harvey/sys/src/liboventi/packet.h

/*
 * This file is part of the UCB release of Plan 9. It is subject to the license
 * terms in the LICENSE file found in the top-level directory of this
 * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
 * part of the UCB release of Plan 9, including this file, may be copied,
 * modified, propagated, or distributed except according to the terms contained
 * in the LICENSE file.
 */

typedef struct Packet Packet;
typedef struct Mem Mem;
typedef struct Frag Frag;

enum {
	BigMemSize = MaxFragSize,
	SmallMemSize = BigMemSize/8,
	NLocalFrag = 2,
};

/* position to carve out of a Mem */
enum {
	PFront,
	PMiddle,
	PEnd,
};

struct Mem
{
	Lock lk;
	int ref;
	unsigned char *bp;
	unsigned char *ep;
	unsigned char *rp;
	unsigned char *wp;
	Mem *next;
};

enum {
	FragLocalFree,
	FragLocalAlloc,
	FragGlobal,
};
	
struct Frag
{
	int state;
	Mem *mem;
	unsigned char *rp;
	unsigned char *wp;
	Frag *next;
};

struct Packet
{
	int size;
	int asize;  /* allocated memmory - always greater than size */
	
	Packet *next;
	
	Frag *first;
	Frag *last;
	
	Frag local[NLocalFrag];
};