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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 1998-2016. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
#include <string.h>
#include "eidef.h"
#include "eiext.h"
#include "putget.h"
static void copy_bits(const unsigned char* src, size_t soffs,
unsigned char* dst, size_t n);
int ei_encode_binary(char *buf, int *index, const void *p, long len)
{
char *s = buf + *index;
char *s0 = s;
if (!buf) s += 5;
else {
put8(s,ERL_BINARY_EXT);
put32be(s,len);
memmove(s,p,len);
}
s += len;
*index += s-s0;
return 0;
}
int ei_encode_bitstring(char *buf, int *index,
const char *p,
size_t bitoffs,
size_t bits)
{
char *s = buf + *index;
char *s0 = s;
size_t bytes = (bits + 7) / 8;
char last_bits = bits % 8;
if (!buf) s += last_bits ? 6 : 5;
else {
char* tagp = s++;
put32be(s, bytes);
if (last_bits) {
*tagp = ERL_BIT_BINARY_EXT;
put8(s, last_bits);
}
else
*tagp = ERL_BINARY_EXT;
copy_bits((const unsigned char*)p, bitoffs, (unsigned char*)s, bits);
}
s += bytes;
*index += s-s0;
return 0;
}
/*
* MAKE_MASK(n) constructs a mask with n bits.
* Example: MAKE_MASK(3) returns the binary number 00000111.
*/
#define MAKE_MASK(n) ((((unsigned) 1) << (n))-1)
static
void copy_bits(const unsigned char* src, /* Base pointer to source. */
size_t soffs, /* Bit offset for source relative to src. */
unsigned char* dst, /* Destination. */
size_t n) /* Number of bits to copy. */
{
unsigned rmask;
unsigned count;
unsigned deoffs;
unsigned bits;
unsigned bits1;
unsigned rshift;
if (n == 0)
return;
deoffs = n & 7;
rmask = deoffs ? (MAKE_MASK(deoffs) << (8-deoffs)) : 0;
if (soffs == 0) {
unsigned nbytes = (n + 7) / 8;
memcpy(dst, src, nbytes);
if (rmask)
dst[nbytes-1] &= rmask;
return;
}
src += soffs / 8;
soffs &= 7;
if (n < 8) { /* Less than one byte */
bits = (*src << soffs);
if (soffs+n > 8) {
src++;
bits |= (*src >> (8 - soffs));
}
*dst = bits & rmask;
return;
}
count = n >> 3;
rshift = 8 - soffs;
bits = *src;
if (soffs + n > 8) {
src++;
}
while (count--) {
bits1 = bits << soffs;
bits = *src;
src++;
*dst = bits1 | (bits >> rshift);
dst++;
}
if (rmask) {
bits1 = bits << soffs;
if ((rmask << rshift) & 0xff) {
bits = *src;
bits1 |= (bits >> rshift);
}
*dst = bits1 & rmask;
}
}
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