osd-contiki/apps/oma-lwm2m/oma-tlv.c

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/*
* Copyright (c) 2015, Yanzi Networks AB.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \addtogroup oma-lwm2m
* @{
*
*/
/**
* \file
* Implementation of the Contiki OMA LWM2M TLV
* \author
* Joakim Eriksson <joakime@sics.se>
* Niclas Finne <nfi@sics.se>
*/
#include <string.h>
#include <stdint.h>
#include "oma-tlv.h"
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
static inline uint8_t
get_len_type(const oma_tlv_t *tlv)
{
if(tlv->length < 8) {
return 0;
} else if(tlv->length < 256) {
return 1;
} else if(tlv->length < 0x10000) {
return 2;
} else {
return 3;
}
}
/*---------------------------------------------------------------------------*/
size_t
oma_tlv_read(oma_tlv_t *tlv, const uint8_t *buffer, size_t len)
{
uint8_t len_type;
uint8_t len_pos = 1;
size_t tlv_len;
tlv->type = (buffer[0] >> 6) & 3;
len_type = (buffer[0] >> 3) & 3;
len_pos = 1 + (((buffer[0] & (1 << 5)) != 0) ? 2 : 1);
tlv->id = buffer[1];
/* if len_pos is larger than two it means that there is more ID to read */
if(len_pos > 2) {
tlv->id = (tlv->id << 8) + buffer[2];
}
if(len_type == 0) {
tlv_len = buffer[0] & 7;
} else {
/* read the length */
tlv_len = 0;
while(len_type > 0) {
tlv_len = tlv_len << 8 | buffer[len_pos++];
len_type--;
}
}
/* and read out the data??? */
tlv->length = tlv_len;
tlv->value = &buffer[len_pos];
return len_pos + tlv_len;
}
/*---------------------------------------------------------------------------*/
size_t
oma_tlv_get_size(const oma_tlv_t *tlv)
{
size_t size;
/* first hdr + len size */
size = 1 + get_len_type(tlv);
/* id size */
size += (tlv->id > 255) ? 2 : 1;
/* and the length */
size += tlv->length;
return size;
}
/*---------------------------------------------------------------------------*/
size_t
oma_tlv_write(const oma_tlv_t *tlv, uint8_t *buffer, size_t len)
{
int pos;
uint8_t len_type;
/* len type is the same as number of bytes required for length */
len_type = get_len_type(tlv);
pos = 1 + len_type;
/* ensure that we do not write too much */
if(len < tlv->length + pos) {
PRINTF("OMA-TLV: Could not write the TLV - buffer overflow.\n");
return 0;
}
/* first type byte in TLV header */
buffer[0] = (tlv->type << 6) |
(tlv->id > 255 ? (1 << 5) : 0) |
(len_type << 3) |
(len_type == 0 ? tlv->length : 0);
pos = 1;
/* The ID */
if(tlv->id > 255) {
buffer[pos++] = (tlv->id >> 8) & 0xff;
}
buffer[pos++] = tlv->id & 0xff;
/* Add length if needed - unrolled loop ? */
if(len_type > 2) {
buffer[pos++] = (tlv->length >> 16) & 0xff;
}
if(len_type > 1) {
buffer[pos++] = (tlv->length >> 8) & 0xff;
}
if(len_type > 0) {
buffer[pos++] = tlv->length & 0xff;
}
/* finally add the value */
memcpy(&buffer[pos], tlv->value, tlv->length);
if(DEBUG) {
int i;
PRINTF("TLV:");
for(i = 0; i < pos + tlv->length; i++) {
PRINTF("%02x", buffer[i]);
}
PRINTF("\n");
}
return pos + tlv->length;
}
/*---------------------------------------------------------------------------*/
int32_t
oma_tlv_get_int32(const oma_tlv_t *tlv)
{
int i;
int32_t value = 0;
/* will probably need to handle MSB as a sign bit? */
for(i = 0; i < tlv->length; i++) {
value = (value << 8) | tlv->value[i];
}
return value;
}
/*---------------------------------------------------------------------------*/
size_t
oma_tlv_write_int32(int16_t id, int32_t value, uint8_t *buffer, size_t len)
{
oma_tlv_t tlv;
size_t tlvlen = 0;
uint8_t buf[4];
int i;
PRINTF("Exporting int32 %d %ld ", id, (long)value);
buf[3] = value & 0xff;
value = value >> 8;
for(i = 1; value > 0 && i < 4; i++) {
buf[3 - i] = value & 0xff;
value = value >> 8;
}
tlvlen = i;
/* export INT as TLV */
PRINTF("len: %zu\n", tlvlen);
tlv.type = OMA_TLV_TYPE_RESOURCE;
tlv.length = tlvlen;
tlv.value = &buf[3 - (tlvlen - 1)];
tlv.id = id;
return oma_tlv_write(&tlv, buffer, len);
}
/*---------------------------------------------------------------------------*/
/* convert fixpoint 32-bit to a IEEE Float in the byte array*/
size_t
oma_tlv_write_float32(int16_t id, int32_t value, int bits,
uint8_t *buffer, size_t len)
{
int i;
int e = 0;
int32_t val = 0;
int32_t v;
uint8_t b[4];
oma_tlv_t tlv;
v = value;
if(v < 0) {
v = -v;
}
while(v > 1) {
val = (val >> 1);
if (v & 1) {
val = val | (1L << 22);
}
v = (v >> 1);
e++;
}
PRINTF("Sign: %d, Fraction: %06lx 0b", value < 0, (long)val);
for(i = 0; i < 23; i++) {
PRINTF("%d", (int)((val >> (22 - i)) & 1));
}
PRINTF("\nExp:%d\n", e);
/* convert to the thing we should have */
e = e - bits + 127;
/* is this the right byte order? */
b[0] = (value < 0 ? 0x80 : 0) | (e >> 1);
b[1] = ((e & 1) << 7) | ((val >> 16) & 0x7f);
b[2] = (val >> 8) & 0xff;
b[3] = val & 0xff;
/* construct the TLV */
tlv.type = OMA_TLV_TYPE_RESOURCE;
tlv.length = 4;
tlv.value = b;
tlv.id = id;
return oma_tlv_write(&tlv, buffer, len);
}
/*---------------------------------------------------------------------------*/
/* convert float to fixpoint */
size_t
oma_tlv_float32_to_fix(const oma_tlv_t *tlv, int32_t *value, int bits)
{
/* TLV needs to be 4 bytes */
int e, i;
int32_t val;
int sign = (tlv->value[0] & 0x80) != 0;
e = ((tlv->value[0] << 1) & 0xff) | (tlv->value[1] >> 7);
val = (((long)tlv->value[1] & 0x7f) << 16) | (tlv->value[2] << 8) | tlv->value[3];
PRINTF("Sign: %d, Fraction: %06lx 0b", val < 0, (long)val);
for(i = 0; i < 23; i++) {
PRINTF("%d", (int)((val >> (22 - i)) & 1));
}
PRINTF("\nExp:%d => %d\n", e, e - 127);
e = e - 127 + bits;
/* e corresponds to the number of times we need to roll the number */
PRINTF("Actual e=%d\n", e);
e = e - 23;
PRINTF("E after sub %d\n", e);
val = val | 1L << 23;
if(e > 0) {
val = val << e;
} else {
val = val >> -e;
}
*value = sign ? -val : val;
return 4;
}
/*---------------------------------------------------------------------------*/
/** @} */