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Do the unaligned buffer fixup without copying data, more-or-less lifted

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from the Shark CS8900 driver.
This commit is contained in:
thorpej 1998-06-10 01:15:50 +00:00
parent a90d5cd12e
commit 4ad627c09b
1 changed files with 58 additions and 47 deletions
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105
sys/dev/ic/ne2000.c
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@ -1,4 +1,4 @@
/* $NetBSD: ne2000.c,v 1.11 1998/02/04 14:13:40 sakamoto Exp $ */
/* $NetBSD: ne2000.c,v 1.12 1998/06/10 01:15:50 thorpej Exp $ */
/*-
* Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@ -455,60 +455,71 @@ ne2000_write_mbuf(sc, m, buf)
}
} else {
/* NE2000s are a bit trickier. */
u_int8_t *data, *aligndata, savebyte[2];
int l, wantbyte;
u_int8_t *data, savebyte[2];
int l, leftover;
#ifdef DIAGNOSTIC
u_int8_t *lim;
#endif
/* Start out with no leftover data. */
leftover = 0;
savebyte[0] = savebyte[1] = 0;
wantbyte = 0;
for (; m != 0; m = m->m_next) {
l = m->m_len;
if (l == 0)
continue;
data = mtod(m, u_int8_t *);
aligndata = NULL;
/* Finish the last word. */
if (wantbyte) {
savebyte[1] = *data;
bus_space_write_stream_2(asict, asich,
NE2000_ASIC_DATA, *(u_int16_t *)savebyte);
data++;
l--;
wantbyte = 0;
#ifdef DIAGNOSTIC
lim = data + l;
#endif
while (l > 0) {
if (leftover) {
/*
* Data left over (from mbuf or
* realignment). Buffer the next
* byte, and write it and the
* leftover data out.
*/
savebyte[1] = *data++;
l--;
bus_space_write_stream_2(asict, asich,
NE2000_ASIC_DATA,
*(u_int16_t *)savebyte);
leftover = 0;
} else if (ALIGNED_POINTER(data,
u_int16_t) == 0) {
/*
* Unaligned data; buffer the next
* byte.
*/
savebyte[0] = *data++;
l--;
leftover = 1;
} else {
/*
* Aligned data; output contiguous
* words as much as we can, then
* buffer the remaining byte, if any.
*/
leftover = l & 1;
l &= ~1;
bus_space_write_multi_stream_2(asict,
asich, NE2000_ASIC_DATA,
(u_int16_t *)data, l >> 1);
data += l;
if (leftover)
savebyte[0] = *data++;
l = 0;
}
}
/*
* If the previous mbuf was odd length, the
* above check will have misaligned the rest
* of the current mbuf. If this is the case,
* we need to use a temporary buffer.
*/
if (ALIGNED_POINTER(data, u_int16_t) == 0) {
aligndata = malloc(l, M_DEVBUF, M_NOWAIT);
if (aligndata == NULL)
panic("ne2000_write_mbuf: can't get "
"temporary buffer"); /* XXX */
bcopy(data, aligndata, l);
data = aligndata;
}
/* Output contiguous words. */
if (l > 1) {
bus_space_write_multi_stream_2(asict, asich,
NE2000_ASIC_DATA, (u_int16_t *)data,
l >> 1);
}
/* Save last byte, if necessary. */
if (l & 1) {
data += l & ~1;
savebyte[0] = *data;
wantbyte = 1;
}
if (aligndata != NULL)
free(aligndata, M_DEVBUF);
if (l < 0)
panic("ne2000_write_mbuf: negative len");
#ifdef DIAGNOSTIC
if (data != lim)
panic("ne2000_write_mbuf: data != lim");
#endif
}
if (wantbyte) {
if (leftover) {
savebyte[1] = 0;
bus_space_write_stream_2(asict, asich, NE2000_ASIC_DATA,
*(u_int16_t *)savebyte);