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Completed kheap and added some parts of paging.h

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ice-bit
2019-09-23 12:23:50 +02:00
parent 07eff0e48c
commit 3eacf3ea21
4 changed files with 182 additions and 3 deletions
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56
kernel/drivers/paging.c Normal file
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#include "paging.h"
// Macros for bitset algorithms
#define INDEX_FROM_BIT(a) (a/(8*4))
#define OFFSET_FROM_BIT(a) (a%(8*4))
// Kernel's page directory
page_directory_t *kernel_directory = 0;
// Current page directory
page_directory_t *current_directory = 0;
// Bitset of frames, used or free
uint32_t *frames;
uint32_t nframes;
// From kheap.c
extern uint32_t placement_address;
extern heap_t *kheap;
// Set a bit in the frame bitset
static void set_frame(uint32_t frame_addr) {
uint32_t frame = frame_addr / 0x1000;
uint32_t idx = INDEX_FROM_BIT(frame);
uint32_t off = OFFSET_FROM_BIT(frame);
frames[idx] |= (0x1 << off);
}
// clear a bit in the frame bitset
static void clear_frame(uint32_t frame_addr) {
uint32_t frame = frame_addr / 0x1000;
uint32_t idx = INDEX_FROM_BIT(frame);
uint32_t off = OFFSET_FROM_BIT(frame);
frames[idx] &= ~(0x1 << off);
}
// Test if a bit is set
static uint32_t test_frame(uint32_t frame_addr) {
uint32_t frame = frame_addr / 0x1000;
uint32_t idx = INDEX_FROM_BIT(frame);
uint32_t off = OFFSET_FROM_BIT(frame);
return (frames[idx] & (0x1 << off));
}
// Find the first three frames
static uint32_t first_frame() {
for(uint32_t i = 0; i < INDEX_FROM_BIT(nframes); i++) {
if(frames[i] != 0xFFFFFFFF) { // If nothing is free, exit
for(uint32_t j = 0; j < 32; j++) {
uint32_t to_test = 0x1 << j;
if (!(frames[i]&to_test))
return i*4*8+j;
}
}
}
}