103 lines
6.1 KiB
C
Executable File
103 lines
6.1 KiB
C
Executable File
//-----------------------------------------------------------------------------
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// Torque Game Engine
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// Copyright (C) GarageGames.com, Inc.
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//-----------------------------------------------------------------------------
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#ifndef _UNICODE_H_
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#define _UNICODE_H_
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#include "platform/types.h"
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/// Unicode conversion utility functions
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///
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/// Some definitions first:
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/// - <b>Code Point</b>: a single character of Unicode text. Used to disabmiguate from C char type.
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/// - <b>UTF-32</b>: a Unicode encoding format where one code point is always 32 bits wide.
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/// This format can in theory contain any Unicode code point that will ever be needed, now or in the future. 4billion+ code points should be enough, right?
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/// - <b>UTF-16</b>: a variable length Unicode encoding format where one code point can be
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/// either one or two 16-bit code units long.
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/// - <b>UTF-8</b>: a variable length Unicode endocing format where one code point can be
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/// up to four 8-bit code units long. The first bit of a single byte UTF-8 code point is 0.
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/// The first few bits of a multi-byte code point determine the length of the code point.
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/// @see http://en.wikipedia.org/wiki/UTF-8
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/// - <b>Surrogate Pair</b>: a pair of special UTF-16 code units, that encode a code point
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/// that is too large to fit into 16 bits. The surrogate values sit in a special reserved range of Unicode.
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/// - <b>Code Unit</b>: a single unit of a variable length Unicode encoded code point.
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/// UTF-8 has 8 bit wide code units. UTF-16 has 16 bit wide code units.
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/// - <b>BMP</b>: "Basic Multilingual Plane". Unicode values U+0000 - U+FFFF. This range
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/// of Unicode contains all the characters for all the languages of the world, that one would
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/// usually be interested in. All code points in the BMP are 16 bits wide or less.
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/// The current implementation of these conversion functions deals only with the BMP.
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/// Any code points above 0xFFFF, the top of the BMP, are replaced with the
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/// standard unicode replacement character: 0xFFFD.
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/// Any UTF16 surrogates are read correctly, but replaced.
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/// UTF-8 code points up to 6 code units wide will be read, but 5+ is illegal,
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/// and 4+ is above the BMP, and will be replaced.
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/// This means that UTF-8 output is clamped to 3 code units ( bytes ) per code point.
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//-----------------------------------------------------------------------------
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/// Functions that convert buffers of unicode code points, allocating a buffer.
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/// - These functions allocate their own return buffers. You are responsible for
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/// calling delete[] on these buffers.
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/// - Because they allocate memory, do not use these functions in a tight loop.
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/// - These are usefull when you need a new long term copy of a string.
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UTF16* convertUTF8toUTF16( const UTF8 *unistring);
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UTF32* convertUTF8toUTF32( const UTF8 *unistring);
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UTF8* convertUTF16toUTF8( const UTF16 *unistring);
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UTF32* convertUTF16toUTF32(const UTF16 *unistring);
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UTF8* convertUTF32toUTF8( const UTF32 *unistring);
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UTF16* convertUTF32toUTF16(const UTF32 *unistring);
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//-----------------------------------------------------------------------------
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/// Functions that convert buffers of unicode code points, into a provided buffer.
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/// - These functions are useful for working on existing buffers.
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/// - These cannot convert a buffer in place. If unistring is the same memory as
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/// outbuffer, the behavior is undefined.
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/// - The converter clamps output to the BMP (Basic Multilingual Plane) .
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/// - Conversion to UTF-8 requires a buffer of 3 bytes (U8's) per character, + 1.
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/// - Conversion to UTF-16 requires a buffer of 1 U16 (2 bytes) per character, + 1.
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/// - Conversion to UTF-32 requires a buffer of 1 U32 (4 bytes) per character, + 1.
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/// - UTF-8 only requires 3 bytes per character in the worst case.
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/// - Output is null terminated. Be sure to provide 1 extra byte, U16 or U32 for
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/// the null terminator, or you will see truncated output.
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/// - If the provided buffer is too small, the output will be truncated.
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const U32 convertUTF8toUTF16(const UTF8 *unistring, UTF16 *outbuffer, U32 len);
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const U32 convertUTF8toUTF32(const UTF8 *unistring, UTF32 *outbuffer, U32 len);
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const U32 convertUTF16toUTF8( const UTF16 *unistring, UTF8 *outbuffer, U32 len);
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const U32 convertUTF16toUTF32(const UTF16 *unistring, UTF32 *outbuffer, U32 len);
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const U32 convertUTF32toUTF8( const UTF32 *unistring, UTF8 *outbuffer, U32 len);
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const U32 convertUTF32toUTF16(const UTF32 *unistring, UTF16 *outbuffer, U32 len);
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//-----------------------------------------------------------------------------
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/// Functions that converts one unicode codepoint at a time
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/// - Since these functions are designed to be used in tight loops, they do not
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/// allocate buffers.
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/// - oneUTF8toUTF32() and oneUTF16toUTF32() return the converted Unicode code point
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/// in *codepoint, and set *unitsWalked to the \# of code units *codepoint took up.
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/// The next Unicode code point should start at *(codepoint + *unitsWalked).
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/// - oneUTF32toUTF8() requires a 3 byte buffer, and returns the \# of bytes used.
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const UTF32 oneUTF8toUTF32( const UTF8 *codepoint, U32 *unitsWalked = NULL);
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const UTF32 oneUTF16toUTF32(const UTF16 *codepoint, U32 *unitsWalked = NULL);
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const UTF16 oneUTF32toUTF16(const UTF32 codepoint);
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const U32 oneUTF32toUTF8( const UTF32 codepoint, UTF8 *threeByteCodeunitBuf);
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//-----------------------------------------------------------------------------
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/// Functions that calculate the length of unicode strings.
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/// - Since calculating the length of a UTF8 string is nearly as expensive as
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/// converting it to another format, a dStrlen for UTF8 is not provided here.
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/// - If *unistring does not point to a null terminated string of the correct type,
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/// the behavior is undefined.
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const U32 dStrlen(const UTF16 *unistring);
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const U32 dStrlen(const UTF32 *unistring);
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//-----------------------------------------------------------------------------
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/// Functions that scan for characters in a utf8 string.
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/// - this is useful for getting a character-wise offset into a UTF8 string,
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/// as opposed to a byte-wise offset into a UTF8 string: foo[i]
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const UTF8* getNthCodepoint(const UTF8 *unistring, const U32 n);
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#endif // _UNICODE_H_
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