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