sh.exec.h

Variables

hits              X
misses            X
xhash             X

Macros

HSHMASK           X
HSHMUL            X
HSHSIZ            X
bis               X
bit               X
hash              X

   1: /*
   2:  * Xhash is an array of HSHSIZ bits (HSHSIZ / 8 chars), which are used
   3:  * to hash execs.  If it is allocated (havhash true), then to tell
   4:  * whether ``name'' is (possibly) present in the i'th component
   5:  * of the variable path, you look at the bit in xhash indexed by
   6:  * hash(hashname("name"), i).  This is setup automatically
   7:  * after .login is executed, and recomputed whenever ``path'' is
   8:  * changed.
   9:  * The two part hash function is designed to let texec() call the
  10:  * more expensive hashname() only once and the simple hash() several
  11:  * times (once for each path component checked).
  12:  * Byte size is assumed to be 8.
  13:  */
  14: #define HSHSIZ      8192            /* 1k bytes */
  15: #define HSHMASK     (HSHSIZ - 1)
  16: #define HSHMUL      243
  17: char    xhash[HSHSIZ / 8];
  18: #define hash(a, b)  ((a) * HSHMUL + (b) & HSHMASK)
  19: #define bit(h, b)   ((h)[(b) >> 3] & 1 << ((b) & 7))    /* bit test */
  20: #define bis(h, b)   ((h)[(b) >> 3] |= 1 << ((b) & 7))   /* bit set */
  21: #ifdef VFORK
  22: int hits, misses;
  23: #endif