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#ifndef SLANG_CORE_CHAR_ENCODE_H
#define SLANG_CORE_CHAR_ENCODE_H
#include "slang-basic.h"
#include "slang-secure-crt.h"
namespace Slang
{
// NOTE! Order must be kept the same to match up with
enum class CharEncodeType
{
UTF8,
UTF16,
UTF16Reversed,
UTF32,
CountOf,
};
template<typename ReadByteFunc>
Char32 getUnicodePointFromUTF8(const ReadByteFunc& readByte)
{
Char32 codePoint = 0;
uint32_t leading = uint32_t(readByte());
uint32_t mask = 0x80;
Index count = 0;
while (leading & mask)
{
count++;
mask >>= 1;
}
codePoint = (leading & (mask - 1));
for (Index i = 1; i <= count - 1; i++)
{
codePoint <<= 6;
codePoint += (readByte() & 0x3F);
}
return codePoint;
}
template<typename ReadByteFunc>
Char32 getUnicodePointFromUTF16(const ReadByteFunc& readByte)
{
uint32_t byte0 = Byte(readByte());
uint32_t byte1 = Byte(readByte());
uint32_t word0 = byte0 + (byte1 << 8);
if (word0 >= 0xD800 && word0 <= 0xDFFF)
{
uint32_t byte2 = Byte(readByte());
uint32_t byte3 = Byte(readByte());
uint32_t word1 = byte2 + (byte3 << 8);
return Char32(((word0 & 0x3FF) << 10) + (word1 & 0x3FF) + 0x10000);
}
else
return Char32(word0);
}
template<typename ReadByteFunc>
Char32 getUnicodePointFromUTF16Reversed(const ReadByteFunc& readByte)
{
uint32_t byte0 = Byte(readByte());
uint32_t byte1 = Byte(readByte());
uint32_t word0 = (byte0 << 8) + byte1;
if (word0 >= 0xD800 && word0 <= 0xDFFF)
{
uint32_t byte2 = Byte(readByte());
uint32_t byte3 = Byte(readByte());
uint32_t word1 = (byte2 << 8) + byte3;
return Char32(((word0 & 0x3FF) << 10) + (word1 & 0x3FF));
}
else
return Char32(word0);
}
template<typename ReadByteFunc>
Char32 getUnicodePointFromUTF32(const ReadByteFunc& readByte)
{
uint32_t byte0 = Byte(readByte());
uint32_t byte1 = Byte(readByte());
uint32_t byte2 = Byte(readByte());
uint32_t byte3 = Byte(readByte());
return Char32(byte0 + (byte1 << 8) + (byte2 << 16) + (byte3 << 24));
}
// Encode functions return the amount of elements output to the buffer
inline int encodeUnicodePointToUTF8(Char32 codePoint, char* outBuffer)
{
char* const dst = outBuffer;
// TODO(JS): This supports 4 + 6 * 3 = 22 bits.
// The standard allows up to 0x10FFFF.
if (codePoint <= 0x7F)
{
dst[0] = char(codePoint);
return 1;
}
else if (codePoint <= 0x7FF)
{
dst[0] = char(0xC0 + (codePoint >> 6));
dst[1] = char(0x80 + (codePoint & 0x3F));
return 2;
}
else if (codePoint <= 0xFFFF)
{
dst[0] = char(0xE0 + (codePoint >> 12));
dst[1] = char(0x80 + ((codePoint >> 6) & (0x3F)));
dst[2] = char(0x80 + (codePoint & 0x3F));
return 3;
}
else
{
dst[0] = char(0xF0 + (codePoint >> 18));
dst[1] = char(0x80 + ((codePoint >> 12) & 0x3F));
dst[2] = char(0x80 + ((codePoint >> 6) & 0x3F));
dst[3] = char(0x80 + (codePoint & 0x3F));
return 4;
}
}
inline int encodeUnicodePointToUTF16(Char32 codePoint, Char16* outBuffer)
{
Char16* const dst = outBuffer;
if (codePoint <= 0xD7FF || (codePoint >= 0xE000 && codePoint <= 0xFFFF))
{
dst[0] = Char16(codePoint);
return 1;
}
else
{
const uint32_t sub = codePoint - 0x10000;
dst[0] = Char16((sub >> 10) + 0xD800);
dst[1] = Char16((sub & 0x3FF) + 0xDC00);
return 2;
}
}
SLANG_FORCE_INLINE Char16 reverseByteOrder(Char16 val)
{
return (val >> 8) | (val << 8);
}
inline int encodeUnicodePointToUTF16Reversed(Char32 codePoint, Char16* outBuffer)
{
Char16* const dst = outBuffer;
if (codePoint <= 0xD7FF || (codePoint >= 0xE000 && codePoint <= 0xFFFF))
{
dst[0] = reverseByteOrder(Char16(codePoint));
return 1;
}
else
{
const uint32_t sub = codePoint - 0x10000;
const uint32_t high = (sub >> 10) + 0xD800;
const uint32_t low = (sub & 0x3FF) + 0xDC00;
dst[0] = reverseByteOrder(Char16(high));
dst[1] = reverseByteOrder(Char16(low));
return 2;
}
}
static const Char16 kUTF16Header = 0xFEFF;
static const Char16 kUTF16ReversedHeader = 0xFFFE;
class CharEncoding
{
public:
static CharEncoding *UTF8, *UTF16, *UTF16Reversed, *UTF32;
/// Encode Utf8 held in slice append into ioBuffer
virtual void encode(const UnownedStringSlice& str, List<Byte>& ioBuffer) = 0;
/// Decode buffer into Utf8 held in ioBuffer
virtual void decode(const Byte* buffer, int length, List<char>& ioBuffer) = 0;
virtual ~CharEncoding() {}
/// Get the encoding type
CharEncodeType getEncodingType() const { return m_encodingType; }
/// Given some bytes determines a character encoding type, based on the initial bytes.
/// If can't be determined will assume UTF8.
/// Outputs the offset to the first non mark in outOffset
static CharEncodeType determineEncoding(
const Byte* bytes,
size_t bytesCount,
size_t& outOffset);
/// Get the
static CharEncoding* getEncoding(CharEncodeType type) { return g_encoding[Index(type)]; }
CharEncoding(CharEncodeType encodingType)
: m_encodingType(encodingType)
{
}
protected:
CharEncodeType m_encodingType;
static CharEncoding* const g_encoding[Index(CharEncodeType::CountOf)];
};
struct UTF8Util
{
/// Given a slice calculate the number of code points (unicode chars)
///
/// NOTE! This doesn't check the *validity* of code points/encoding.
/// Non valid utf8 input or ending starting in partial characters, will produce
/// undefined results without error.
static Index calcCodePointCount(const UnownedStringSlice& in);
/// Given a slice in UTF8, calculate the number of UTF16 characters needed to represent the
/// string.
static Index calcUTF16CharCount(const UnownedStringSlice& in);
};
} // namespace Slang
#endif
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