Add CJK codecs support as discussed on python-dev. (SF #873597)

Several style fixes are suggested by Martin v. Loewis and
Marc-Andre Lemburg. Thanks!
diff --git a/Modules/cjkcodecs/codeccommon.h b/Modules/cjkcodecs/codeccommon.h
new file mode 100644
index 0000000..f66d892
--- /dev/null
+++ b/Modules/cjkcodecs/codeccommon.h
@@ -0,0 +1,144 @@
+/*
+ * codeccommon.h: Common Codec Routines
+ *
+ * Written by Hye-Shik Chang <perky@FreeBSD.org>
+ * $CJKCodecs: codeccommon.h,v 1.4 2003/12/31 05:46:55 perky Exp $
+ */
+
+#include "Python.h"
+#include "multibytecodec.h"
+
+
+#ifdef STRICT_BUILD
+#define STRICT_SUFX     "_strict"
+#else
+#define STRICT_SUFX
+#endif
+
+#define ENCMAP(encoding)                                    \
+    const static encode_map *encoding##encmap;
+#define DECMAP(encoding)                                    \
+    const static decode_map *encoding##decmap;
+
+#define ENCODER_INIT(encoding)                              \
+    static int encoding##_encode_init(                      \
+        MultibyteCodec_State *state)
+#define ENCODER(encoding)                                   \
+    static int encoding##_encode(                           \
+        MultibyteCodec_State *state,                        \
+        const Py_UNICODE **inbuf, size_t inleft,            \
+        unsigned char **outbuf, size_t outleft, int flags)
+#define ENCODER_RESET(encoding)                             \
+    static int encoding##_encode_reset(                     \
+        MultibyteCodec_State *state,                        \
+        unsigned char **outbuf, size_t outleft)
+
+#define DECODER_INIT(encoding)                              \
+    static int encoding##_decode_init(                      \
+        MultibyteCodec_State *state)
+#define DECODER(encoding)                                   \
+    static int encoding##_decode(                           \
+        MultibyteCodec_State *state,                        \
+        const unsigned char **inbuf, size_t inleft,         \
+        Py_UNICODE **outbuf, size_t outleft)
+#define DECODER_RESET(encoding)                             \
+    static int encoding##_decode_reset(                     \
+        MultibyteCodec_State *state)
+
+#if Py_UNICODE_SIZE == 4
+#define UCS4INVALID(code)                                   \
+    if ((code) > 0xFFFF)                                    \
+        return 1;
+#else
+#define UCS4INVALID(code)                                   \
+    if (0) ;
+#endif
+
+#define NEXT_IN(i)                                          \
+    (*inbuf) += (i);                                        \
+    (inleft) -= (i);
+#define NEXT_OUT(o)                                         \
+    (*outbuf) += (o);                                       \
+    (outleft) -= (o);
+#define NEXT(i, o)  NEXT_IN(i) NEXT_OUT(o)
+
+#define RESERVE_INBUF(n)                                    \
+    if (inleft < (n))                                       \
+        return MBERR_TOOFEW;
+#define RESERVE_OUTBUF(n)                                   \
+    if (outleft < (n))                                      \
+        return MBERR_TOOSMALL;
+
+#define IN1 ((*inbuf)[0])
+#define IN2 ((*inbuf)[1])
+#define IN3 ((*inbuf)[2])
+#define IN4 ((*inbuf)[3])
+
+#define OUT1(c) ((*outbuf)[0]) = (c);
+#define OUT2(c) ((*outbuf)[1]) = (c);
+#define OUT3(c) ((*outbuf)[2]) = (c);
+#define OUT4(c) ((*outbuf)[3]) = (c);
+
+#define WRITE1(c1)                                          \
+    RESERVE_OUTBUF(1)                                       \
+    (*outbuf)[0] = (c1);
+#define WRITE2(c1, c2)                                      \
+    RESERVE_OUTBUF(2)                                       \
+    (*outbuf)[0] = (c1);                                    \
+    (*outbuf)[1] = (c2);
+#define WRITE3(c1, c2, c3)                                  \
+    RESERVE_OUTBUF(3)                                       \
+    (*outbuf)[0] = (c1);                                    \
+    (*outbuf)[1] = (c2);                                    \
+    (*outbuf)[2] = (c3);
+#define WRITE4(c1, c2, c3, c4)                              \
+    RESERVE_OUTBUF(4)                                       \
+    (*outbuf)[0] = (c1);                                    \
+    (*outbuf)[1] = (c2);                                    \
+    (*outbuf)[2] = (c3);                                    \
+    (*outbuf)[3] = (c4);
+
+#if Py_UNICODE_SIZE == 2
+# define PUTUCS4(c)                                         \
+    RESERVE_OUTBUF(2)                                       \
+    (*outbuf)[0] = 0xd800 + (((c) - 0x10000) >> 10);        \
+    (*outbuf)[1] = 0xdc00 + (((c) - 0x10000) & 0x3ff);      \
+    NEXT_OUT(2)
+#else
+# define PUTUCS4(c)                                         \
+    RESERVE_OUTBUF(1)                                       \
+    **outbuf = (Py_UNICODE)(c);                             \
+    NEXT_OUT(1)
+#endif
+
+#define _TRYMAP_ENC(m, assi, val)                           \
+    if ((m)->map != NULL && (val) >= (m)->bottom &&         \
+        (val)<= (m)->top && ((assi) = (m)->map[(val) -      \
+            (m)->bottom]) != NOCHAR)
+#define TRYMAP_ENC(charset, assi, uni)                      \
+    _TRYMAP_ENC(&charset##encmap[(uni) >> 8], assi, (uni) & 0xff)
+#define _TRYMAP_DEC(m, assi, val)                           \
+    if ((m)->map != NULL && (val) >= (m)->bottom &&         \
+        (val)<= (m)->top && ((assi) = (m)->map[(val) -      \
+            (m)->bottom]) != UNIINV)
+#define TRYMAP_DEC(charset, assi, c1, c2)                   \
+    _TRYMAP_DEC(&charset##decmap[c1], assi, c2)
+
+#if Py_UNICODE_SIZE == 2
+#define DECODE_SURROGATE(c)                                 \
+    if (c >> 10 == 0xd800 >> 10) { /* high surrogate */     \
+        RESERVE_INBUF(2)                                    \
+        if (IN2 >> 10 == 0xdc00 >> 10) { /* low surrogate */ \
+            c = 0x10000 + ((ucs4_t)(c - 0xd800) << 10) +    \
+                          ((ucs4_t)(IN2) - 0xdc00);         \
+        }                                                   \
+    }
+#define GET_INSIZE(c)   ((c) > 0xffff ? 2 : 1)
+#else
+#define DECODE_SURROGATE(c) {;}
+#define GET_INSIZE(c)   1
+#endif
+
+#ifdef USING_BINARY_PAIR_SEARCH
+static DBCHAR find_pairencmap(ucs2_t , ucs2_t, struct pair_encodemap *, int);
+#endif