1  /* Tables for conversion to and from ISO-IR-165.
       2     converting from UCS using gaps.
       3     Copyright (C) 2000-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #ifndef _ISO_IR_165_H
      21  #define _ISO_IR_165_H	1
      22  
      23  #include <gconv.h>
      24  #include <stdint.h>
      25  
      26  struct gap
      27  {
      28    uint16_t start;
      29    uint16_t end;
      30    int32_t idx;
      31  };
      32  
      33  /* Table for ISO-IR-165 (CCITT Chinese) to UCS4 conversion.  */
      34  #define ISOIR165_FROMSIZE	0x2284
      35  extern const uint16_t __isoir165_to_tab[ISOIR165_FROMSIZE];
      36  
      37  
      38  /* XXX If we at some point need an offset value to decode the byte
      39     sequences another parameter can be added.  */
      40  static inline uint32_t
      41  __attribute ((always_inline))
      42  isoir165_to_ucs4 (const unsigned char **s, size_t avail)
      43  {
      44    unsigned char ch = *(*s);
      45    unsigned char ch2;
      46    uint32_t res;
      47  
      48    if (ch <= 0x20 || ch >= 0x7f)
      49      return __UNKNOWN_10646_CHAR;
      50  
      51    if (avail < 2)
      52      return 0;
      53  
      54    ch2 = (*s)[1];
      55    if (ch2 <= 0x20 || ch2 >= 0x7f)
      56      return __UNKNOWN_10646_CHAR;
      57  
      58    res = __isoir165_to_tab[(ch - 0x21) * 94 + (ch2 - 0x21)];
      59    if (res == 0)
      60      return __UNKNOWN_10646_CHAR;
      61  
      62    *s += 2;
      63    return res;
      64  }
      65  
      66  
      67  /* Tables for ISO-IR-165 (CCITT Chinese) from UCS4 conversion.  */
      68  extern const struct gap __isoir165_from_idx[];
      69  extern const char __isoir165_from_tab[];
      70  
      71  static inline size_t
      72  __attribute ((always_inline))
      73  ucs4_to_isoir165 (uint32_t wch, unsigned char *s, size_t avail)
      74  {
      75    unsigned int ch = (unsigned int) wch;
      76    const char *cp;
      77    const struct gap *rp = __isoir165_from_idx;
      78  
      79    if (ch > 0xffe5)
      80      /* This is an illegal character.  */
      81      return __UNKNOWN_10646_CHAR;
      82  
      83    while (ch > rp->end)
      84      ++rp;
      85    if (ch < rp->start)
      86      /* This is an illegal character.  */
      87      return __UNKNOWN_10646_CHAR;
      88  
      89    /* The two bytes following the index given in this record give the
      90       encoding in ISO-IR-165.  Unless the bytes are zero.  */
      91    cp = &__isoir165_from_tab[(ch + rp->idx) * 2];
      92    if (*cp == '\0')
      93      /* This is an illegal character.  */
      94      return __UNKNOWN_10646_CHAR;
      95  
      96    if (avail < 2)
      97      return 0;
      98  
      99    s[0] = cp[0];
     100    s[1] = cp[1];
     101  
     102    return 2;
     103  }
     104  
     105  #endif	/* iso-ir-165.h */