Implementation of simplistic physical memory manager

src/kernel/memory/PhysicalMemoryManager.cpp

@@ -0,0 +1,118 @@
+#include "PhysicalMemoryManager.h"
+
+size_t mem_size = 0;
+int used_blocks = 0;
+size_t max_blocks = 0;
+uint32_t* pmmap = 0;
+size_t pmmap_size = 0; 
+
+
+void PhysicalMemoryManager_initialise(uint32_t physicalmemorymap_address, size_t size )
+{
+    mem_size = size;
+    max_blocks = KB_TO_BLOCKS(mem_size);
+
+    used_blocks = max_blocks;
+
+    pmmap = (uint32_t*) physicalmemorymap_address;
+
+    if(max_blocks % BLOCKS_PER_WORD)
+        pmmap_size++;
+    
+    memset(pmmap, 0xFF, pmmap_size);
+}
+
+void PhysicalMemoryManager_region_initialise(uint32_t base, size_t size)
+{
+    size_t blocks = size /BLOCK_SIZE;
+    uint32_t align = base / BLOCK_SIZE;
+
+    for(size_t i = 0 ; i < blocks; i ++)
+    {
+        bitmap_unset(pmmap, align++);
+        used_blocks--;
+    }
+
+    bitmap_set(pmmap, 0);
+
+}
+
+void PhysicalMemoryManager_region_deinitialise(uint32_t base, size_t size )
+{
+    size_t blocks = size / BLOCK_SIZE;
+    uint32_t align = base / BLOCK_SIZE;
+
+    for(size_t i = 0 ; i < blocks; i++ )
+    {
+        bitmap_set(pmmap, align++);
+        used_blocks++;
+    }
+
+
+}
+
+void PhysicalMemoryManager_initialise_available_regions(uint32_t mmap_, uint32_t mmap_end_)
+{
+    multiboot_memory_map_t *mmap = (multiboot_memory_map_t*)mmap_;
+    multiboot_memory_map_t *mmap_end= (multiboot_memory_map_t*) mmap_end_;
+
+    for(int i = 0; mmap < mmap_end ; mmap++, i++)
+    {   
+        if(mmap->type == MULTIBOOT_MEMORY_AVAILABLE)
+        {
+            PhysicalMemoryManager_region_initialise((uint32_t) mmap->addr, (size_t) mmap->len);
+        }
+    }
+
+}
+
+void PhysicalMemoryManager_deinitialise_kernel()
+{
+    extern uint8_t kernel_begin;
+    extern uint8_t kernel_end;
+
+    size_t kernel_size = (size_t) &kernel_end - (size_t) &kernel_begin;
+
+    uint32_t pmmap_size_aligned = pmmap_size;
+    if(!IS_ALIGNED(pmmap_size_aligned, BLOCK_SIZE))
+    {
+        pmmap_size_aligned = ALIGN(pmmap_size_aligned, BLOCK_SIZE);
+    }
+    
+    PhysicalMemoryManager_region_deinitialise((uint32_t) &kernel_begin, kernel_size);
+    PhysicalMemoryManager_region_deinitialise((uint32_t) &kernel_end, pmmap_size_aligned);
+    
+}
+
+void* PhysicalMemoryManager_allocate_block()
+{
+    if(used_blocks - max_blocks <= 0)
+    {
+        return 0;
+    }
+
+    int p_index = bitmap_first_unset(pmmap, p_index );
+
+    if(p_index == -1){
+        return 0;
+    }
+
+    bitmap_set(pmmap, p_index);
+    used_blocks++;
+
+    return (void*) (BLOCK_SIZE * p_index);
+}
+
+void PhysicalMemoryManager_free_block(void* p){
+    if(p==0){
+        return ;
+    }
+
+    uint32_t p_addr = (uint32_t) p;
+
+    int index  = p_addr / BLOCK_SIZE;
+    bitmap_unset(pmmap, index);
+
+    used_blocks--;
+
+}

src/kernel/memory/PhysicalMemoryManager.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include "../bootloader/multiboot.h"
+#include <stdint.h>
+#include <stddef.h>
+#include "../../libc/include/mem.h"
+#include "../kstructures/bitmap.h"
+
+
+#define BLOCK_SIZE 4092
+#define BLOCKS_PER_WORD 32
+
+#define KB_TO_BLOCKS(x) (((x) * 1024 ) / BLOCK_SIZE)
+#define IS_ALIGNED(addr, align) !((addr) & ~((align) - 1))
+#define ALIGN(addr, align) (((addr) & ~((align) - 1 )) + (align))
+
+
+extern void PhysicalMemoryManager_initialise(uint32_t, size_t);
+
+extern void PhysicalMemoryManager_region_initialise(uint32_t, size_t);
+extern void PhysicalMemoryManager_region_deinitialise(uint32_t,size_t);
+
+extern void PhysicalMemoryManager_initialise_available_regions(uint32_t, uint32_t);
+extern void PhysicalMemoryManager_deinitialise_kernel();
+
+extern void* PhysicalMemoryManager_allocate_block();
+extern void PhysicalMemoryManager_free_block(void* p);
+
+
+extern size_t mem_size;
+extern int used_blocks;
+extern size_t max_blocks;
+extern uint32_t* pmmap;
+extern size_t pmmap_size ;