wm: teppich

ref: 48cc33b5b8717b83c4dea9130c4396b451480c56
dir: /pc/mem.c/

#include <u.h>
#include <libc.h>
#include <mem.h>
#include <err.h>

/* does first fit, returns index of that part of memory in memap */
int
_malloc(uint16 size)
{
	int i, j;
	uint16 fmem; /* number of free segments */

	if(size > MEM_MAX * BLOCKSIZE)
		return NO_MEM;

	i = 0;
	fmem = 0;
	while(i < MEM_MAX * (1024 / BLOCKSIZE))
	{
		if(memap[i] == FREE)
		{
			fmem++;
			if(fmem == size+1) /* one bit for padding */
			{
	
				/* we are done here, give address */
				for(j = i ; j > i - size; j--)
					memap[j] = TAKEN;
			 	return i - size;
			}
		}
		else
		{
			fmem = 0; /* we need contigus(?) memory */
		}
		i++;
	}	

	
	return NO_MEM;
}

void*
malloc(uint16 size)
{
	int t;
	
	if(size == 0)
		return nil;

	t = _malloc(size);
	if(t == NO_MEM)
		return nil;

	return (void*)(t * ( BLOCKSIZE ) + MEM_BEG);
}

int
free(void *mem)
{
	int i;

	i = (((int)(mem) - MEM_BEG ) / BLOCKSIZE)+1;
	while(memap[i])
	{
		memap[i] = 0;
		*(char*)mem++ = '\0';
		i++;
	}
	return OK;
}