NAME

       keyboard_lowlevel_callback - User specified low level keyboard event handler. Allegro game
       programming library.

SYNOPSIS

       #include <allegro.h>

       extern void (*keyboard_lowlevel_callback)(int scancode);

DESCRIPTION

       If set, this function is called by the keyboard handler  in  response  to  every  keyboard
       event, both presses (including keyboard repeat rate) and releases. It will be passed a raw
       keyboard scancode byte (scancodes are 7 bits long), with the top bit (8th  bit)  clear  if
       the  key has been pressed or set if it was released. This routine executes in an interrupt
       context, so it must be in locked memory. Example:

          volatile int key_down, key_up;

          void keypress_watcher(int scancode)
          {
             if (scancode & 0x80) {
                key_up = 1;
             } else {
                key_down = 1;
             }
          } END_OF_FUNCTION(keypress_watcher)

          ...

             install_timer();
             LOCK_FUNCTION(silence_g_key);
             LOCK_VARIABLE(key_down);
             LOCK_VARIABLE(key_up);
             install_keyboard();
             keyboard_lowlevel_callback = keypress_watcher;
             /* Disable keyboard repeat to get typewriter effect. */
             set_keyboard_rate(0, 0);

          ...

             while (game_loop) {
                if (key_down) {
                   key_down = 0;
                   /* Play sample of typewriter key press. */
                }
                if (key_up) {
                   key_up = 0;
                   /* Play sample of typewriter key release. */
                }
             }

SEE ALSO

       install_keyboard(3alleg4),    keyboard_callback(3alleg4),     keyboard_ucallback(3alleg4),
       exkeys(3alleg4)