src/ResText/codecvt.cpp

   1 #include "codecvt.h"
   2
   3 using namespace std;
   4
   5 ucs2_conversion::result
   6 ucs2_conversion::do_in(mbstate_t&,
   7                                            const char*  from, const char* from_end, const char*& from_next,
   8                                            wchar_t* to, wchar_t* to_limit, wchar_t*& to_next) const
   9 {
  10         size_t max_input = (from_end - from) & ~1;
  11         size_t max_output = (to_limit - to);
  12         size_t count = min(max_input/2, max_output);
  13
  14         result res = ok;
  15
  16         from_next = from;
  17         to_next = to;
  18         for (;count--; from_next += 2, ++to_next) {
  19                 unsigned char c1 = *from_next, c2 = *(from_next + 1);
  20                 *to_next = c1 | c2 << 8;
  21         }
  22         if (to_next == to && from_next == from_end - 1) res = partial;
  23         return res;
  24 }
  25
  26 ucs2_conversion::result
  27 ucs2_conversion::do_out(mbstate_t&,
  28                                   const wchar_t* from, const wchar_t* from_end, const wchar_t*& from_next,
  29                                   char* to, char* to_limit, char*& to_next) const
  30 {
  31         size_t max_input = (from_end - from);
  32         size_t max_output = (to_limit - to) & ~1;
  33         size_t count = min(max_input, max_output/2);
  34
  35         from_next = from;
  36         to_next = to;
  37         for (;count--; ++from_next, to_next += 2) {
  38                 *(to_next + 0) = (char)(*from_next & 0xFF);
  39                 *(to_next + 1) = (char)(*from_next >> 8 & 0xFF);
  40         }
  41         return ok;
  42 }
  43
  44 typedef unsigned char uchar;
  45
  46 inline unsigned char
  47 take_6_bits(unsigned value, size_t right_position)
  48 {
  49         return uchar((value >> right_position) & 63);
  50 }
  51
  52
  53
  54 inline size_t
  55 most_signifant_bit_position(unsigned value)
  56 {
  57         size_t result(0);
  58
  59         size_t half = 16;
  60         for(; half > 0; half >>= 1) {
  61                 if (1u << (result + half) <= value ) result += half;
  62         }
  63         return result + 1;
  64         //return *lower_bound(range(0u, 31u), \x -> (1 << x <= value));
  65 }
  66
  67
  68
  69 utf8_conversion::result
  70 utf8_conversion::do_in(mbstate_t&,
  71                                            const char*  from, const char* from_end, const char*& from_next,
  72                                            wchar_t* to, wchar_t* to_limit, wchar_t*& to_next) const
  73 {
  74         from_next = from;
  75         to_next = to;
  76
  77         for(; to_next < to_limit && from_next < from_end; ++to_next) {
  78
  79                 if (uchar(*from_next) < 0x80) *to_next = uchar(*from_next++);
  80                 else {
  81
  82                         // 111zxxxx : z = 0 xxxx are data bits
  83                         size_t zero_bit_pos = most_signifant_bit_position(~*from_next);
  84                         size_t extra_bytes  = 7 - zero_bit_pos;
  85
  86                         if (size_t(from_end - from_next) < extra_bytes + 1)
  87                                 return partial;
  88
  89                         *to_next = uchar(*from_next++) & (wchar_t)((1 << (zero_bit_pos - 1)) - 1);
  90
  91                         for (;extra_bytes--; ++from_next) {
  92                                 *to_next = *to_next << 6  |  uchar(*from_next) & 63;
  93                         }
  94                 }
  95         }
  96
  97         return ok;
  98 }
  99
 100
 101 utf8_conversion::result
 102 utf8_conversion::do_out(mbstate_t&,
 103                                   const wchar_t* from, const wchar_t* from_end, const wchar_t*& from_next,
 104                                   char* to, char* to_limit, char*& to_next) const
 105 {
 106                 from_next = from;
 107                 to_next = to;
 108
 109                 for (;from_next < from_end; ++from_next) {
 110
 111                         unsigned symbol = *from_next;
 112
 113                         if (symbol < 0x7F) {
 114                                 if (to_next < to_limit)
 115                                         *to_next++ = (unsigned char)symbol;
 116                                 else
 117                                         return ok;
 118                         } else {
 119
 120                                 size_t msb_pos = most_signifant_bit_position(symbol);
 121                                 size_t extra_bytes = msb_pos / 6;
 122
 123                                 if (size_t(to_limit - to_next) >= extra_bytes + 1) {
 124
 125                                         *to_next = uchar(0xFF80 >> extra_bytes);
 126                                         *to_next++ |= take_6_bits(symbol, extra_bytes*6);
 127
 128                                         for(;extra_bytes--;)
 129                                                 *to_next++ = 0x80 | take_6_bits(symbol, extra_bytes*6);
 130                                 }
 131                                 else
 132                                         return ok;
 133                         }
 134                 }
 135                 return ok;
 136 }
 137