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#include "kernel.h"
#include "kmalloc.h"
#include "spinlock.h"
#include "log.h"
#define BLOCKS KMALLOC_MEM_SIZE/KMALLOC_BLOCK_SIZE
// this is in .bss so we can assume it was zeroed!
static uint8_t data[KMALLOC_MEM_SIZE] __attribute__((aligned (4096))); // bytes
static uint8_t map[BLOCKS];
//
static uint32_t data_addr;
static uint32_t next;
static uint32_t first;
static uint8_t init=0;
static uint32_t next_free(uint32_t start)
{
for(int i=start;i<BLOCKS;i++)
{
if(!map[i])return i;
return next_free(i+map[i]);
}
return BLOCKS; // out of mem
}
static uint32_t next_used(uint32_t start,uint32_t max)
{
for(int i=start;i<BLOCKS;i++)
{
if(map[i])return i;
//means i is free
if(i-start>=max)return i;
}
return BLOCKS; // all free
}
static uint32_t free_cont(uint32_t blocks)
{
uint32_t pos=0;
while(1)
{
pos=next_free(pos);
// klog("next_free:%d",pos);
if(pos==BLOCKS)return BLOCKS; // out of mem
uint32_t end=next_used(pos,blocks);
// klog("next_used:%d",end);
if(end-pos>=blocks)return pos;
// klog("here we have only %d blocks but we need at least %d",end-pos+1,blocks);
pos=end;
}
}
static void mark_used(uint32_t start,uint32_t blocks)
{
uint32_t b=blocks;
for(int i=start;i<start+blocks;i++)
{
if(map[i]!=0)kpanic("memory map corrupted?");
map[i]=b;
b--;
}
}
static void mark_free(uint32_t start,uint32_t blocks)
{
if(map[start]!=blocks)
{
kpanic("mark_free(%d,%d),mem map corrupted at %d (value=%d)?",start,blocks,start,map[start]);
}
if(start!=0&&(map[start-1]!=1&&map[start-1]!=0))
{
kpanic("mem map corrupted one before %d (value=%d)?",start,map[start-1]);
}
map[start]=0;
if(blocks>1)mark_free(start+1,blocks-1);
}
// will be initialized on first call to kballoc() //
static void kmallocinit()
{
next=&(data[0]);
data_addr=next;
first=next;
if(next%4096)kpanic("kmalloc data not aligned properly.");
klog("In-Kernel Block Memory Allocation Initialized at: 0x%08X (free: %d x 4096KB BLOCKS)",next,BLOCKS);
init=1;
}
// kernel block memory allocation //
uint32_t kballoc(uint32_t size)
{
if(size>255)kpanic("max supported size 255 blocks");
spinlock_spin(SPINLOCK_ALLOC);
if(!init)kmallocinit();
uint32_t blk=free_cont(size);
if(blk==BLOCKS)kpanic("out of mem");
mark_used(blk,size);
spinlock_release(SPINLOCK_ALLOC);
return data_addr+blk*4096;
}
void kbfree(uint32_t pos)
{
uint32_t blk=(pos-data_addr)/4096;
spinlock_spin(SPINLOCK_ALLOC);
klog("freeing %d blocks ad 0x%08X",map[blk],pos);
mark_free(blk,map[blk]);
spinlock_release(SPINLOCK_ALLOC);
}
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