unicode: __utf8_to_utf16_handler_4bytes(): fix conversion logic.

1 files changed, 28 insertions, 12 deletions

diff --git a/src/unicode/ntapi_uc_unicode_conversion_from_utf8.c b/src/unicode/ntapi_uc_unicode_conversion_from_utf8.c
index ab66a77..2741503 100644
--- a/src/unicode/ntapi_uc_unicode_conversion_from_utf8.c
+++ b/src/unicode/ntapi_uc_unicode_conversion_from_utf8.c
@@ -135,10 +135,14 @@ static int32_t __fastcall __utf8_to_utf16_handler_4bytes(nt_utf8_callback_args *
 	wchar16_t *		dst_lead;
 	wchar16_t *		dst_trail;
 
-	wchar16_t		u;
+	wchar16_t		wwww;
+	wchar16_t		lead;
+	wchar16_t		trail;
 	unsigned char		ulow;
 	unsigned char		uhigh;
+	unsigned char		yy;
 	unsigned char		yyyy;
+	unsigned char		zzzz;
 
 	dst_lead = dst_trail = (wchar16_t *)args->dst;
 	dst_trail++;
@@ -149,27 +153,39 @@ static int32_t __fastcall __utf8_to_utf16_handler_4bytes(nt_utf8_callback_args *
 	src_low	= src_high = (__two_bytes *)args->src;
 	src_high++;
 
-	/* u */
+	/* uuuuu */
 	ulow	= src_low->low  ^ 0xF0;
 	uhigh	= src_low->high ^ 0x80;
 
 	ulow  <<= 2;
 	uhigh >>= 4;
 
-	u = ulow | uhigh;
+	/* wwww */
+	wwww   = (ulow | uhigh) - 1;
+	wwww <<= 6;
 
 	/* 110110ww wwzzzzyy */
-	*dst_lead  = 0xD800;
-	*dst_lead |= ((u-1) << 6);
-	*dst_lead |= ((src_low->high ^ 0x80) << 2);
-	*dst_lead |= ((src_high->low ^ 0x80) >> 4);
+	yy     = src_high->low ^ 0x80;
+	yy   >>= 4;
+
+	zzzz   = src_low->high;
+	zzzz <<= 4;
+	zzzz >>= 2;
+
+	lead   = 0xD800;
+	lead  |= wwww;
+	lead  |= zzzz;
+	lead  |= yy;
 
 	/* 110111yy  yyxxxxxx */
-	yyyy         = (src_high->low << 4);
-	*dst_trail   = yyyy;
-	*dst_trail <<= 2;
-	*dst_trail  |= (src_high->high ^ 0x80);
-	*dst_trail  |= 0xDC00;
+	yyyy   = src_high->low << 4;
+	trail  = yyyy << 2;
+	trail |= src_high->high ^ 0x80;
+	trail |= 0xDC00;
+
+	/* write */
+	*dst_lead  = lead;
+	*dst_trail = trail;
 
 	/* advance source and destination buffer */
 	args->src += 4;