PDCLIB-12: Groundwork for encoding support system

diff --git a/internals/_PDCLIB_encoding.h b/internals/_PDCLIB_encoding.h
new file mode 100644 (file)
index 0000000..81e6a9e
--- /dev/null
+++ b/internals/_PDCLIB_encoding.h
@@ -0,0 +1,140 @@
+/* Encoding support <_PDCLIB_encoding.h>
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#ifndef _PDCLIB_ENCODING_H
+#define _PDCLIB_ENCODING_H _PDCLIB_ENCODING_H
+#include "_PDCLIB_int.h"
+
+#ifndef __cplusplus
+typedef _PDCLIB_int_least16_t   _PDCLIB_char16_t;
+typedef _PDCLIB_int_least32_t   _PDCLIB_char32_t;
+#else
+typedef char16_t                _PDCLIB_char16_t;
+typedef char32_t                _PDCLIB_char32_t;
+#endif
+
+#ifdef _PDCLIB_WCHAR_IS_UCS2
+/* Must be cauued with bufsize >= 1, in != NULL, out != NULL, ps != NULL
+ *
+ * Converts a wchar to a UCS4 (char32_t) value. Returns
+ *   1, 2   : Valid character (converted to UCS-4)
+ *   -1     : Encoding error
+ *   -2     : Partial character (only lead surrogate in buffer)
+ */
+static inline int _PDCLIB_wcrtoc32(
+            _PDCLIB_char32_t    *_PDCLIB_restrict   out, 
+    const   _PDCLIB_wchar_t     *_PDCLIB_restrict   in,
+            _PDCLIB__PDCLIB_size_t                          bufsize,
+            _PDCLIB_mbstate_t   *_PDCLIB_restrict   ps  
+)
+{
+    if(ps->_Surrogate) {
+        // We already have a lead surrogate
+        if(*in & ~0x3FF != 0xDC00) {
+            // Encoding error
+            return -1;
+        } else {
+            // Decode and reset state
+            *out = (ps->_Surrogate & 0x3FF) << 10 | (*in & 0x3FF);
+            ps->_Surrogate = 0;
+            return 1;
+        }
+    } if(*in & ~0x3FF == 0xD800) {
+        // Lead surrogate
+        if(bufsize >= 2) {
+            // Buffer big enough
+            if(in[1] & ~0x3FF != 0xDC00) {
+                // Encoding error
+                return -1;
+            } else {
+                *out = (in[0] & 0x3FF) << 10 | (in[1] & 0x3FF);
+                return 2;
+            }
+        } else {
+            // Buffer too small - update state
+            ps->_Surrogate = *in;
+            return -2;
+        }
+    } else {
+        // BMP character
+        *out = *in;
+        return 1;
+    }
+}
+
+static inline _PDCLIB_size_t _PDCLIB_c32rtowc(
+            _PDCLIB_wchar_t     *_PDCLIB_restrict   out,
+    const   _PDCLIB_char32_t    *_PDCLIB_restrict   in,
+            _PDCLIB__PDCLIB_size_t                          bufsize,
+            _PDCLIB_mbstate_t   *_PDCLIB_restrict   ps
+)
+{
+    if(ps->_Surrogate) {
+        *out = ps->_Surrogate;
+        ps->_Surrogate = 0;
+        return 0;
+    }
+
+    if(*in <= 0xFFFF) {
+        // BMP character
+        *out = *in;
+        return 1;
+    } else {
+        // Supplementary plane character
+        *out = 0xD800 | (*in & 0x3FF);
+        if(bufsize >= 2) {
+            out[1] = 0xDC00 | (*in >> 10);
+            return 2;
+        } else {
+            ps->_Surrogate = 0xDC00 | (*in >> 10);
+            return 1;
+        }
+    }
+}
+#else
+/* Dummy implementation for when wc == c32 */
+static inline _PDCLIB_size_t _PDCLIB_wcrtoc32(
+            _PDCLIB_char32_t    *_PDCLIB_restrict   out, 
+    const   _PDCLIB_wchar_t     *_PDCLIB_restrict   in,
+            _PDCLIB__PDCLIB_size_t                          bufsize,
+            _PDCLIB_mbstate_t   *_PDCLIB_restrict   ps  
+)
+{
+    *out = *in;
+    return 1;
+}
+
+static inline _PDCLIB_size_t _PDCLIB_c32rtowc(
+            _PDCLIB_wchar_t     *_PDCLIB_restrict   out,
+    const   _PDCLIB_char32_t    *_PDCLIB_restrict   in,
+            _PDCLIB__PDCLIB_size_t                          bufsize,
+            _PDCLIB_mbstate_t   *_PDCLIB_restrict   ps
+)
+{
+    *out = *in;
+    return 1;
+}
+#endif
+
+typedef struct {
+    _PDCLIB_bool_t (*__mbtoc32)(
+        _PDCLIB_char32_t       **_PDCLIB_restrict   _P_outbuf,
+        _PDCLIB_size_t          *_PDCLIB_restrict   _P_outsz,
+        const char             **_PDCLIB_restrict   _P_inbuf,
+        _PDCLIB_size_t          *_PDCLIB_restrict   _P_insz,
+        _PDCLIB_mbstate_t       *_PDCLIB_restrict   _P_ps
+    );
+
+    _PDCLIB_bool_t (*__c32tomb)(
+        char                   **_PDCLIB_restrict  _P_outbuf,
+        _PDCLIB_size_t          *_PDCLIB_restrict  _P_outsz,
+        const _PDCLIB_char32_t **_PDCLIB_restrict  _P_inbuf,
+        _PDCLIB_size_t          *_PDCLIB_restrict  _P_insz,
+        _PDCLIB_mbstate_t       *_PDCLIB_restrict  _P_ps
+    );
+} _PDCLIB_charcodec;
+
+#endif