1 /* 2 ** File: netbuff.c Jun. 10, 2000 3 ** 4 ** Author: Giovanni Falzoni <gfalzoni@inwind.it> 5 ** 6 ** This file contains specific implementation of buffering 7 ** for network packets. 8 */ 9 10 #include <minix/drivers.h> 11 #include <minix/netdriver.h> 12 #include "dp.h" 13 14 #if (HAVE_BUFFERS == 1) 15 16 static m_hdr_t *allocptr = NULL; 17 static char tx_rx_buff[8192]; 18 19 /* 20 ** Name: alloc_buff 21 ** Function: Allocates a buffer from the common pool. 22 */ 23 void *alloc_buff(dpeth_t *dep, int size) 24 { 25 m_hdr_t *ptr, *wrk = allocptr; 26 int units = ((size + sizeof(m_hdr_t) - 1) / sizeof(m_hdr_t)) + 1; 27 28 for (ptr = wrk->next;; wrk = ptr, ptr = ptr->next) { 29 if (ptr->size >= units) { 30 /* Memory is available, carve requested size from pool */ 31 if (ptr->size == units) { 32 wrk->next = ptr->next; 33 } else { 34 /* Get memory from top address */ 35 ptr->size -= units; 36 ptr += ptr->size; 37 ptr->size = units; 38 } 39 allocptr = wrk; 40 return ptr + 1; 41 } 42 if (ptr == allocptr) break; 43 } 44 return NULL; /* No memory available */ 45 } 46 47 /* 48 ** Name: free_buff 49 ** Function: Returns a buffer to the common pool. 50 */ 51 void free_buff(dpeth_t *dep, void *blk) 52 { 53 m_hdr_t *wrk, *ptr = (m_hdr_t *) blk - 1; 54 55 /* Scan linked list for the correct place */ 56 for (wrk = allocptr; !(ptr > wrk && ptr < wrk->next); wrk = wrk->next) 57 if (wrk >= wrk->next && (ptr > wrk || ptr < wrk->next)) break; 58 59 /* Check if adjacent block is free and join blocks */ 60 if (ptr + ptr->size == wrk->next) { 61 ptr->size += wrk->next->size; 62 ptr->next = wrk->next->next; 63 } else 64 ptr->next = wrk->next; 65 if (wrk + wrk->size == ptr) { 66 wrk->size += ptr->size; 67 wrk->next = ptr->next; 68 } else 69 wrk->next = ptr; 70 allocptr = wrk; /* Point allocptr to block just released */ 71 } 72 73 /* 74 ** Name: init_buff 75 ** Function: Initalizes driver data structures. 76 */ 77 void init_buff(dpeth_t *dep, buff_t **tx_buff) 78 { 79 80 /* Initializes buffer pool */ 81 if (allocptr == NULL) { 82 m_hdr_t *rx = (m_hdr_t *) tx_rx_buff; 83 rx->next = allocptr = rx; 84 rx->size = 0; 85 rx += 1; 86 rx->next = NULL; 87 rx->size = (sizeof(tx_rx_buff) / sizeof(m_hdr_t)) - 1; 88 free_buff(dep, rx + 1); 89 dep->de_recvq_tail = dep->de_recvq_head = NULL; 90 if (tx_buff != NULL) { 91 *tx_buff = alloc_buff(dep, 92 NDEV_ETH_PACKET_MAX + sizeof(buff_t)); 93 (*tx_buff)->size = 0; 94 } 95 } 96 } 97 98 #endif /* HAVE_BUFFERS */ 99 100 /** netbuff.c **/ 101