);
  printf("\e[2J");
  for(int i = 0; i < 16; i++)
    printf("\eE");
  fflush(stdout);
  statusline();
  for(int q = 0;; q++) {
    usleep(500000);
    char *newcontent = "NEW CONTENT IS HERE! %d";
    printf("\eE"); // new blank
    printf("\eM"); // old blank
    printf("\eM"); // old status line
    printf("\e[K"); // blank it
    printf(newcontent, q);
    printf("\r\eE"); // start of status area
    statusline();
  }
}