vesc_utility.cpp

Go to the documentation of this file.

/* 
 * This file is part of the arduino vesc library (https://github.com/arduino_vesc)
 * 
 * Copyright (c) 2019 Gianmarco Vitelli
 * 
 * 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, version 3.
 *
 * 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 
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License 
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
#include <Arduino.h>
#include <math.h>
#include <stdbool.h>
#include "vesc_utility.h"
 
void VescUtility::utility_append_int16(uint8_t* buffer, int16_t number, int32_t *index) {
  buffer[(*index)++] = number >> 8;
  buffer[(*index)++] = number;
}
 
void VescUtility::utility_append_uint16(uint8_t* buffer, uint16_t number, int32_t *index) {
  buffer[(*index)++] = number >> 8;
  buffer[(*index)++] = number;
}
 
void VescUtility::utility_append_int32(uint8_t* buffer, int32_t number, int32_t *index) {
  buffer[(*index)++] = number >> 24;
  buffer[(*index)++] = number >> 16;
  buffer[(*index)++] = number >> 8;
  buffer[(*index)++] = number;
}
 
void VescUtility::utility_append_uint32(uint8_t* buffer, uint32_t number, int32_t *index) {
  buffer[(*index)++] = number >> 24;
  buffer[(*index)++] = number >> 16;
  buffer[(*index)++] = number >> 8;
  buffer[(*index)++] = number;
}
 
void VescUtility::utility_append_float16(uint8_t* buffer, float number, float scale, int32_t *index) {
    VescUtility::utility_append_int16(buffer, (int16_t)(number * scale), index);
}
 
void VescUtility::utility_append_float32(uint8_t* buffer, float number, float scale, int32_t *index) {
    VescUtility::utility_append_int32(buffer, (int32_t)(number * scale), index);
}
 
void VescUtility::utility_append_float32_auto(uint8_t* buffer, float number, int32_t *index) {
  int e = 0;
  float sig = frexpf(number, &e);
  float sig_abs = fabsf(sig);
  uint32_t sig_i = 0;
 
  if (sig_abs >= 0.5) {
    sig_i = (uint32_t)((sig_abs - 0.5f) * 2.0f * 8388608.0f);
    e += 126;
  }
 
  uint32_t res = ((e & 0xFF) << 23) | (sig_i & 0x7FFFFF);
  if (sig < 0) {
    res |= 1U << 31;
  }
 
  VescUtility::utility_append_uint32(buffer, res, index);
}
 
int16_t VescUtility::utility_get_int16(const uint8_t *buffer, int32_t *index) {
  int16_t res = ((uint16_t) buffer[*index]) << 8 |
          ((uint16_t) buffer[*index + 1]);
  *index += 2;
  return res;
}
 
uint16_t VescUtility::utility_get_uint16(const uint8_t *buffer, int32_t *index) {
  uint16_t res =  ((uint16_t) buffer[*index]) << 8 |
          ((uint16_t) buffer[*index + 1]);
  *index += 2;
  return res;
}
 
int32_t VescUtility::utility_get_int32(const uint8_t *buffer, int32_t *index) {
  int32_t res = ((uint32_t) buffer[*index]) << 24 |
          ((uint32_t) buffer[*index + 1]) << 16 |
          ((uint32_t) buffer[*index + 2]) << 8 |
          ((uint32_t) buffer[*index + 3]);
  *index += 4;
  return res;
}
 
uint32_t VescUtility::utility_get_uint32(const uint8_t *buffer, int32_t *index) {
  uint32_t res =  ((uint32_t) buffer[*index]) << 24 |
          ((uint32_t) buffer[*index + 1]) << 16 |
          ((uint32_t) buffer[*index + 2]) << 8 |
          ((uint32_t) buffer[*index + 3]);
  *index += 4;
  return res;
}
 
float VescUtility::utility_get_float16(const uint8_t *buffer, float scale, int32_t *index) {
    return VescUtility::utility_get_int16(buffer, index) / scale;
}
 
float VescUtility::utility_get_float32(const uint8_t *buffer, float scale, int32_t *index) {
    return VescUtility::utility_get_int32(buffer, index) / scale;
}
 
float VescUtility::utility_get_float32_auto(const uint8_t *buffer, int32_t *index) {
  uint32_t res = VescUtility::utility_get_uint32(buffer, index);
 
  int e = (res >> 23) & 0xFF;
  uint32_t sig_i = res & 0x7FFFFF;
  bool neg = res & (1U << 31);
 
  float sig = 0.0;
  if (e != 0 || sig_i != 0) {
    sig = (float)sig_i / (8388608.0 * 2.0) + 0.5;
    e -= 126;
  }
 
  if (neg) {
    sig = -sig;
  }
 
  return ldexpf(sig, e);
}