Added some C2P documentation

include/libg1m/format/picture.h

@@ -11,7 +11,10 @@
 # define LIBG1M_FORMAT_PICTURE_H
 # include <stdint.h>
 
-/*	These are pictures for fx-CG. They only have one part.
+/* ************************************************************************** */
+/*  G3P: pictures for Prizm                                                   */
+/* ************************************************************************** */
+/*	G3P are pictures for fx-CG. They only have one part.
  *	This mysteries over this format have been unraveled by many, but I'm using
  *	Simon Lothar's documentation and Kerm Martian's articles.
  *
@@ -108,5 +111,65 @@ struct g3p_imagefooter {
 	uint32_t checksum;
 };
 
+/* ************************************************************************** */
+/*  C2P: Images for Classpads                                                 */
+/* ************************************************************************** */
+/*	C2P are images for fx-CP400 calculators. It starts of with this header: */
+
+struct c2p_subheader {
+	/* magic field: "CC0100" */
+	uint8_t magic1[6];
+
+	/* second magic: "ColorCP\0\0\0" */
+	uint8_t color_cp[10];
+
+	/* filesize without standard header */
+	uint32_t c2p_size;
+
+	/* unknown */
+	uint32_t unknown;
+
+	/* filesize - 0x234 */
+	uint32_t unknown_size;
+
+	/* undocumented */
+	uint8_t undocumented[124];
+
+	/* "0100" */
+	uint8_t zero_one_zero_zero[4];
+
+	/* filesize - 0x254 */
+	uint32_t unknown_size2;
+
+	/* unknown */
+	uint16_t unknown2;
+
+	/* width (max for screen: 0x136 */
+	uint16_t width;
+
+	/* height (max for screen: 0x191) */
+	uint16_t height;
+
+	/* undocumented, again */
+	uint8_t undocumented2[18];
+
+	/* filesize - 0x258 */
+	uint32_t unknown_size3;
+};
+
+/*	Then there is the zlib header with default compression.
+ *	The pixels format is R5G6B5.
+ *
+ *	After the image, there is a footer, which is mainly undocumented, but
+ *	here is what we've got: */
+
+struct c2p_footer {
+	/* "0100", again */
+	uint8_t zero_one_zero_zero[4];
+
+	/* and some undocumented stuff */
+	uint8_t undocumented[358];
+};
+
 # pragma pack()
 #endif /* LIBG1M_FORMAT_PICTURE_H */