Optimized utf8 decoding

git-svn-id: http://pugixml.googlecode.com/svn/trunk@447 99668b35-9821-0410-8761-19e4c4f06640

1 files changed, 23 insertions, 6 deletions

diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index d404652..bf5253f 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -796,9 +796,7 @@ namespace pugi
 		{

 			const char8_t utf8_byte_mask = 0x3f;

 

-			const char8_t* end = data + size;

-

-			while (data < end)

+			while (size)

 			{

 				char8_t lead = *data;

 

@@ -807,29 +805,48 @@ namespace pugi
 				{

 					result = Traits::low(result, lead);

 					data += 1;

+					size -= 1;

+

+					// process aligned single-byte (ascii) blocks

+					if ((reinterpret_cast<uintptr_t>(data) & 3) == 0)

+					{

+						while (size >= 4 && (*reinterpret_cast<const char32_t*>(data) & 0x80808080) == 0)

+						{

+							result = Traits::low(result, data[0]);

+							result = Traits::low(result, data[1]);

+							result = Traits::low(result, data[2]);

+							result = Traits::low(result, data[3]);

+							data += 4;

+							size -= 4;

+						}

+					}

 				}

 				// 110xxxxx -> U+0080..U+07FF

-				else if ((unsigned)(lead - 0xC0) < 0x20 && (end - data) > 1 && (data[1] & 0xc0) == 0x80)

+				else if ((unsigned)(lead - 0xC0) < 0x20 && size >= 2 && (data[1] & 0xc0) == 0x80)

 				{

 					result = Traits::low(result, ((lead & ~0xC0) << 6) | (data[1] & utf8_byte_mask));

 					data += 2;

+					size -= 2;

 				}

 				// 1110xxxx -> U+0800-U+FFFF

-				else if ((unsigned)(lead - 0xE0) < 0x10 && (end - data) > 2 && (data[1] & 0xc0) == 0x80 && (data[2] & 0xc0) == 0x80)

+				else if ((unsigned)(lead - 0xE0) < 0x10 && size >= 3 && (data[1] & 0xc0) == 0x80 && (data[2] & 0xc0) == 0x80)

 				{

 					result = Traits::low(result, ((lead & ~0xE0) << 12) | ((data[1] & utf8_byte_mask) << 6) | (data[2] & utf8_byte_mask));

 					data += 3;

+					size -= 3;

 				}

 				// 11110xxx -> U+10000..U+10FFFF

-				else if ((unsigned)(lead - 0xF0) < 0x08 && (end - data) > 3 && (data[1] & 0xc0) == 0x80 && (data[2] & 0xc0) == 0x80 && (data[3] & 0xc0) == 0x80)

+				else if ((unsigned)(lead - 0xF0) < 0x08 && size >= 4 && (data[1] & 0xc0) == 0x80 && (data[2] & 0xc0) == 0x80 && (data[3] & 0xc0) == 0x80)

 				{

 					result = Traits::high(result, ((lead & ~0xF0) << 18) | ((data[1] & utf8_byte_mask) << 12) | ((data[2] & utf8_byte_mask) << 6) | (data[3] & utf8_byte_mask));

 					data += 4;

+					size -= 4;

 				}

 				// 10xxxxxx or 11111xxx -> invalid

 				else

 				{

 					data += 1;

+					size -= 1;

 				}

 			}