Potentially working bitmap allocator, still need to debug it, but i need to push this so i can switch machines.

include/physmem.h

@@ -7,6 +7,6 @@
 #define MEM_MAX 0xFFFFFFFF
 extern uint8_t* pmem_bitmap;
 
-void build_bitmap(mb_mmap_entry_t* mmap, int mmap_size);
+unsigned int build_bitmap(mb_mmap_entry_t* mmap, int mmap_size);
 
 #endif

src/io.c

@@ -84,6 +84,8 @@ int printf(char_writer_t* writer, const char* fmt, ...) {
                 //Integer definitions.
                 case 'X':
                     ret = print(writer, "0x");
+                    radix = 0x10;
+                    break;
                 case 'x':    
                     radix = 0x10;
                     break;

src/main.c

@@ -45,6 +45,7 @@ void kern_main(uint32_t multiboot_magic, mb_info_t* multiboot_info)
     } else {
         println(default_output, "Multiboot detected! Continuing...");
     }
+    printf(default_output, "MB_flags:%b\n", multiboot_info->flags);
     printf(default_output, "MEM_LOWER:%X\n", multiboot_info->mem_lower);
     printf(default_output, "MEM_UPPER:%X\n", multiboot_info->mem_upper);
     
@@ -55,10 +56,9 @@ void kern_main(uint32_t multiboot_magic, mb_info_t* multiboot_info)
         return;
     }
 
-    printf(default_output, "lol:%X\n", multiboot_info->flags);
-    
-    build_bitmap((mb_mmap_entry_t*)multiboot_info->mmap_addr, multiboot_info->mmap_length);
     
+    unsigned int pages_allocated = build_bitmap((mb_mmap_entry_t*)multiboot_info->mmap_addr, multiboot_info->mmap_length);
+    printf(default_output, "Available mem:%d Pages | %dK", pages_allocated, pages_allocated * PAGE_SIZE);
 
 
 }

src/physmem.c

@@ -5,11 +5,11 @@
 uint8_t* pmem_bitmap;
 
 
-void build_bitmap(mb_mmap_entry_t* mmap, int mmap_size) {
+unsigned int build_bitmap(mb_mmap_entry_t* mmap, int mmap_size) {
-    
+    unsigned int pages_allocated = 0;    
     //Set up a bitmap and set it all to 1
     pmem_bitmap = &_kernel_end;
-    unsigned int bitmap_end = (unsigned int)pmem_bitmap + (MEM_MAX / (PAGE_SIZE*8));
+    uint32_t bitmap_end = (uint32_t)pmem_bitmap + (MEM_MAX / (PAGE_SIZE*8));
     printf(default_output, "bitmap at: %X", pmem_bitmap);
     for(unsigned int i = 0; i < bitmap_end; i++) {
         *(pmem_bitmap + i) = 0xFF;
@@ -24,7 +24,7 @@ void build_bitmap(mb_mmap_entry_t* mmap, int mmap_size) {
         printf(default_output,"__MMAP_ENTRY__:\nSTART_ADDR:%X\nSIZE:%X\nTYPE:%u\n",(uint32_t)mmap->addr, (uint32_t)mmap->mem_size, mmap->type);
 
 
-        uint8_t* mem_bottom =(uint8_t*) (((int)mmap->addr + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1));
+        uint8_t* mem_bottom =(uint8_t*) (((uint32_t)mmap->addr + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1));
 
         if(mmap->type != 1) {
             //nah...
@@ -32,7 +32,7 @@ void build_bitmap(mb_mmap_entry_t* mmap, int mmap_size) {
         }
     
         //round the starting address of the map to the nearest page boundary so we don't mark half used pages as free
-        uint8_t* mem_top = (uint8_t*) (((int)mmap->addr + mmap->mem_size) & ~(PAGE_SIZE - 1));
+        uint8_t* mem_top = (uint8_t*) (((uint32_t)mmap->addr + (uint32_t)mmap->mem_size) & ~(PAGE_SIZE - 1));
 
 
         printf(default_output, "lowerpage:%X|upper:%X\n", mem_bottom, mem_top);
@@ -49,23 +49,29 @@ void build_bitmap(mb_mmap_entry_t* mmap, int mmap_size) {
             *(pmem_bitmap + (unsigned int)i) = 0; 
         }
         */
-        for(int i = 0; i < mem_top - mem_bottom; i++){
+        int page_count = (mem_top - mem_bottom) / PAGE_SIZE;
+        for(int i = 0; i < page_count; i++){
             
-            if(mem_bottom + (PAGE_SIZE * i) < bitmap_end) { 
+            //OK which page is this
+            uint8_t* page_addr = mem_bottom + (PAGE_SIZE * i);
+            
+            if((uint32_t)page_addr < bitmap_end) { 
+                //bruh this is in lowmem or the kernel
                 continue;
             }
             
-            //OK to allocate one page.
+            //Available. Calculate the offset of the bit on the bitmap based on the page address
-            //wtf am i doing. sleep on it.
+            unsigned int pagenumber = (unsigned int)page_addr / PAGE_SIZE;
-            int shift = i%8;
+            uint8_t* bitmap_byte = pmem_bitmap + (pagenumber / 8); 
-            *(pmem_bitmap) &= ~(0x80 >> i);
+            int bitmap_bit = pagenumber % 8;
-            if(!*pmem_bitmap == 7) {
-                
-            }
 
+            //ok now set the bit to unused
+            *bitmap_byte &= ~(0x80 >> bitmap_bit);
+            pages_allocated++;
         }
         
     } 
    
+    return pages_allocated;
     
 }