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diff --git a/support/texlab/crates/bibutils_sys/src/gb18030.c b/support/texlab/crates/bibutils_sys/src/gb18030.c
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+#include <stdio.h>
+#include "gb18030.h"
+
+/* GB18030-2000 is an encoding of Unicode character used in China
+ *
+ * {0x00-0x7f} are one byte characters identical to US-ASCII
+ * {0x80} is properly undefined, but many GB18030 encodings make
+ * it the Euro sign (Unicode 0x20AC), so use that
+ * {0x81-0xFE}{0x40-0x7E,0x80-0xFE} a full superset of GBK (with fallback
+ * mappings)
+ * {0x81-0xFE}{0x30-0x39}{0x81-0xFE}{0x30-0x39} maps linearly to ISO 10646
+ * GB+81308130 = U+0080 up to U+FFFF
+ * GB+90308130 = U+10000 up to U+10FFFF skipping mappings already
+ * defined in 1-byte and 2-byte areas.
+ *
+ * Truth is it's a bit of a mess algorithmically as it doesn't multiply
+ * encode characters, so there are holes in the Unicode mapping that
+ * should be avoided.
+ */
+
+/* This is a "small" region that needs explicit enumeration */
+#include "gb18030_enumeration.c"
+
+static int
+in_range( unsigned char n, unsigned char low, unsigned char high )
+{
+ if ( n < low || n > high ) return 0;
+ return 1;
+}
+
+
+/* Get GB 18030 from Unicode Value in Table */
+static int
+gb18030_unicode_table_lookup( unsigned int unicode, unsigned char out[4] )
+{
+ int i, j;
+ if ( unicode >= 0x0080 && unicode <= 0xFFE5 ) {
+ /* list is sorted, so should do binary search here */
+ for ( i=0; i<ngb18030_enums; ++i ) {
+ if ( unicode == gb18030_enums[i].unicode ) {
+ for ( j=0; j<gb18030_enums[i].len; ++j )
+ out[j] = gb18030_enums[i].bytes[j];
+ return gb18030_enums[i].len;
+ }
+ }
+ }
+ return 0;
+}
+
+static int
+gb18030_match( unsigned char *s, const unsigned char *bytes, unsigned char len )
+{
+ int i;
+ for ( i=0; i<len; ++i )
+ if ( ( s[i])!=bytes[i] ) return 0;
+ return 1;
+}
+
+static unsigned int
+gb18030_table_lookup( unsigned char *uc, unsigned char len, int *found )
+{
+ unsigned int i;
+ *found = 0;
+ for ( i=0; i<ngb18030_enums; ++i ) {
+ if ( gb18030_enums[i].len!=len ) continue;
+ if ( gb18030_match( &(uc[0]), gb18030_enums[i].bytes, len ) ) {
+ *found = 1;
+ return gb18030_enums[i].unicode;
+ }
+ }
+ return '?';
+}
+
+
+static int
+gb18030_unicode_range_lookup( unsigned int unicode, unsigned char out[4] )
+{
+ return 0;
+}
+
+static int
+gb18030_range_lookup( unsigned char *s, /* unsigned char len = 4 only */ int *found )
+{
+ *found = 0;
+ return 0;
+#if 0
+ <!-- Roundtrip-mappings that can be enumerated
+ Note that GB 18030 defines roundtrip mappings for all Unicode code points U+0000..U+10ffff.
+ This would require 1.1 million <a> elements.
+ However, most four-byte GB 18030 mappings can be enumerated efficiently within distinct ranges.
+ Therefore, we use <range> elements for all but the 31000 or so assignments above.
+ -->
+ <range uFirst="0452" uLast="200F" bFirst="81 30 D3 30" bLast="81 36 A5 31" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="2643" uLast="2E80" bFirst="81 37 A8 39" bLast="81 38 FD 38" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="361B" uLast="3917" bFirst="82 30 A6 33" bLast="82 30 F2 37" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="3CE1" uLast="4055" bFirst="82 31 D4 38" bLast="82 32 AF 32" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="4160" uLast="4336" bFirst="82 32 C9 37" bLast="82 32 F8 37" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="44D7" uLast="464B" bFirst="82 33 A3 39" bLast="82 33 C9 31" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="478E" uLast="4946" bFirst="82 33 E8 38" bLast="82 34 96 38" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="49B8" uLast="4C76" bFirst="82 34 A1 31" bLast="82 34 E7 33" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="9FA6" uLast="D7FF" bFirst="82 35 8F 33" bLast="83 36 C7 38" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="E865" uLast="F92B" bFirst="83 36 D0 30" bLast="84 30 85 34" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="FA2A" uLast="FE2F" bFirst="84 30 9C 38" bLast="84 31 85 37" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="FFE6" uLast="FFFF" bFirst="84 31 A2 34" bLast="84 31 A4 39" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+ <range uFirst="10000" uLast="10FFFF" bFirst="90 30 81 30" bLast="E3 32 9A 35" bMin="81 30 81 30" bMax="FE 39 FE 39"/>
+#endif
+}
+
+unsigned int
+gb18030_to_unicode( unsigned char *s, unsigned char len )
+{
+ unsigned int ret;
+ int found;
+ ret = gb18030_table_lookup( s, len, &found );
+ if ( !found && len==4 ) {
+ ret = gb18030_range_lookup( s, &found );
+ if ( !found ) ret = '?';
+ }
+ return ret;
+}
+
+/*
+ * Convert unicode character to gb18030
+ *
+ * returns number of characters for output
+ */
+int
+gb18030_encode( unsigned int unicode, unsigned char out[4] )
+{
+ int len;
+ if ( unicode < 0x80 ) {
+ out[0] = unicode;
+ len = 1;
+ } else {
+ len = gb18030_unicode_table_lookup( unicode, out );
+ if ( !len )
+ len = gb18030_unicode_range_lookup( unicode, out );
+ }
+ return len;
+}
+
+/*
+ * Decode a gb18030 character into unicode
+ */
+unsigned int
+gb18030_decode( char *s, unsigned int *pi )
+{
+ unsigned int c;
+ unsigned char uc[4];
+ int i = *pi;
+ uc[0] = ( unsigned char ) s[i];
+ if ( ( uc[0] & 128 ) == 0 ) {
+ c = ( unsigned int ) uc[0];
+ i += 1;
+ } else if ( uc[0] == 0x80 ) {
+ c = 0x20AC;
+ i += 1;
+ } else if ( uc[0] != 0xFF ) { /* multi-byte character */
+ uc[1] = ( unsigned char ) s[i+1];
+ uc[2] = ( unsigned char ) s[i+2];
+ uc[3]= ( unsigned char ) s[i+3];
+ if ( in_range( uc[1], 0x40, 0x7e ) || in_range( uc[1], 0x80, 0xfe ) ) {
+ /* two-byte character */
+ c = gb18030_to_unicode( &(uc[0]), 2 );
+ i += 2;
+ } else if ( in_range( uc[1], 0x30, 0x39 ) &&
+ in_range( uc[2], 0x81, 0xfe ) &&
+ in_range( uc[3], 0x30, 0x39 ) ) {
+ /* four-byte character */
+ c = gb18030_to_unicode( &(uc[0]), 4 );
+ i += 4;
+ } else {
+ /* this is an illegal character */
+ c = '?';
+ i += 1;
+ }
+ } else { /* s[i]==0xFF */
+ /* this is an illegal character */
+ c = '?';
+ i += 1;
+ }
+ *pi = i;
+ return c;
+}