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107 lines
3.1 KiB
107 lines
3.1 KiB
#include "src/memory.h"
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#include "src/panic.h"
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#include "src/util.h"
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#include <stdint.h>
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#define MEMORY_SIZE 134217728
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#define PAGE_SIZE 4096
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#define PAGE_COUNT (MEMORY_SIZE / PAGE_SIZE)
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#define MAP_UNIT 64
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#define FULL_UNIT 0xFFFFFFFFFFFFFFFF
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// Claim 2MB for bootloader, kernel, and stuff.
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static uint16_t free_page = MAP_UNIT * 8;
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static uint64_t allocation[PAGE_COUNT / MAP_UNIT] = {FULL_UNIT, FULL_UNIT, FULL_UNIT, FULL_UNIT,
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FULL_UNIT, FULL_UNIT, FULL_UNIT, FULL_UNIT};
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static uint8_t get_allocated(uint16_t page) {
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return !!allocation[page / MAP_UNIT] & ((uint64_t)1 << (page % MAP_UNIT));
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}
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static void set_allocated(uint16_t page, uint8_t allocated) {
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if (allocated) {
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allocation[page / MAP_UNIT] |= ((uint64_t)1 << (page % MAP_UNIT));
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} else {
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allocation[page / MAP_UNIT] &= ~((uint64_t)1 << (page % MAP_UNIT));
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}
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}
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static void *memory_page_allocate() {
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ASSERT(free_page < PAGE_COUNT, "memory_page_allocate: out of memory");
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const uint16_t page = free_page;
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set_allocated(page, 1);
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for (uint16_t unit = free_page / MAP_UNIT; unit < PAGE_COUNT / MAP_UNIT; unit++) {
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if (allocation[unit] != FULL_UNIT) {
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uint16_t bit = (uint16_t)__builtin_ctzll(~allocation[unit]);
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free_page = unit * MAP_UNIT + bit;
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break;
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}
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}
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return (void *)((uint64_t)page * PAGE_SIZE);
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}
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__attribute__((unused)) static void memory_page_free(void *address) {
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uint16_t page = (uint16_t)((uint64_t)address / PAGE_SIZE);
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ASSERT(get_allocated(page), "memory_page_free: page not allocated")
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set_allocated(page, 0);
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if (page < free_page) {
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free_page = page;
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}
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}
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#define HEAP_PAGE_COUNT 256
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typedef struct free_chunk {
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uint64_t size; // header + data
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struct free_chunk *next;
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} free_chunk_t;
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static free_chunk_t *free_list;
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void memory_init() {
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free_list = memory_page_allocate();
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for (uint64_t i = 1; i < HEAP_PAGE_COUNT; i++) {
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memory_page_allocate(); // TODO Map the pages.
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}
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free_list->size = HEAP_PAGE_COUNT * PAGE_SIZE;
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free_list->next = NUL;
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}
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void *memory_allocate(uint64_t size) {
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size = sizeof(free_chunk_t) + (size + 7) & (uint64_t)~7;
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free_chunk_t *prev = NUL;
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free_chunk_t *curr = free_list;
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while (curr) {
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if (curr->size >= size + (sizeof(free_chunk_t) + 8)) {
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free_chunk_t *remainder = (free_chunk_t *)((uint8_t *)curr + size);
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remainder->size = curr->size - size;
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remainder->next = curr->next;
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curr->size = size;
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curr->next = remainder;
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}
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if (curr->size >= size) {
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if (prev) {
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prev->next = curr->next;
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} else {
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free_list = curr->next;
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}
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void *result = (void *)((uint8_t *)curr + sizeof(free_chunk_t));
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memory_set(0, size - sizeof(free_chunk_t), result);
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return result;
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}
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prev = curr;
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curr = curr->next;
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}
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ASSERT(0, "memory_heap_allocate: out of heap memory");
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return 0;
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}
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void memory_free(void *pointer) {
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free_chunk_t *chunk = (free_chunk_t *)((uint8_t *)pointer - sizeof(free_chunk_t));
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chunk->next = free_list;
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free_list = chunk;
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// TODO Merge adjacent free chunks.
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}
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