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/*
* esh, the Unix shell with Lisp-like syntax.
* Copyright (C) 1999 Ivan Tkatchev
* This source code is under the GPL.
*/
#include <stdlib.h>
#include <stdio.h>
#include "gc.h"
#include "format.h"
/*
* A simplistic garbage collection mechanism. It requires that the C
* program call gc_free whenever an object should be deleted. As such,
* this cannot really be called garbage collection, though it does serve
* a purpose as a central repository of all allocated memory.
*/
int __gc_alloc = 0;
void* gc_alloc(size_t size, char* where) {
void* ret = malloc(size + sizeof(int));
if (!ret) {
error("esh: could not allocate memory.");
exit(EXIT_FAILURE);
}
((int*)ret)[0] = 1;
__gc_alloc++;
return ret + sizeof(int);
}
inline void gc_inc_ref(void* ptr) {
int* ref = (int*)(ptr - sizeof(int));
if ((*ref) <= 0) {
error("esh: refcount is corrupted in gc_inc_ref.");
exit(EXIT_FAILURE);
}
(*ref)++;
__gc_alloc++;
}
void gc_add_ref(void* ptr, int add) {
int* ref = (int*)(ptr - sizeof(int));
if ((*ref) <= 0) {
error("esh: refcount is corrupted in gc_add_ref");
exit(EXIT_FAILURE);
}
(*ref) += add;
__gc_alloc += add;
if ((*ref) <= 0) {
error("esh: tried to set an invalid ref count.");
exit(EXIT_FAILURE);
}
}
inline int gc_refs(void* ptr) {
int* ref = (int*)(ptr - sizeof(int));
if ((*ref) <= 0) {
error("esh: refcount is corrupted in gc_refs.");
exit(EXIT_FAILURE);
}
return (*ref);
}
inline void gc_free(void* ptr) {
int* ref = (int*)(ptr - sizeof(int));
if ((*ref) <= 0) {
error("esh: refcount is corrupted in gc_free.");
exit(EXIT_FAILURE);
}
(*ref)--;
__gc_alloc--;
if (!(*ref)) {
free(ptr - sizeof(int));
}
}
void gc_diagnostics(void) {
printf("\nAllocated chunks: %d\n", __gc_alloc);
}
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