68   heap_size len;         // size in units of "sizeof(heap_node)"  member
88   freelist->len = HEAP_SIZE / sizeof(heap_node);  in init_heap()
92 size_t alloc_size(size_t len) {  in alloc_size()  argument
93   return (len + sizeof(heap_node) - 1) / sizeof(heap_node) + 1;  in alloc_size()
100 void* fallback_malloc(size_t len) {  in fallback_malloc()  argument
102   const size_t nelems = alloc_size(len);  in fallback_malloc()
112     if (p->len > nelems) { //  chunk is larger, shorten, and return the tail  in fallback_malloc()
115       p->len = static_cast<heap_size>(p->len - nelems);  in fallback_malloc()
116       q = p + p->len;  in fallback_malloc()
118       q->len = static_cast<heap_size>(nelems);  in fallback_malloc()
122     if (p->len == nelems) { // exact size match  in fallback_malloc()
135 heap_node* after(struct heap_node* p) { return p + p->len; }  in after()
144   std::printf("Freeing item at %d of size %d\n", offset_from_node(cp), cp->len);  in fallback_free()
158       p->len = static_cast<heap_size>(  in fallback_free()
159           p->len + cp->len); // make the free heap_node larger  in fallback_free()
165       cp->len = static_cast<heap_size>(cp->len + p->len);  in fallback_free()
192       (prev == 0 ? "" : "  "), offset_from_node(p), p->len, p->next_node);  in print_free_list()
193     total_free += p->len;  in print_free_list()