Move crc16 to helpers (#3780)

esphome/components/am2320/am2320.cpp

@@ -4,33 +4,15 @@
 //  - Arduino - AM2320: https://github.com/EngDial/AM2320/blob/master/src/AM2320.cpp
 
 #include "am2320.h"
-#include "esphome/core/log.h"
 #include "esphome/core/hal.h"
+#include "esphome/core/helpers.h"
+#include "esphome/core/log.h"
 
 namespace esphome {
 namespace am2320 {
 
 static const char *const TAG = "am2320";
 
-// ---=== Calc CRC16 ===---
-uint16_t crc_16(uint8_t *ptr, uint8_t length) {
-  uint16_t crc = 0xFFFF;
-  uint8_t i;
-  //------------------------------
-  while (length--) {
-    crc ^= *ptr++;
-    for (i = 0; i < 8; i++) {
-      if ((crc & 0x01) != 0) {
-        crc >>= 1;
-        crc ^= 0xA001;
-      } else {
-        crc >>= 1;
-      }
-    }
-  }
-  return crc;
-}
-
 void AM2320Component::update() {
   uint8_t data[8];
   data[0] = 0;
@@ -98,7 +80,7 @@ bool AM2320Component::read_data_(uint8_t *data) {
   checksum = data[7] << 8;
   checksum += data[6];
 
-  if (crc_16(data, 6) != checksum) {
+  if (crc16(data, 6) != checksum) {
     ESP_LOGW(TAG, "AM2320 Checksum invalid!");
     return false;
   }

esphome/components/modbus/modbus.cpp

@@ -35,22 +35,6 @@ void Modbus::loop() {
   }
 }
 
-uint16_t crc16(const uint8_t *data, uint8_t len) {
-  uint16_t crc = 0xFFFF;
-  while (len--) {
-    crc ^= *data++;
-    for (uint8_t i = 0; i < 8; i++) {
-      if ((crc & 0x01) != 0) {
-        crc >>= 1;
-        crc ^= 0xA001;
-      } else {
-        crc >>= 1;
-      }
-    }
-  }
-  return crc;
-}
-
 bool Modbus::parse_modbus_byte_(uint8_t byte) {
   size_t at = this->rx_buffer_.size();
   this->rx_buffer_.push_back(byte);

esphome/components/modbus/modbus.h

@@ -40,8 +40,6 @@ class Modbus : public uart::UARTDevice, public Component {
   std::vector<ModbusDevice *> devices_;
 };
 
-uint16_t crc16(const uint8_t *data, uint8_t len);
-
 class ModbusDevice {
  public:
   void set_parent(Modbus *parent) { parent_ = parent; }

esphome/components/senseair/senseair.cpp

@@ -1,4 +1,5 @@
 #include "senseair.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 namespace esphome {
@@ -42,7 +43,7 @@ void SenseAirComponent::update() {
     return;
   }
 
-  uint16_t calc_checksum = this->senseair_checksum_(response, 11);
+  uint16_t calc_checksum = crc16(response, 11);
   uint16_t resp_checksum = (uint16_t(response[12]) << 8) | response[11];
   if (resp_checksum != calc_checksum) {
     ESP_LOGW(TAG, "SenseAir checksum doesn't match: 0x%02X!=0x%02X", resp_checksum, calc_checksum);
@@ -60,23 +61,6 @@ void SenseAirComponent::update() {
     this->co2_sensor_->publish_state(ppm);
 }
 
-uint16_t SenseAirComponent::senseair_checksum_(uint8_t *ptr, uint8_t length) {
-  uint16_t crc = 0xFFFF;
-  uint8_t i;
-  while (length--) {
-    crc ^= *ptr++;
-    for (i = 0; i < 8; i++) {
-      if ((crc & 0x01) != 0) {
-        crc >>= 1;
-        crc ^= 0xA001;
-      } else {
-        crc >>= 1;
-      }
-    }
-  }
-  return crc;
-}
-
 void SenseAirComponent::background_calibration() {
   // Responses are just echoes but must be read to clear the buffer
   ESP_LOGD(TAG, "SenseAir Starting background calibration");

esphome/components/senseair/senseair.h

@@ -23,7 +23,6 @@ class SenseAirComponent : public PollingComponent, public uart::UARTDevice {
   void abc_disable();
 
  protected:
-  uint16_t senseair_checksum_(uint8_t *ptr, uint8_t length);
   bool senseair_write_command_(const uint8_t *command, uint8_t *response, uint8_t response_length);
 
   sensor::Sensor *co2_sensor_{nullptr};

esphome/core/helpers.cpp

@@ -62,6 +62,21 @@ uint8_t crc8(uint8_t *data, uint8_t len) {
   }
   return crc;
 }
+uint16_t crc16(const uint8_t *data, uint8_t len) {
+  uint16_t crc = 0xFFFF;
+  while (len--) {
+    crc ^= *data++;
+    for (uint8_t i = 0; i < 8; i++) {
+      if ((crc & 0x01) != 0) {
+        crc >>= 1;
+        crc ^= 0xA001;
+      } else {
+        crc >>= 1;
+      }
+    }
+  }
+  return crc;
+}
 uint32_t fnv1_hash(const std::string &str) {
   uint32_t hash = 2166136261UL;
   for (char c : str) {

esphome/core/helpers.h

@@ -149,6 +149,9 @@ template<typename T, typename U> T remap(U value, U min, U max, T min_out, T max
 /// Calculate a CRC-8 checksum of \p data with size \p len.
 uint8_t crc8(uint8_t *data, uint8_t len);
 
+/// Calculate a CRC-16 checksum of \p data with size \p len.
+uint16_t crc16(const uint8_t *data, uint8_t len);
+
 /// Calculate a FNV-1 hash of \p str.
 uint32_t fnv1_hash(const std::string &str);