feature: Windows support for winsize (#4)

Signed-off-by: Ali Caglayan <[email protected]>

src-unix/native/winsize.c

@@ -1,7 +1,7 @@
 #include <caml/mlvalues.h>
 
 #ifdef _WIN32
-#include <caml/fail.h>
+#include <windows.h>
 #else
 #include <sys/ioctl.h>
 #include <signal.h>
@@ -15,7 +15,16 @@
 CAMLprim value caml_notty_winsize (value vfd) {
 #ifdef _WIN32
   (void) vfd;
-  caml_failwith("not implemented on windows");
+  HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
+  if (hConsole == INVALID_HANDLE_VALUE) return Val_int (0);
+
+  CONSOLE_SCREEN_BUFFER_INFO csbi;
+  if (GetConsoleScreenBufferInfo(hConsole, &csbi)) {
+    int columns = csbi.srWindow.Right - csbi.srWindow.Left + 1;
+    int rows = csbi.srWindow.Bottom - csbi.srWindow.Top + 1;
+    return Val_int ((columns << 16) + ((rows & 0x7fff) << 1));
+  } 
+  return Val_int (0);
 #else
   int fd = Int_val (vfd);
   struct winsize w;