mirror of
https://github.com/jezhiggins/arabica
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91 lines
2.6 KiB
C++
91 lines
2.6 KiB
C++
//---------------------------------------------------------------------------
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// $Id$
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//---------------------------------------------------------------------------
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#include "utf16_utf8.h"
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//---------------------------------------------------------------------------
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// Some of this code is derived from work done by Ken Thompson,
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// provided to the X/Open Group.
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//
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// I got my information about UTF-8 from RFC 2044.
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namespace {
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struct Tab
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{
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char char_mask;
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char char_value;
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int shift;
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wchar_t wide_mask;
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};
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static const Tab tab[] =
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{
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{ char(0x80), char(0x00), 0*6, 0x7F, }, // 1 byte sequence
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{ char(0xE0), char(0xC0), 1*6, 0x7FF, }, // 2 byte sequence
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{ char(0xF0), char(0xE0), 2*6, 0xFFFF, }, // 3 byte sequence
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{ 0, 0, 0, 0, } // end of table
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};
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} // namespace
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std::codecvt_base::result ArabicaInternal::utf16_2_utf8(
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const wchar_t* from, const wchar_t* from_end, const wchar_t*& from_next,
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char* to, char* to_limit, char*& to_next)
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{
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from_next = from;
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to_next = to;
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while(from_next < from_end)
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{
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for(const Tab *t = tab; t->char_mask; t++)
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{
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if(*from_next > t->wide_mask )
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continue;
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// is there enough room in outbuffer?
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if(to_next + (t - tab) + 1 >= to_limit)
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return std::codecvt_base::partial;
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int c = t->shift;
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*to_next++ = static_cast<char>(t->char_value | (*from_next >> c));
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while(c > 0)
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{
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c -= 6;
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*to_next++ = static_cast<char>(0x80 | ((*from_next >> c) & 0x3F));
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} // while(c > 0)
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break;
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} // for(Tab *t = tab; t->char_mask; t++)
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++from_next;
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} // while(from_next < from_end)
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return std::codecvt_base::ok;
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} // iso88591_2_utf8
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std::codecvt_base::result ArabicaInternal::utf8_2_utf16(
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const char* from, const char* from_end, const char*& from_next,
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wchar_t* to, wchar_t* to_limit, wchar_t*& to_next)
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{
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from_next = from;
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to_next = to;
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while((from_next < from_end) && (to_next < to_limit))
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{
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char start = *from_next;
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*to_next = static_cast<unsigned char>(*from_next);
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for(const Tab *t = tab; t->char_mask; t++)
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{
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if((start & t->char_mask) == t->char_value)
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{
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*to_next &= t->wide_mask;
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break;
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}
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from_next++;
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*to_next = (*to_next << 6) | ((*from_next ^ 0x80) & 0xff);
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} // for(Tab *t = tab; t->char_mask; t++)
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++from_next;
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++to_next;
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} // while
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return (from_next == from_end) ? std::codecvt_base::ok : std::codecvt_base::partial;
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} // utf8_2_iso88591
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// end of file
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