UNIX 6th Ed. - /usr/sys/ken/malloc.c

   1: #
   2: /*
   3:  */
   4: 
   5: /*
   6:  * Structure of the coremap and swapmap
   7:  * arrays. Consists of non-zero count
   8:  * and base address of that many
   9:  * contiguous units.
  10:  * (The coremap unit is 64 bytes,
  11:  * the swapmap unit is 512 bytes)
  12:  * The addresses are increasing and
  13:  * the list is terminated with the
  14:  * first zero count.
  15:  */
  16: struct map
  17: {
  18:     char *m_size;
  19:     char *m_addr;
  20: };
  21: 
  22: /*
  23:  * Allocate size units from the given
  24:  * map. Return the base of the allocated
  25:  * space.
  26:  * Algorithm is first fit.
  27:  */
  28: malloc(mp, size)
  29: struct map *mp;
  30: {
  31:     register int a;
  32:     register struct map *bp;
  33: 
  34:     for (bp = mp; bp->m_size; bp++) {
  35:         if (bp->m_size >= size) {
  36:             a = bp->m_addr;
  37:             bp->m_addr =+ size;
  38:             if ((bp->m_size =- size) == 0)
  39:                 do {
  40:                     bp++;
  41:                     (bp-1)->m_addr = bp->m_addr;
  42:                 } while ((bp-1)->m_size = bp->m_size);
  43:             return(a);
  44:         }
  45:     }
  46:     return(0);
  47: }
  48: 
  49: /*
  50:  * Free the previously allocated space aa
  51:  * of size units into the specified map.
  52:  * Sort aa into map and combine on
  53:  * one or both ends if possible.
  54:  */
  55: mfree(mp, size, aa)
  56: struct map *mp;
  57: {
  58:     register struct map *bp;
  59:     register int t;
  60:     register int a;
  61: 
  62:     a = aa;
  63:     for (bp = mp; bp->m_addr<=a && bp->m_size!=0; bp++);
  64:     if (bp>mp && (bp-1)->m_addr+(bp-1)->m_size == a) {
  65:         (bp-1)->m_size =+ size;
  66:         if (a+size == bp->m_addr) {
  67:             (bp-1)->m_size =+ bp->m_size;
  68:             while (bp->m_size) {
  69:                 bp++;
  70:                 (bp-1)->m_addr = bp->m_addr;
  71:                 (bp-1)->m_size = bp->m_size;
  72:             }
  73:         }
  74:     } else {
  75:         if (a+size == bp->m_addr && bp->m_size) {
  76:             bp->m_addr =- size;
  77:             bp->m_size =+ size;
  78:         } else if (size) do {
  79:             t = bp->m_addr;
  80:             bp->m_addr = a;
  81:             a = t;
  82:             t = bp->m_size;
  83:             bp->m_size = size;
  84:             bp++;
  85:         } while (size = t);
  86:     }
  87: }

Defined functions

Defined struct's