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/*
** File: netbuff.c Jun. 10, 2000
**
** Author: Giovanni Falzoni <gfalzoni@inwind.it>
**
** This file contains specific implementation of buffering
** for network packets.
*/
#include <minix/drivers.h>
#include <minix/netdriver.h>
#include "dp.h"
#if (HAVE_BUFFERS == 1)
static m_hdr_t *allocptr = NULL;
static char tx_rx_buff[8192];
/*
** Name: alloc_buff
** Function: Allocates a buffer from the common pool.
*/
void *alloc_buff(dpeth_t *dep, int size)
{
m_hdr_t *ptr, *wrk = allocptr;
int units = ((size + sizeof(m_hdr_t) - 1) / sizeof(m_hdr_t)) + 1;
for (ptr = wrk->next;; wrk = ptr, ptr = ptr->next) {
if (ptr->size >= units) {
/* Memory is available, carve requested size from pool */
if (ptr->size == units) {
wrk->next = ptr->next;
} else {
/* Get memory from top address */
ptr->size -= units;
ptr += ptr->size;
ptr->size = units;
}
allocptr = wrk;
return ptr + 1;
}
if (ptr == allocptr) break;
}
return NULL; /* No memory available */
}
/*
** Name: free_buff
** Function: Returns a buffer to the common pool.
*/
void free_buff(dpeth_t *dep, void *blk)
{
m_hdr_t *wrk, *ptr = (m_hdr_t *) blk - 1;
/* Scan linked list for the correct place */
for (wrk = allocptr; !(ptr > wrk && ptr < wrk->next); wrk = wrk->next)
if (wrk >= wrk->next && (ptr > wrk || ptr < wrk->next)) break;
/* Check if adjacent block is free and join blocks */
if (ptr + ptr->size == wrk->next) {
ptr->size += wrk->next->size;
ptr->next = wrk->next->next;
} else
ptr->next = wrk->next;
if (wrk + wrk->size == ptr) {
wrk->size += ptr->size;
wrk->next = ptr->next;
} else
wrk->next = ptr;
allocptr = wrk; /* Point allocptr to block just released */
}
/*
** Name: init_buff
** Function: Initalizes driver data structures.
*/
void init_buff(dpeth_t *dep, buff_t **tx_buff)
{
/* Initializes buffer pool */
if (allocptr == NULL) {
m_hdr_t *rx = (m_hdr_t *) tx_rx_buff;
rx->next = allocptr = rx;
rx->size = 0;
rx += 1;
rx->next = NULL;
rx->size = (sizeof(tx_rx_buff) / sizeof(m_hdr_t)) - 1;
free_buff(dep, rx + 1);
dep->de_recvq_tail = dep->de_recvq_head = NULL;
if (tx_buff != NULL) {
*tx_buff = alloc_buff(dep,
NDEV_ETH_PACKET_MAX + sizeof(buff_t));
(*tx_buff)->size = 0;
}
}
}
#endif /* HAVE_BUFFERS */
/** netbuff.c **/
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