README

This is a repro case in Rust and a (rough) equivalent in C for this issue:

https://github.com/tomassedovic/tcod-rs/issues/54

Download `libtcod-1.5.2-mingw32.tar.gz` from `http://roguecentral.org/doryen/libtcod/download/` and unpack `SDL.dll`, `libtcod-mingw.dll` and `terminal.png` to the same directory as the `key.rs` and `key.c` files. And you'll probably have to create a copy of `libtcod-mingw.dll` called `libtcod.dll`.

To build & run the Rust code:

    rustc key.rs -o key_rs && key_rs

Build & run the C code:

    mingw32-gcc key.c -ltcod -L . -o key_c && key_c

key.c

#include "stdio.h"

typedef char bool;

typedef enum {
	TCOD_RENDERER_GLSL,
	TCOD_RENDERER_OPENGL,
	TCOD_RENDERER_SDL,
	TCOD_NB_RENDERERS,
} TCOD_renderer_t;

typedef struct {
	int vk;
	char c;
	bool pressed;
	bool lalt;
	bool lctrl;
	bool ralt;
	bool rctrl;
	bool shift;
} TCOD_key_t;


void TCOD_console_init_root(int w, int h, const char * title, bool fullscreen, TCOD_renderer_t renderer);
bool TCOD_console_is_window_closed();
void TCOD_console_flush();
TCOD_key_t TCOD_console_wait_for_keypress(bool flush);


int main() {
	TCOD_console_init_root(80, 50, "tcod window", 0, 2);
	while (TCOD_console_is_window_closed() == 0) {
		TCOD_console_flush();
		TCOD_key_t key = TCOD_console_wait_for_keypress(1);
		char* c = (char*)&key;
		int i;
		printf("TCOD_key_t:\n");
		for(i = 0; i < 12; i++) {
			printf("%d, ", c[i]);
		}
		printf("\n");

		// NOTE: the `vk` value appears to be hidding negative four bytes from
		// the beginning of the `TCOD_key_t` struct:
		printf("TCOD_key_t - 4 bytes:\n");
		for(i = -4; i < 8; i++) {
			printf("%d, ", c[i]);
		}
		printf("\n---\n");
	}
	return(0);
}

key.rs

extern crate libc;

use libc::{c_int, c_uint, c_char, c_uchar};


#[link(name = "tcod")]
extern "C" {
    pub fn TCOD_console_init_root(w: c_int, h: c_int,
                                  title: *const c_char,
                                  fullscreen: c_uchar,
                                  renderer: c_uint);
    pub fn TCOD_console_is_window_closed() -> c_uchar;
    pub fn TCOD_console_flush();
    pub fn TCOD_console_wait_for_keypress(flush: c_uchar) -> TCOD_key_t;
}

#[deriving(Show, Copy)]
#[repr(C)]
pub struct TCOD_key_t {
    // NOTE: if you comment `vk` out, you stop getting bogus values:
    pub vk: c_int,
    pub c: c_char,
    pub pressed: c_uchar,
    pub lalt: c_uchar,
    pub lctrl: c_uchar,
    pub ralt: c_uchar,
    pub rctrl: c_uchar,
    pub shift: c_uchar,
}

fn main() {
    unsafe {
        "tcod window".with_c_str(|s| TCOD_console_init_root(80, 50, s, 0, 2));
        while TCOD_console_is_window_closed() == 0 {
            TCOD_console_flush();
            let key = TCOD_console_wait_for_keypress(1);
            // NOTE: if you comment this out, weird stuf happens (segfaults or
            // always returning the same values for key no matter what's pressed):
            println!("wtf?");

            println!("k: {}", key);
        }
    }
}