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/* mem.c -- fast memory allocation/deallocation module */
/* Allocate large chunks of memory using malloc. From the chunks,
allocate memory as needed on long-word boundaries. Memory is
freed by linking memory onto a freelist. An array of freelists,
one for each size, is maintained and checked before going to the
chunck for more memory. The freelist array only holds lists of
nodes up to a certain size. After that, malloc is used directly.
*/
/* CHANGE LOG
----------------------------------------------------------------------
10-Oct-20 | RBD : change to 8-byte alignment
28-Apr-03 | DM : fix #includes for portability
----------------------------------------------------------------------
*/
#include "switches.h"
#include <stdio.h>
#include <stdlib.h>
#include "cext.h"
#include "userio.h"
/* how many bytes in the largest node managed in mem_free_list array */
#define MAX_SIZE_FOR_FREELIST 256
intptr_t *mem_free_list[MAX_SIZE_FOR_FREELIST/8];
#define MEM_CHUNK_SIZE 4096
char *mem_chunk;
intptr_t mem_chunk_remaining = 0;
void meminit()
{
int i;
for (i = 0; i < MAX_SIZE_FOR_FREELIST/8; i++) {
mem_free_list[i] = NULL;
}
}
void *memget(register size_t size)
{
if (size > MAX_SIZE_FOR_FREELIST) {
/* gprintf(TRANS, "memget calling MALLOC\n"); */
return MALLOC(size);
} else {
/* 8 -> 0, 9 -> 1, 256 -> 31 */
intptr_t **p = mem_free_list + ((size - 1) >> 3);
if (*p) {
intptr_t *result = *p;
*p = (intptr_t *) *result;
/* gprintf(TRANS, "memget->%lx\n", result); */
return (char *) result;
} else if ((size_t) mem_chunk_remaining >= size) {
char *result = mem_chunk;
size = (size + 7) & ~7; /* round up to multiple of 8 */
mem_chunk += size;
mem_chunk_remaining -= size;
/* gprintf(TRANS, "memget->%lx\n", result); */
return result;
/* note that we throw away remaining chunk when there isn't enough */
} else if ((mem_chunk = (char *) MALLOC(MEM_CHUNK_SIZE))) {
register char *result = mem_chunk;
/* gprintf(TRANS, "mem_chunk at %lx\n", mem_chunk); */
size = (size + 7) & ~7; /* round up to multiple of 8 */
mem_chunk += size;
mem_chunk_remaining = MEM_CHUNK_SIZE - size;
/* gprintf(TRANS, "memget->%lx\n", result); */
return result;
} else {
return NULL;
}
}
}
void memfree(register void *ptr, register size_t size)
{
intptr_t **p = (intptr_t **) ptr;
if (size > MAX_SIZE_FOR_FREELIST) {
FREE(ptr);
} else {
intptr_t **head_ptr = mem_free_list + ((size - 1) >> 3);
*p = *head_ptr;
*head_ptr = (intptr_t *) p;
}
}
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