109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
#include "../include/memory.h"
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header_t *head = NULL, *tail = NULL; // 内存块链表
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extern page_directory_t *current_directory;
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extern uint32_t end; // declared in linker.ld
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static uint32_t placement_address = (uint32_t) &end;
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void *program_break, *program_break_end;
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static uint32_t kmalloc_int(uint32_t sz, uint32_t align, uint32_t *phys) {
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if (program_break) {
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// 有内存堆
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void *addr = alloc(sz); // 直接malloc，align丢掉了
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if (phys) {
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// 需要物理地址，先找到对应页
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page_t *page = get_page((uint32_t) addr, 0, current_directory);
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*phys = page->frame * 0x1000 + ((uint32_t) addr & 0xfff);
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}
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return (uint32_t) addr;
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}
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if (align && (placement_address & 0x00000FFF)) {
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placement_address &= 0xFFFFF000;
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placement_address += 0x1000;
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}
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if (phys) *phys = placement_address;
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uint32_t tmp = placement_address;
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placement_address += sz;
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return tmp;
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}
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uint32_t kmalloc_a(uint32_t size) {
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return kmalloc_int(size, 1, 0);
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}
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uint32_t kmalloc_p(uint32_t size, uint32_t *phys) {
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return kmalloc_int(size, 0, phys);
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}
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uint32_t kmalloc_ap(uint32_t size, uint32_t *phys) {
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return kmalloc_int(size, 1, phys);
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}
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uint32_t kmalloc(uint32_t size) {
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return kmalloc_int(size, 0, 0);
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}
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void *ksbrk(int incr) {
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if (program_break == 0 || program_break + incr >= program_break_end) return (void *) -1;
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void *prev_break = program_break;
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program_break += incr;
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return prev_break;
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}
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// 寻找一个符合条件的指定大小的空闲内存块
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static header_t *get_free_block(uint32_t size) {
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header_t *curr = head;
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while (curr) {
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if (curr->s.is_free && curr->s.size >= size) return curr;
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curr = curr->s.next;
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}
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return NULL;
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}
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void *alloc(uint32_t size) {
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uint32_t total_size;
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void *block;
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header_t *header;
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if (!size) return NULL;
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header = get_free_block(size);
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if (header) {
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header->s.is_free = 0;
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return (void *) (header + 1);
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}
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total_size = sizeof(header_t) + size;
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block = ksbrk(total_size);
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if (block == (void *) -1) return NULL;
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header = block;
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header->s.size = size;
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header->s.is_free = 0;
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header->s.next = NULL;
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if (!head) head = header;
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if (tail) tail->s.next = header;
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tail = header;
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return (void *) (header + 1);
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}
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void kfree(void *block) {
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header_t *header, *tmp;
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if (!block) return;
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header = (header_t *) block - 1;
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if ((char *) block + header->s.size == program_break) {
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if (head == tail) head = tail = NULL;
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else {
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tmp = head;
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while (tmp) {
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if (tmp->s.next == tail) {
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tmp->s.next = NULL;
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tail = tmp;
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}
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tmp = tmp->s.next;
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}
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}
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ksbrk(0 - sizeof(header_t) - header->s.size);
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return;
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}
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header->s.is_free = 1;
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}
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