added some useless shell commands

programs/vga_text_term/main.c

@@ -1,5 +1,8 @@
 #include <unistd.h>
 
+#define VGA_TEXT_W 80
+#define VGA_TEXT_H 25
+
 void term();
 
 int ptys;
@@ -30,15 +33,37 @@ int main(int argc, char *argv[]) {
     return 0;
 }
 
+void clear(int fd) {
+    lseek(fd, 0, 0);
+    size_t bytes = VGA_TEXT_W * VGA_TEXT_H;
+    char c = ' ';
+    for (size_t i = 0; i < bytes; i++) {
+        write(fd, &c, 1);
+    }
+    lseek(fd, 0, 0);
+}
+
 void term() {
     int vga_fd = open("/dev/tvga");
     if (vga_fd == -1) return;
 
+    int kbd_fd = open("/dev/kbd");
+    if (kbd_fd == -1) return;
+
+    clear(vga_fd);
+
+    char c;
     while (1) {
-        char c;
+        // first, get shell output
         int rd = read(0, &c, 1);
         if (rd > 0) {
             write(vga_fd, &c, 1);
         }
+
+        // then read a byte from the kbd. If we got one, pass it to the shell
+        rd = read(kbd_fd, &c, 1);
+        if (rd > 0) {
+            write(1, &c, 1);
+        }
     }
 }