mirror of https://github.com/E-Almqvist/eOS
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
70 lines
1.6 KiB
70 lines
1.6 KiB
#include "memory.h"
|
|
#include "../drivers/vga.h"
|
|
|
|
// https://wiki.osdev.org/Page_Frame_Allocation
|
|
// page = block
|
|
|
|
// MAX_BLOCK_SIZE_IN_BITS/8 bytes
|
|
// i.e. : bit i of byte n define status of block 8n+i
|
|
// block = 8n+i
|
|
|
|
// in 32-bit mode, we have access to 2^32 blocks
|
|
// which is (2^32)*BLOCK_SIZE blocks
|
|
// and with a blocksize of 1024, we git around 4.3 trillion blocks
|
|
// which is more than enough
|
|
|
|
#define CHECK_BITMAP(map, idx) ((map) & (1<<(idx)))
|
|
|
|
#define BLOCK_TO_MEMP(idx) (int*)(PM_MEM_START + (idx*BLOCK_SIZE))
|
|
|
|
|
|
static int bitmap = 0;
|
|
static uint last_block;
|
|
void mod_bitmap(uint bit, uint bflag) {
|
|
// create a bitmask that will be applied to the bitmap
|
|
int bitmask = 1 << bit;
|
|
|
|
// apply the bitmask, resulting in the bit:n bit will set
|
|
// set to bflag
|
|
bitmap = (((bitmap & ~bitmask)) | (bflag << bit));
|
|
}
|
|
|
|
|
|
int* block_alloc(uint blockidx) {
|
|
int block_bflag;
|
|
block_bflag = CHECK_BITMAP(bitmap, blockidx);
|
|
|
|
if( block_bflag == BM_FREE ) { // check if block is free
|
|
println("Alloc!", DEFAULT_COLOR);
|
|
|
|
mod_bitmap(blockidx, 1);
|
|
last_block = blockidx;
|
|
|
|
return BLOCK_TO_MEMP(blockidx); // placeholder
|
|
} else {
|
|
println("ERROR! Attemped to allocate non-free block.", 0x0c);
|
|
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
void block_free(uint blockidx) {
|
|
println("Dealloc block...", DEFAULT_COLOR);
|
|
mod_bitmap(blockidx, BM_FREE);
|
|
last_block = blockidx;
|
|
}
|
|
|
|
void pm_alloc_range(uint start, uint end, bool force) {
|
|
uint idx_start;
|
|
uint idx_end;
|
|
|
|
// calculate idx_start and idx_end
|
|
// if not force, check if avaliable
|
|
// allocate (if permitted)
|
|
}
|
|
|
|
/*
|
|
int* pm_malloc(uint block_count) {
|
|
|
|
}
|
|
*/
|
|
|