+#include <stddef.h> /* Surprisingly, the only symbol needed is NULL */
#include "glk.h"
/* Version of the Glk specification implemented by this library */
* @sel: A selector, representing which capability to request information
* about.
* @val: Extra information, depending on the value of @sel.
- * @arr: Location of an array to store extra information in, or #NULL.
- * @arrlen: Length of @arr, or 0 if @arr is #NULL.
+ * @arr: Location of an array to store extra information in, or %NULL.
+ * @arrlen: Length of @arr, or 0 if @arr is %NULL.
*
- * Calls the gestalt system to request information about selector @sel,
- * possibly returning information in @arr.
+ * Calls the gestalt system to request information about the capabilities of the
+ * API. The selector @sel tells which capability you are requesting information
+ * about; the other three arguments are additional information, which may or may
+ * not be meaningful. The @arr and @arrlen arguments of glk_gestalt_ext() are
+ * always optional; you may always pass %NULL and 0, if you do not want whatever
+ * information they represent. glk_gestalt() is simply a shortcut for this;
+ * <code>#glk_gestalt(x, y)</code> is exactly the same as
+ * <code>#glk_gestalt_ext(x, y, %NULL, 0)</code>.
+ *
+ * The critical point is that if the Glk library has never heard of the selector
+ * @sel, it will return 0. It is <emphasis>always</emphasis> safe to call
+ * <code>#glk_gestalt(x, y)</code> (or <code>#glk_gestalt_ext(x, y, %NULL,
+ * 0)</code>). Even if you are using an old library, which was compiled before
+ * the given capability was imagined, you can test for the capability by calling
+ * glk_gestalt(); the library will correctly indicate that it does not support
+ * it, by returning 0.
+ *
+ * (It is also safe to call <code>#glk_gestalt_ext(x, y, z, zlen)</code> for an
+ * unknown selector <code>x</code>, where <code>z</code> is not %NULL, as long
+ * as <code>z</code> points at an array of at least <code>zlen</code> elements.
+ * The selector will be careful not to write beyond that point in the array, if
+ * it writes to the array at all.)
+ *
+ * (If a selector does not use the second argument, you should always pass 0; do
+ * not assume that the second argument is simply ignored. This is because the
+ * selector may be extended in the future. You will continue to get the current
+ * behavior if you pass 0 as the second argument, but other values may produce
+ * other behavior.)
*
* Returns: an integer, depending on what selector was called.
*/
{
/* Version number */
case gestalt_Version:
- return MAJOR_VERSION << 16 + MINOR_VERSION << 8 + SUB_VERSION;
+ return (MAJOR_VERSION << 16) + (MINOR_VERSION << 8) + SUB_VERSION;
+
+ /* Which characters can the player type in line input? */
+ case gestalt_LineInput:
+ /* Does not accept control chars */
+ if( val < 32 || (val >= 127 && val <= 159) )
+ return 0;
+ return 1;
+
+ /* Which characters can the player type in char input? */
+ case gestalt_CharInput:
+ /* Does not accept control chars or unknown */
+ if( val < 32 || (val >= 127 && val <= 159) || val == keycode_Unknown )
+ return 0;
+ return 1;
/* Which characters can we print? */
case gestalt_CharOutput:
return gestalt_CharOutput_CannotPrint;
/* Can print all other Latin-1 characters */
return gestalt_CharOutput_ExactPrint;
+
+ /* Unicode capabilities present */
+ case gestalt_Unicode:
+ return 1;
+
+ /* Timer capabilities present */
+ case gestalt_Timer:
+ return 1;
+ /* Unsupported capabilities */
+ case gestalt_MouseInput:
+ case gestalt_Graphics:
+ case gestalt_DrawImage:
+ case gestalt_Sound:
+ case gestalt_SoundVolume:
+ case gestalt_SoundNotify:
+ case gestalt_Hyperlinks:
+ case gestalt_HyperlinkInput:
+ case gestalt_SoundMusic:
+ case gestalt_GraphicsTransparency:
/* Selector not supported */
default:
return 0;