4.3BSD - /usr/src/new/spms/src/lib/libslist/src/slssort.c

   1: /* $Header$ */
   2: 
   3: /*
   4:  * Author: Peter J. Nicklin
   5:  */
   6: 
   7: /*
   8:  * slssort() sorts list slslist according to comparison function compar().
   9:  * compar() is to be called with two arguments and must return an integer
  10:  * greater than, equal to, or less than 0, depending on the lexicographic
  11:  * relationship between the two arguments. Returns integer YES if
  12:  * successful, otherwise NO if out of memory.
  13:  */
  14: #include "null.h"
  15: #include "slslist.h"
  16: #include "yesno.h"
  17: 
  18: static int (*sscmp)();          /* string compare function */
  19: 
  20: slssort(compar, slslist)
  21:     int (*compar)();        /* compare two strings */
  22:     SLSLIST *slslist;       /* pointer to list head block */
  23: {
  24:     char *malloc();         /* memory allocator */
  25:     int bpi;            /* block pointer array index */
  26:     int comparb();          /* compare 2 list blocks */
  27:     SLSBLK **bp;            /* pointer to block pointer array */
  28:     SLSBLK *curblk;         /* current list block */
  29: 
  30:     if (slslist->nk <= 0)
  31:         return(YES);
  32:     else if ((bp = (SLSBLK **) malloc((unsigned)slslist->nk*sizeof(SLSBLK *)))==NULL)
  33:         {
  34:         warn("out of memory");
  35:         return(NO);
  36:         }
  37:     for (bpi=0, curblk=slslist->head; curblk != NULL; bpi++, curblk=curblk->next)
  38:         bp[bpi] = curblk;
  39: 
  40:     sscmp = compar;
  41:     qsort((char *) bp, slslist->nk, sizeof(SLSBLK *), comparb);
  42: 
  43:     for (bpi=0, curblk=slslist->head=bp[bpi++]; bpi < slslist->nk; bpi++)
  44:         curblk = curblk->next = bp[bpi];
  45:     curblk->next = NULL;
  46:     slslist->tail = curblk;
  47: 
  48:     free((char *) bp);
  49:     return(YES);
  50: }
  51: 
  52: 
  53: 
  54: /*
  55:  * comparb() compares key strings in 2 list blocks. Returns whatever
  56:  * sscmp() returns. sscmp() is a string compare function.
  57:  */
  58: 
  59: static int
  60: comparb(b1, b2)
  61:     SLSBLK **b1;            /* block pointer */
  62:     SLSBLK **b2;            /* block pointer */
  63: {
  64:     return(sscmp((*b1)->key, (*b2)->key));
  65: }

Defined functions