target-ppc: fix mtfsb0 and mtfsb1
[qemu/mini2440.git] / slirp / mbuf.c
blob655de41805c22b17b8679283a288e2a0e23aa07d
1 /*
2 * Copyright (c) 1995 Danny Gasparovski
4 * Please read the file COPYRIGHT for the
5 * terms and conditions of the copyright.
6 */
8 /*
9 * mbuf's in SLiRP are much simpler than the real mbufs in
10 * FreeBSD. They are fixed size, determined by the MTU,
11 * so that one whole packet can fit. Mbuf's cannot be
12 * chained together. If there's more data than the mbuf
13 * could hold, an external malloced buffer is pointed to
14 * by m_ext (and the data pointers) and M_EXT is set in
15 * the flags
18 #include <slirp.h>
20 int mbuf_alloced = 0;
21 struct mbuf m_freelist, m_usedlist;
22 #define MBUF_THRESH 30
23 int mbuf_max = 0;
26 * Find a nice value for msize
27 * XXX if_maxlinkhdr already in mtu
29 #define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6)
31 void
32 m_init()
34 m_freelist.m_next = m_freelist.m_prev = &m_freelist;
35 m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist;
39 * Get an mbuf from the free list, if there are none
40 * malloc one
42 * Because fragmentation can occur if we alloc new mbufs and
43 * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,
44 * which tells m_free to actually free() it
46 struct mbuf *
47 m_get()
49 register struct mbuf *m;
50 int flags = 0;
52 DEBUG_CALL("m_get");
54 if (m_freelist.m_next == &m_freelist) {
55 m = (struct mbuf *)malloc(SLIRP_MSIZE);
56 if (m == NULL) goto end_error;
57 mbuf_alloced++;
58 if (mbuf_alloced > MBUF_THRESH)
59 flags = M_DOFREE;
60 if (mbuf_alloced > mbuf_max)
61 mbuf_max = mbuf_alloced;
62 } else {
63 m = m_freelist.m_next;
64 remque(m);
67 /* Insert it in the used list */
68 insque(m,&m_usedlist);
69 m->m_flags = (flags | M_USEDLIST);
71 /* Initialise it */
72 m->m_size = SLIRP_MSIZE - sizeof(struct m_hdr);
73 m->m_data = m->m_dat;
74 m->m_len = 0;
75 m->m_nextpkt = 0;
76 m->m_prevpkt = 0;
77 end_error:
78 DEBUG_ARG("m = %lx", (long )m);
79 return m;
82 void
83 m_free(m)
84 struct mbuf *m;
87 DEBUG_CALL("m_free");
88 DEBUG_ARG("m = %lx", (long )m);
90 if(m) {
91 /* Remove from m_usedlist */
92 if (m->m_flags & M_USEDLIST)
93 remque(m);
95 /* If it's M_EXT, free() it */
96 if (m->m_flags & M_EXT)
97 free(m->m_ext);
100 * Either free() it or put it on the free list
102 if (m->m_flags & M_DOFREE) {
103 free(m);
104 mbuf_alloced--;
105 } else if ((m->m_flags & M_FREELIST) == 0) {
106 insque(m,&m_freelist);
107 m->m_flags = M_FREELIST; /* Clobber other flags */
109 } /* if(m) */
113 * Copy data from one mbuf to the end of
114 * the other.. if result is too big for one mbuf, malloc()
115 * an M_EXT data segment
117 void
118 m_cat(m, n)
119 register struct mbuf *m, *n;
122 * If there's no room, realloc
124 if (M_FREEROOM(m) < n->m_len)
125 m_inc(m,m->m_size+MINCSIZE);
127 memcpy(m->m_data+m->m_len, n->m_data, n->m_len);
128 m->m_len += n->m_len;
130 m_free(n);
134 /* make m size bytes large */
135 void
136 m_inc(m, size)
137 struct mbuf *m;
138 int size;
140 int datasize;
142 /* some compiles throw up on gotos. This one we can fake. */
143 if(m->m_size>size) return;
145 if (m->m_flags & M_EXT) {
146 datasize = m->m_data - m->m_ext;
147 m->m_ext = (char *)realloc(m->m_ext,size);
148 /* if (m->m_ext == NULL)
149 * return (struct mbuf *)NULL;
151 m->m_data = m->m_ext + datasize;
152 } else {
153 char *dat;
154 datasize = m->m_data - m->m_dat;
155 dat = (char *)malloc(size);
156 /* if (dat == NULL)
157 * return (struct mbuf *)NULL;
159 memcpy(dat, m->m_dat, m->m_size);
161 m->m_ext = dat;
162 m->m_data = m->m_ext + datasize;
163 m->m_flags |= M_EXT;
166 m->m_size = size;
172 void
173 m_adj(m, len)
174 struct mbuf *m;
175 int len;
177 if (m == NULL)
178 return;
179 if (len >= 0) {
180 /* Trim from head */
181 m->m_data += len;
182 m->m_len -= len;
183 } else {
184 /* Trim from tail */
185 len = -len;
186 m->m_len -= len;
192 * Copy len bytes from m, starting off bytes into n
195 m_copy(n, m, off, len)
196 struct mbuf *n, *m;
197 int off, len;
199 if (len > M_FREEROOM(n))
200 return -1;
202 memcpy((n->m_data + n->m_len), (m->m_data + off), len);
203 n->m_len += len;
204 return 0;
209 * Given a pointer into an mbuf, return the mbuf
210 * XXX This is a kludge, I should eliminate the need for it
211 * Fortunately, it's not used often
213 struct mbuf *
214 dtom(dat)
215 void *dat;
217 struct mbuf *m;
219 DEBUG_CALL("dtom");
220 DEBUG_ARG("dat = %lx", (long )dat);
222 /* bug corrected for M_EXT buffers */
223 for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) {
224 if (m->m_flags & M_EXT) {
225 if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) )
226 return m;
227 } else {
228 if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) )
229 return m;
233 DEBUG_ERROR((dfd, "dtom failed"));
235 return (struct mbuf *)0;