marCsweep/gc_alloc.c

#include <stdio.h>
#include <unistd.h>

#include "gc_alloc.h"

static void *allocHead = NULL;

struct gcHeader *findFree(struct gcHeader **prev, size_t size) {
  struct gcHeader *curr = allocHead;

  while (curr && !(curr->free && curr->size >= size)) {
    *prev = curr;
    curr = curr->next;
  }

  return curr;
}

struct gcHeader *requestMem(struct gcHeader *prev, size_t size) {
  struct gcHeader *block;
  void *request;

  block = sbrk(0);
  if (block == (void *)-1) {
    perror("sbrk block");
    return NULL;
  }

  request = sbrk(size + sizeof(struct gcHeader));
  if (request == (void *)-1) {
    perror("sbrk request");
    return NULL;
  }

  if ((void *)block != request) {
    fprintf(stderr, "gcHeader: block != request");
    return NULL;
  }

  if (prev) {
    prev->next = block;
  }

  block->size = size;
  block->next = NULL;
  block->free = 0;

  return block;
}