* transcode.c: new file to provide encoding conversion features.

code contributed by Martin Duerst.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14172 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

transcode_data.h

@@ -0,0 +1,40 @@
+typedef unsigned char base_element;
+typedef const void * const info_element; 
+
+typedef struct byte_lookup {
+    const base_element *base;
+    const void * const * const info;
+} BYTE_LOOKUP;
+
+#ifdef TRANSCODE_DATA
+/* data file needs to treat this as a pointer, to remove warnings */
+#define PType (const void * const)
+#else
+/* in code, this is treated as just an integer */
+#define PType (int)
+#endif
+
+#define NOMAP   (PType 0x01)   /* single byte direct map */
+#define ONEbt   (0x02)   /* one byte payload */
+#define TWObt   (0x03)   /* two bytes payload */
+#define THREEbt (0x05)   /* three bytes payload */
+#define FOURbt  (0x06)   /* four bytes payload, UTF-8 only, macros start at getBT0 */
+#define ILLEGAL (PType 0x07)   /* illegal byte sequence */
+#define UNDEF   (PType 0x09)   /* legal but undefined */
+#define ZERObt  (PType 0x0A)   /* zero bytes of payload, i.e. remove */
+
+#define output1(b1)          ((void*)((((unsigned char)(b1))<<8)|ONEbt))
+#define output2(b1,b2)       ((void*)((((unsigned char)(b1))<<8)|(((unsigned char)(b2))<<16)|TWObt))
+#define output3(b1,b2,b3)    ((void*)((((unsigned char)(b1))<<8)|(((unsigned char)(b2))<<16)|(((unsigned char)(b3))<<24)|THREEbt))
+#define output4(b0,b1,b2,b3) ((void*)((((unsigned char)(b1))<< 8)|(((unsigned char)(b2))<<16)|(((unsigned char)(b3))<<24)|((((unsigned char)(b0))&0x07)<<5)|FOURbt))
+
+#define getBT1(a)      (((a)>> 8)&0xFF)
+#define getBT2(a)      (((a)>>16)&0xFF)
+#define getBT3(a)      (((a)>>24)&0xFF)
+#define getBT0(a)      ((((a)>> 5)&0x07)|0xF0)   /* for UTF-8 only!!! */
+
+/* do we need these??? maybe not, can be done with simple tables */
+#define ONETRAIL       /* legal but undefined if one more trailing UTF-8 */
+#define TWOTRAIL       /* legal but undefined if two more trailing UTF-8 */
+#define THREETRAIL     /* legal but undefined if three more trailing UTF-8 */
+