1: /*	bitmap.c	1.9	83/05/13	*/
   2: 
   3: #include <stdio.h>
   4: #include "cpmio.h"
   5: int bm_size;
   6: 
   7: /*
   8:  * Bit map handling routines;
   9:  * - build the disk allocation bit map
  10:  * - allocate a new block
  11:  * - dump the bitmap in hex to stdout (debugging)
  12:  * - count the number of blocks in use
  13:  * Note: the first block is number zero and the
  14:  * 	 directory always occupies the first few blocks,
  15:  * 	 depending on the disk format. For a standard
  16:  * 	 SSSD disk the blocks are numbered 0 thru 243 and
  17:  * 	 the directory occupies blocks 0 and 1.
  18:  */
  19: 
  20: /*
  21:  * Allocate a new disk block, return NULL if disk full
  22:  */
  23: char
  24: alloc()
  25: 
  26: {
  27: 
  28:     int i, j, blk;
  29: 
  30:     for (i=0; i<bm_size; i++) {
  31:         j = ffc(0, INTSIZE, *(bitmap+i));
  32:         if ( j < INTSIZE) break;
  33:     }
  34:     blk = i * INTSIZE + j;
  35:     if (blk >= (seclth*sectrk*(tracks-2))/blksiz)
  36:         return ('\0');
  37:     *(bitmap+i) |= (1 << j); /* set the appropriate bit in the bitmap */
  38: #ifdef DEBUG
  39:     printf("block number allocated: %d (0x%x)\n", blk, blk);
  40:     dbmap("new bitmap:");
  41: #endif
  42:     return ((char) blk);
  43: }
  44: 
  45: 
  46: /*
  47:  * Dump the bitmap in hex to stdout, used only for debugging
  48:  */
  49: 
  50: dbmap(str)
  51:     char *str;
  52: {
  53: #ifdef DEBUG
  54: 
  55:     int i;
  56: 
  57:     printf("%s\n",str);
  58:     for (i=0; i<bm_size; i++)
  59:         printf("%.8x\n", *(bitmap+i));
  60: #endif
  61: }
  62: 
  63: /*
  64:  * Return the number of bloks used in the
  65:  * directory, including the directory blocks
  66:  */
  67: 
  68: blks_used()
  69: {
  70: 
  71:     int j, i, temp;
  72:     int buse = 0;
  73: 
  74:     for (i=0; i < bm_size; i++) {
  75:         if (*(bitmap+i) == 0)
  76:             continue;
  77:         if (*(bitmap+i) == -1) {
  78:             buse += INTSIZE;
  79:         } else  {
  80:             temp = *(bitmap+i);
  81:             for (j=0; j < INTSIZE; j++) {
  82:                 if (1 & temp)
  83:                     ++buse;
  84:                 temp >>= 1;
  85:             }
  86:         }
  87:     }
  88:     return (buse);
  89: }
  90: 
  91: 
  92: build_bmap()
  93: {
  94: 
  95:     int i, j, *malloc(), offset, block;
  96: 
  97:     bm_size = 1 + ((seclth*sectrk*(tracks-2))/blksiz)/INTSIZE;
  98: 
  99:     if (!bitmap) {
 100:         if ((bitmap = malloc(bm_size*4)) == NULL) {
 101:             printf("can't allocate memory for bitmap\n");
 102:             exit(1);
 103:         }
 104:     }
 105:     /*
 106: 	 * clear bitmap
 107: 	 */
 108:     for (i=0; i<bm_size; i++)
 109:         bitmap[i] = 0;
 110: 
 111:     /* i equals the number of blocks occupied by the directory */
 112:     i = (maxdir*32)/blksiz;
 113: 
 114:     /* set the directory blocks busy in the bitmap */
 115:     *bitmap = (1 << i) -1;
 116:     for (i=0; i<maxdir; i++) {
 117:         if ((dirbuf+i)->status != (char) 0xe5)  {
 118: #ifdef DEBUG
 119:               printf("%d ->%8s\n", i, (dirbuf+i)->name);
 120: #endif
 121:               for (j=0; (j<16)&&((dirbuf+i)->pointers[j] != '\0'); j++){
 122:                block = 0xff & (int)(dirbuf+i)->pointers[j];
 123:                offset = block / INTSIZE;
 124: #ifdef DEBUG
 125:         printf("blk:%d, offs:%d, bit:%d\n", block,offset,block%INTSIZE);
 126: #endif
 127:               *(bitmap+offset) |= (1 << block % INTSIZE);
 128:               }
 129:         }
 130:     }
 131: #ifdef DEBUG
 132:     dbmap("initial bit map:");
 133: #endif
 134: }

Defined functions

alloc defined in line 23; used 4 times
blks_used defined in line 68; used 1 times
build_bmap defined in line 92; used 2 times
dbmap defined in line 50; used 3 times

Defined variables

bm_size defined in line 5; used 6 times
Last modified: 1983-06-24
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