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/*
* Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <xfs/libxfs.h>
#include "bit.h"
#undef setbit /* defined in param.h on Linux */
static int getbit(char *ptr, int bit);
static void setbit(char *ptr, int bit, int val);
static int
getbit(
char *ptr,
int bit)
{
int mask;
int shift;
ptr += byteize(bit);
bit = bitoffs(bit);
shift = 7 - bit;
mask = 1 << shift;
return (*ptr & mask) >> shift;
}
static void
setbit(
char *ptr,
int bit,
int val)
{
int mask;
int shift;
ptr += byteize(bit);
bit = bitoffs(bit);
shift = 7 - bit;
mask = (1 << shift);
if (val) {
*ptr |= mask;
} else {
mask = ~mask;
*ptr &= mask;
}
}
__int64_t
getbitval(
void *obj,
int bitoff,
int nbits,
int flags)
{
int bit;
int i;
char *p;
__int64_t rval;
int signext;
int z1, z2, z3, z4;
ASSERT(nbits<=64);
p = (char *)obj + byteize(bitoff);
bit = bitoffs(bitoff);
signext = (flags & BVSIGNED) != 0;
z4 = ((__psint_t)p & 0xf) == 0 && bit == 0;
if (nbits == 64 && z4)
return be64_to_cpu(*(__be64 *)p);
z3 = ((__psint_t)p & 0x7) == 0 && bit == 0;
if (nbits == 32 && z3) {
if (signext)
return (__s32)be32_to_cpu(*(__be32 *)p);
else
return (__u32)be32_to_cpu(*(__be32 *)p);
}
z2 = ((__psint_t)p & 0x3) == 0 && bit == 0;
if (nbits == 16 && z2) {
if (signext)
return (__s16)be16_to_cpu(*(__be16 *)p);
else
return (__u16)be16_to_cpu(*(__be16 *)p);
}
z1 = ((__psint_t)p & 0x1) == 0 && bit == 0;
if (nbits == 8 && z1) {
if (signext)
return *(__s8 *)p;
else
return *(__u8 *)p;
}
for (i = 0, rval = 0LL; i < nbits; i++) {
if (getbit(p, bit + i)) {
/* If the last bit is on and we care about sign
* bits and we don't have a full 64 bit
* container, turn all bits on between the
* sign bit and the most sig bit.
*/
/* handle endian swap here */
#if __BYTE_ORDER == LITTLE_ENDIAN
if (i == 0 && signext && nbits < 64)
rval = -1LL << nbits;
rval |= 1LL << (nbits - i - 1);
#else
if ((i == (nbits - 1)) && signext && nbits < 64)
rval |= (-1LL << nbits);
rval |= 1LL << (nbits - i - 1);
#endif
}
}
return rval;
}
void
setbitval(
void *obuf, /* buffer to write into */
int bitoff, /* bit offset of where to write */
int nbits, /* number of bits to write */
void *ibuf) /* source bits */
{
char *in = (char *)ibuf;
char *out = (char *)obuf;
int bit;
#if BYTE_ORDER == LITTLE_ENDIAN
int big = 0;
#else
int big = 1;
#endif
/* only need to swap LE integers */
if (big || (nbits!=16 && nbits!=32 && nbits!=64) ) {
/* We don't have type info, so we can only assume
* that 2,4 & 8 byte values are integers. sigh.
*/
/* byte aligned ? */
if (bitoff%NBBY) {
/* no - bit copy */
for (bit=0; bit<nbits; bit++)
setbit(out, bit+bitoff, getbit(in, bit));
} else {
/* yes - byte copy */
memcpy(out+byteize(bitoff), in, byteize(nbits));
}
} else {
int ibit;
int obit;
/* we need to endian swap this value */
out+=byteize(bitoff);
obit=bitoffs(bitoff);
ibit=nbits-NBBY;
for (bit=0; bit<nbits; bit++) {
setbit(out, bit+obit, getbit(in, ibit));
if (ibit%NBBY==NBBY-1)
ibit-=NBBY*2-1;
else
ibit++;
}
}
}
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