Cleaning up.

This commit is contained in:
Elf M. Sternberg 2016-12-30 10:53:24 -08:00
parent 1b7c81e469
commit 1bfe867634
1 changed files with 0 additions and 238 deletions

View File

@ -1,238 +0,0 @@
#include <stdio.h>
#include <stdlib.h>
#define MAX_STACK 256
#define MAX_BARRIER 8
typedef enum {
OBJ_INT,
OBJ_PAIR
} ObjectType;
typedef struct sObject {
unsigned char marked;
struct sObject* next;
ObjectType type;
union {
int value;
struct {
struct sObject* head;
struct sObject* tail;
};
};
} Object;
typedef struct {
Object* stack[MAX_STACK];
Object* root;
int stackSize;
int numObjects;
int maxObjects;
} VM;
void assert(int condition, const char* message) {
if (!condition) {
printf("%s\n", message);
exit(1);
}
}
VM* newVM() {
VM* vm = malloc(sizeof(VM));
vm->stackSize = 0;
vm->numObjects = 0;
vm->maxObjects = MAX_BARRIER;
return vm;
}
void push(VM* vm, Object* value) {
assert(vm->stackSize < MAX_STACK, "Stack overflow!");
vm->stack[vm->stackSize++] = value;
}
Object* pop(VM* vm) {
assert(vm->stackSize > 0, "Stack underflow!");
return vm->stack[--(vm->stackSize)];
}
void mark(Object* object) {
if (object->marked) {
return;
}
object->marked = 1;
if (object->type == OBJ_PAIR) {
mark(object->head);
mark(object->tail);
}
}
void markAll(VM* vm) {
for(int i = 0; i < vm->stackSize; i++) {
mark(vm->stack[i]);
}
}
void sweep(VM* vm) {
Object** object = &vm->root;
while (*object) {
if (!(*object)->marked) {
Object* unreached = *object;
*object = unreached->next;
vm->numObjects--;
free(unreached);
} else {
(*object)->marked = 0;
object = &(*object)->next;
}
}
}
void gc(VM* vm) {
int numObjects = vm->numObjects;
markAll(vm);
sweep(vm);
vm->maxObjects = vm->numObjects * 2;
printf("Collected %d objects, %d remaining.\n", numObjects - vm->numObjects,
vm->numObjects);
}
Object *newObject(VM* vm, ObjectType type) {
if (vm->numObjects == vm->maxObjects) {
gc(vm);
}
Object* object = malloc(sizeof(Object));
object->marked = 0;
object->type = type;
object->next = vm->root;
vm->root = object;
vm->numObjects++;
return object;
}
Object* pushInt(VM* vm, int value) {
Object* object = newObject(vm, OBJ_INT);
object->value = value;
push(vm, object);
return object;
}
Object* pushPair(VM* vm) {
Object* object = newObject(vm, OBJ_PAIR);
object->head = pop(vm);
object->tail = pop(vm);
push(vm, object);
return object;
}
void freeVM(VM *vm) {
vm->stackSize = 0;
gc(vm);
free(vm);
}
void objectPrint(Object* object) {
switch(object->type) {
case OBJ_INT:
printf("%d\n", object->value);
break;
case OBJ_PAIR:
printf("(");
objectPrint(object->head);
printf(", ");
objectPrint(object->tail);
printf(")");
break;
}
}
void test1() {
printf("Test 1: Objects on stack are preserved.\n");
VM* vm = newVM();
pushInt(vm, 1);
pushInt(vm, 2);
gc(vm);
assert(vm->numObjects == 2, "Should have preserved objects.");
freeVM(vm);
}
void test2() {
printf("Test 2: Unreached objects are collected.\n");
VM* vm = newVM();
pushInt(vm, 1);
pushInt(vm, 2);
pop(vm);
pop(vm);
gc(vm);
assert(vm->numObjects == 0, "Should have collected objects.");
freeVM(vm);
}
void test3() {
printf("Test 3: Reach nested objects.\n");
VM* vm = newVM();
pushInt(vm, 1);
pushInt(vm, 2);
pushPair(vm);
pushInt(vm, 3);
pushInt(vm, 4);
pushPair(vm);
pushPair(vm);
gc(vm);
assert(vm->numObjects == 7, "Should have reached objects.");
freeVM(vm);
}
void test4() {
printf("Test 4: Handle cycles.\n");
VM* vm = newVM();
pushInt(vm, 1);
pushInt(vm, 2);
Object* a = pushPair(vm);
pushInt(vm, 3);
pushInt(vm, 4);
Object* b = pushPair(vm);
/* Set up a cycle, and also make 2 and 4 unreachable and collectible. */
a->tail = b;
b->tail = a;
gc(vm);
assert(vm->numObjects == 4, "Should have collected objects.");
freeVM(vm);
}
void perfTest() {
printf("Performance Test.\n");
VM* vm = newVM();
for (int i = 0; i < 1000; i++) {
for (int j = 0; j < 20; j++) {
pushInt(vm, i);
}
for (int k = 0; k < 20; k++) {
pop(vm);
}
}
freeVM(vm);
}
int main(int argc, const char * argv[]) {
test1();
test2();
test3();
test4();
perfTest();
return 0;
}