90 lines
2.0 KiB
C
90 lines
2.0 KiB
C
#include "mem.h"
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#include "list.h"
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#include "types.h"
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#include "vga.h"
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static struct mem_desc *page_desc = (struct mem_desc *)&__ld_kernel_end;
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static struct mem_desc *free_page;
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static struct mem_desc *used_page;
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static unsigned long bottom_mem;
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static unsigned long top_mem;
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int memSetup(unsigned long upper_mem)
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{
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// Align upper mem (in kB) on page size even if it does loose a page
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upper_mem = ALIGN_DOWN(upper_mem, PAGE_SIZE / 1024);
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printf("Available Mem from %d to %d \n", &__ld_kernel_end, upper_mem * 1024);
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// Memory description is stored after the kernel. We need some place to store it
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unsigned long memdesc_end =
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(unsigned long)page_desc +
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((upper_mem) / (PAGE_SIZE / 1024)) * sizeof(struct mem_desc);
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uint lastUsed = (memdesc_end >> PAGE_SHIFT) + 1;
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list_init(free_page);
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list_init(used_page);
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bottom_mem = lastUsed;
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top_mem = upper_mem * 1024;
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for (uint i = 0; i < (upper_mem / (PAGE_SIZE / 1024)); i++) {
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struct mem_desc *mem = &page_desc[i];
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if (i < lastUsed) {
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mem->ref = 1;
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list_add_tail(used_page, mem);
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} else {
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mem->ref = 0;
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list_add_tail(free_page, mem);
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}
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mem->phy_addr = i * PAGE_SIZE;
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}
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return 0;
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}
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struct mem_desc *addr2memDesc(paddr_t addr)
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{
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if (addr > top_mem || addr < bottom_mem)
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return NULL;
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int idx = addr >> PAGE_SHIFT;
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return page_desc + idx;
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}
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paddr_t allocPhyPage(void)
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{
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if (list_is_empty(free_page)) {
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return (unsigned long)NULL;
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}
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struct mem_desc *mem = list_pop_head(free_page);
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mem->ref = 1;
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list_add_tail(used_page, mem);
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return mem->phy_addr;
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}
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int unrefPhyPage(paddr_t addr)
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{
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struct mem_desc *mem = addr2memDesc(addr);
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if (!mem) {
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return -1;
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}
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mem->ref--;
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if (mem->ref == 0) {
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list_delete(used_page, mem);
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list_add_tail(free_page, mem);
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}
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return 0;
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}
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int refPhyPage(paddr_t addr)
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{
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struct mem_desc *mem = addr2memDesc(addr);
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if (!mem) {
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return -1;
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}
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mem->ref++;
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if (mem->ref == 1) {
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list_add_tail(used_page, mem);
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list_delete(free_page, mem);
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}
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return 0;
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}
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