75 lines
1.9 KiB
C++
75 lines
1.9 KiB
C++
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#include "list.hpp"
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#include <cstdio>
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// pop the last block
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block* list_unlink (list* l) {
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// we need a list
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if (!l) return nullptr;
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block* b = l->end;
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// can't unlink from an empty list
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if (!b) return nullptr;
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// remove b
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if (b->prev) {
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// b is not the only element of the list
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// chop of the tail
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l->end = b->prev;
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// bandage the wound
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l->end->next = nullptr;
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// wrap the severed end
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b->prev = nullptr;
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} else {
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// b is the only element of the list
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l->start = nullptr;
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l->end = nullptr;
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}
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// if we get here, we've removed element b from the list
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l->length--;
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return b;
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}
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// push a block
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void list_link (list* l, block* b) {
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// can't link to a nonexistent list
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if (!l) return;
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// can't append nullptr;
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if (!b) return;
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if (l->start == nullptr) {
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// b is the only element of the list
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l->start = b;
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l->end = b;
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} else {
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// make b the next element of the list
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b->prev = l->end;
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l->end->next = b;
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// terminate the list
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b->next = nullptr;
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// update end
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l->end = b;
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}
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l->length++;
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}
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// push a lot of blocks
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// this is slow, but the pointer arithmetic *has* to be done for each block
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// so it's not really as slow as it would be, were that not the case.
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void list_init (list *l, block *m, int size) {
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// move each block of memory into the freelist, by linking it to the end
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for (int b = 0; b < size; b++) {
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list_link(l, &(m[b]));
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}
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}
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// YAML-like, because I like YAML
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void list_print(list *l) {
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if (!l) return;
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std::printf("l_%p:\n - start: '%p',\n - end: '%p',\n - length: '%d',\n - blocks:",l,l->start,l->end,l->length);
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block* b = l->start;
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if (b) {
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do {
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std::printf("\n - b_%p: [prev: '%p', next: '%p', data: '%d']",b,b->prev,b->next,b->data);
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} while (b = b->next);
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std::printf("\n");
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} else {
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std::printf(" []\n");
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}
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}
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