a// =================================================================================================================

// xs_UTF16Decode

// =================================================================================================================

int32 xs_UTF16Decode (uint32 &code, const xs_utf16* str, int32 len, bool strict)

{

if (str==0||len==0) {code=0; return 0;}

uint32 c1 = str[0];

//note: many implementations test from HighStart to HighEnd,

// this may be a partial code point, and is incorrect(?)

// trivial checking should exclude the WHOLE surrogate range

if (c1<xs_UTF16_HighStart || c1>xs_UTF16_LowEnd) return 1;

//really an error if we're starting in the low range

//surrogate pair

if (len<=1 || str[1]==0) {code=xs_UTF_Replace; return strict ? 0 : 1;} //error

uint32 c2 = str[1];

code = ((c1-xs_UTF16_HighStart)<<xs_UTF16_HalfShift) + (c2-xs_UTF16_LowStart) + xs_UTF16_HalfBase;

if (strict==false) return 2;

//check for errors

if (c1>=xs_UTF16_LowStart && c1<=xs_UTF16_LowEnd) {code=xs_UTF_Replace; return 0;} //error

if (c2<xs_UTF16_LowStart || c2>xs_UTF16_LowEnd) {code=xs_UTF_Replace; return 0;} //error

if (code>xs_UTF_Max) {code=xs_UTF_Replace; return 0;} //error

//success

return 2;

}