src/locale/__mo_lookup.c

   1 #include <stdint.h>
   2 #include <string.h>
   3
   4 static inline uint32_t swapc(uint32_t x, int c)
   5 {
   6         return c ? x>>24 | x>>8&0xff00 | x<<8&0xff0000 | x<<24 : x;
   7 }
   8
   9 const char *__mo_lookup(const void *p, size_t size, const char *s)
  10 {
  11         const uint32_t *mo = p;
  12         int sw = *mo - 0x950412de;
  13         uint32_t b = 0, n = swapc(mo[2], sw);
  14         uint32_t o = swapc(mo[3], sw);
  15         uint32_t t = swapc(mo[4], sw);
  16         if (n>=size/4 || o>=size-4*n || t>=size-4*n || ((o|t)%4))
  17                 return 0;
  18         o/=4;
  19         t/=4;
  20         for (;;) {
  21                 uint32_t ol = swapc(mo[o+2*(b+n/2)], sw);
  22                 uint32_t os = swapc(mo[o+2*(b+n/2)+1], sw);
  23                 if (os >= size || ol >= size-os || ((char *)p)[os+ol])
  24                         return 0;
  25                 int sign = strcmp(s, (char *)p + os);
  26                 if (!sign) {
  27                         uint32_t tl = swapc(mo[t+2*(b+n/2)], sw);
  28                         uint32_t ts = swapc(mo[t+2*(b+n/2)+1], sw);
  29                         if (ts >= size || tl >= size-ts || ((char *)p)[ts+tl])
  30                                 return 0;
  31                         return (char *)p + ts;
  32                 }
  33                 else if (n == 1) return 0;
  34                 else if (sign < 0)
  35                         n /= 2;
  36                 else {
  37                         b += n/2;
  38                         n -= n/2;
  39                 }
  40         }
  41         return 0;
  42 }