/*
* h.c -- Handle allocation module
*
* Copyright (c) GoAhead Software Inc., 1995-1999. All Rights Reserved.
* See the file "license.txt" for usage and redistribution license requirements
*/
/******************************** Description *********************************/
/*
* This module provides a simple API to allocate and free handles
* It maintains a dynamic array of pointers. These usually point to
* per-handle structures.
*/
/********************************* Includes ***********************************/
#if UEMF
#include "uemf.h"
#else
#include "basic/basicInternal.h"
#endif
/********************************** Defines ***********************************/
/*
* The handle list stores the length of the list and the number of used
* handles in the first two words. These are hidden from the caller by
* returning a pointer to the third word to the caller
*/
#define H_LEN 0 /* First entry holds length of list */
#define H_USED 1 /* Second entry holds number of used */
#define H_OFFSET 2 /* Offset to real start of list */
#define H_INCR 16 /* Grow handle list in chunks this size */
/*********************************** Code *************************************/
/*
* Allocate a new file handle. On the first call, the caller must set the
* handle map to be a pointer to a null pointer. *map points to the second
* element in the handle array.
*/
int hAlloc(void ***map)
{
int *mp;
int handle, len, memsize, incr;
a_assert(map);
if (*map == NULL) {
incr = H_INCR;
memsize = (incr + H_OFFSET) * sizeof(void**);
if ((mp = (int*) balloc(B_L, memsize)) == NULL) {
return -1;
}
memset(mp, 0, memsize);
mp[H_LEN] = incr;
mp[H_USED] = 0;
*map = (void**) &mp[H_OFFSET];
} else {
mp = &((*(int**)map)[-H_OFFSET]);
}
len = mp[H_LEN];
/*
* Find the first null handle
*/
if (mp[H_USED] < mp[H_LEN]) {
for (handle = 0; handle < len; handle++)
if (mp[handle+H_OFFSET] == 0) {
mp[H_USED]++;
return handle;
}
} else {
handle = len;
}
/*
* No free handle so grow the handle list. Grow list in chunks of H_INCR.
*/
len += H_INCR;
memsize = (len + H_OFFSET) * sizeof(void**);
if ((mp = (int*) brealloc(B_L, (void*) mp, memsize)) == NULL) {
return -1;
}
*map = (void**) &mp[H_OFFSET];
mp[H_LEN] = len;
memset(&mp[H_OFFSET + len - H_INCR], 0, sizeof(int*) * H_INCR);
mp[H_USED]++;
return handle;
}
/******************************************************************************/
/*
* Free a handle. This function returns the value of the largest
* handle in use plus 1, to be saved as a max value.
*/
int hFree(void ***map, int handle)
{
int *mp;
int len;
a_assert(map);
mp = &((*(int**)map)[-H_OFFSET]);
a_assert(mp[H_LEN] >= H_INCR);
a_assert(mp[handle + H_OFFSET]);
a_assert(mp[H_USED]);
mp[handle + H_OFFSET] = 0;
if (--(mp[H_USED]) == 0) {
bfree(B_L, (void*) mp);
*map = NULL;
}
/*
* Find the greatest handle number in use.
*/
if (*map == NULL) {
handle = -1;
} else {
len = mp[H_LEN];
if (mp[H_USED] < mp[H_LEN]) {
for (handle = len - 1; handle >= 0; handle--) {
if (mp[handle + H_OFFSET])
break;
}
} else {
handle = len;
}
}
return handle + 1;
}
/******************************************************************************/
/*
* Allocate an entry in the halloc array.
*/
int hAllocEntry(void ***list, int *max, int size)
{
char_t *cp;
int id;
a_assert(list);
a_assert(max);
if ((id = hAlloc((void***) list)) < 0) {
return -1;
}
if (size > 0) {
if ((cp = balloc(B_L, size)) == NULL) {
hFree(list, id);
return -1;
}
a_assert(cp);
memset(cp, 0, size);
(*list)[id] = (void*) cp;
}
if (id >= *max) {
*max = id + 1;
}
return id;
}
/******************************************************************************/
