modbus-data.c
2.52 KB
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/*
* Copyright © 2010 Stéphane Raimbault <stephane.raimbault@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser Public License for more details.
*
* You should have received a copy of the GNU Lesser Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#ifndef _MSC_VER
#include <stdint.h>
#else
#include "stdint.h"
#endif
#include <string.h>
#include <assert.h>
#include <netinet/in.h>
/* Sets many bits from a single byte value (all 8 bits of the byte value are
set) */
void modbus_set_bits_from_byte(uint8_t *dest, int address, const uint8_t value)
{
int i;
for (i=0; i<8; i++) {
dest[address+i] = (value & (1 << i)) ? 1 : 0;
}
}
/* Sets many bits from a table of bytes (only the bits between address and
address + nb_bits are set) */
void modbus_set_bits_from_bytes(uint8_t *dest, int address, unsigned int nb_bits,
const uint8_t *tab_byte)
{
int i;
int shift = 0;
for (i = address; i < address + nb_bits; i++) {
dest[i] = tab_byte[(i - address) / 8] & (1 << shift) ? 1 : 0;
/* gcc doesn't like: shift = (++shift) % 8; */
shift++;
shift %= 8;
}
}
/* Gets the byte value from many bits.
To obtain a full byte, set nb_bits to 8. */
uint8_t modbus_get_byte_from_bits(const uint8_t *src, int address,
unsigned int nb_bits)
{
int i;
uint8_t value = 0;
if (nb_bits > 8) {
/* Assert is ignored if NDEBUG is set */
assert(nb_bits < 8);
nb_bits = 8;
}
for (i=0; i < nb_bits; i++) {
value |= (src[address+i] << i);
}
return value;
}
/* Get a float from 4 bytes in Modbus format */
float modbus_get_float(const uint16_t *src)
{
float f = 0.0f;
uint32_t i;
i = (((uint32_t)src[1]) << 16) + src[0];
memcpy(&f, &i, sizeof(float));
return f;
}
/* Set a float to 4 bytes in Modbus format */
void modbus_set_float(float f, uint16_t *dest)
{
uint32_t i = 0;
memcpy(&i, &f, sizeof(uint32_t));
dest[0] = (uint16_t)i;
dest[1] = (uint16_t)(i >> 16);
}