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copied!<p>Here's some sample code which:</p> <ol> <li><p>Performs dynamic memory allocation.</p></li> <li><p>Reads from the console in non-blocking mode.</p></li> <li><p>Uses VT100 codes to print a frame buffer to the console.</p></li> </ol> <p>It compiles on Linux using GCC without warnings or errors. It's far from bug free, but it should give you some ideas of what's possible. Compile and run it, pressing [up] and [down] will print messages, typing characters and hitting [enter] will "execute" the command. </p> <pre><code>#include <poll.h> #include <signal.h> #include <stdio.h> #include <termios.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <time.h> /** VT100 command to clear the screen. Use puts(VT100_CLEAR_SCREEN) to clear * the screen. */ #define VT100_CLEAR_SCREEN "\033[2J" /** VT100 command to reset the cursor to the top left hand corner of the * screen. */ #define VT100_CURSOR_TO_ORIGIN "\033[H" struct frame_s { int x; int y; char *data; }; static int draw_frame(struct frame_s *frame) { int row; char *data; int attrib; puts(VT100_CLEAR_SCREEN); puts(VT100_CURSOR_TO_ORIGIN); for (row = 0, data = frame->data; row < frame->y; row++, data += frame->x) { /* 0 for normal, 1 for bold, 7 for reverse. */ attrib = 0; /* The VT100 commands to move the cursor, set the attribute, and the * actual frame line. */ fprintf(stdout, "\033[%d;%dH\033[0m\033[%dm%.*s", row + 1, 0, attrib, frame->x, data); fflush(stdout); } return (0); } int main(void) { const struct timespec timeout = { .tv_sec = 1, .tv_nsec = 0 }; struct frame_s frame; struct termios tty_old; struct termios tty_new; unsigned char line[128]; unsigned int count = 0; int ret; struct pollfd fds[1]; sigset_t sigmask; struct tm *tp; time_t current_time; /* Set up a little frame. */ frame.x = 80; frame.y = 5; frame.data = malloc(frame.x * frame.y); if (frame.data == NULL) { fprintf(stderr, "No memory\n"); exit (1); } memset(frame.data, ' ', frame.x * frame.y); /* Get the terminal state. */ tcgetattr(STDIN_FILENO, &tty_old); tty_new = tty_old; /* Turn off "cooked" mode (line buffering) and set minimum characters * to zero (i.e. non-blocking). */ tty_new.c_lflag &= ~ICANON; tty_new.c_cc[VMIN] = 0; /* Set the terminal attributes. */ tcsetattr(STDIN_FILENO, TCSANOW, &tty_new); /* Un-mask all signals while in ppoll() so any signal will cause * ppoll() to return prematurely. */ sigemptyset(&sigmask); fds[0].events = POLLIN; fds[0].fd = STDIN_FILENO; /* Loop forever waiting for key presses. Update the output on every key * press and every 1.0s (when ppoll() times out). */ do { fds[0].revents = 0; ret = ppoll(fds, sizeof(fds) / sizeof(struct pollfd), &timeout, &sigmask); if (fds[0].revents & POLLIN) { ret = read(STDIN_FILENO, &line[count], sizeof(line) - count); if (ret > 0) { line[count + ret] = '\0'; if (strcmp(&line[count], "\033[A") == 0) { snprintf(frame.data, frame.x, "up"); count = 0; } else if (strcmp(&line[count], "\033[B") == 0) { snprintf(frame.data, frame.x, "down"); count = 0; } else if (line[count] == 127) // backspace { if (count != 0) { count -= ret;} } else if (line[count] == '\n') { snprintf(frame.data, frame.x, "entered: %s", line); count = 0; } else { count += ret; } } } /* Print the current time to the output buffer. */ current_time = time(NULL); tp = localtime(&current_time); strftime(&frame.data[1 * frame.x], frame.x, "%Y/%m/%d %H:%M:%S", tp); /* Print the command line. */ line[count] = '\0'; snprintf(&frame.data[(frame.y - 1) * frame.x], frame.x, "$ %s", line); draw_frame(&frame); } while (1); /* Restore terminal and free resources. */ tcsetattr(STDIN_FILENO, TCSANOW, &tty_old); free(frame.data); return (0); } </code></pre>

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