[rp2040] Use SmallBufferWithHeapFallback for preferences

esphome/components/rp2040/preferences.cpp

@@ -8,7 +8,6 @@
 #include "preferences.h"
 
 #include <cstring>
-#include <vector>
 
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
@@ -25,6 +24,9 @@ static bool s_flash_dirty = false;          // NOLINT(cppcoreguidelines-avoid-no
 
 static const uint32_t RP2040_FLASH_STORAGE_SIZE = 512;
 
+// Stack buffer size for preferences - covers virtually all real-world preferences without heap allocation
+static constexpr size_t PREF_BUFFER_SIZE = 64;
+
 extern "C" uint8_t _EEPROM_start;
 
 template<class It> uint8_t calculate_crc(It first, It last, uint32_t type) {
@@ -42,12 +44,14 @@ class RP2040PreferenceBackend : public ESPPreferenceBackend {
   uint32_t type = 0;
 
   bool save(const uint8_t *data, size_t len) override {
-    std::vector<uint8_t> buffer;
-    buffer.resize(len + 1);
-    memcpy(buffer.data(), data, len);
-    buffer[buffer.size() - 1] = calculate_crc(buffer.begin(), buffer.end() - 1, type);
+    const size_t buffer_size = len + 1;
+    SmallBufferWithHeapFallback<PREF_BUFFER_SIZE> buffer_alloc(buffer_size);
+    uint8_t *buffer = buffer_alloc.get();
 
-    for (uint32_t i = 0; i < len + 1; i++) {
+    memcpy(buffer, data, len);
+    buffer[len] = calculate_crc(buffer, buffer + len, type);
+
+    for (size_t i = 0; i < buffer_size; i++) {
       uint32_t j = offset + i;
       if (j >= RP2040_FLASH_STORAGE_SIZE)
         return false;
@@ -60,22 +64,23 @@ class RP2040PreferenceBackend : public ESPPreferenceBackend {
     return true;
   }
   bool load(uint8_t *data, size_t len) override {
-    std::vector<uint8_t> buffer;
-    buffer.resize(len + 1);
+    const size_t buffer_size = len + 1;
+    SmallBufferWithHeapFallback<PREF_BUFFER_SIZE> buffer_alloc(buffer_size);
+    uint8_t *buffer = buffer_alloc.get();
 
-    for (size_t i = 0; i < len + 1; i++) {
+    for (size_t i = 0; i < buffer_size; i++) {
       uint32_t j = offset + i;
       if (j >= RP2040_FLASH_STORAGE_SIZE)
         return false;
       buffer[i] = s_flash_storage[j];
     }
 
-    uint8_t crc = calculate_crc(buffer.begin(), buffer.end() - 1, type);
-    if (buffer[buffer.size() - 1] != crc) {
+    uint8_t crc = calculate_crc(buffer, buffer + len, type);
+    if (buffer[len] != crc) {
       return false;
     }
 
-    memcpy(data, buffer.data(), len);
+    memcpy(data, buffer, len);
     return true;
   }
 };

esphome/components/thermostat/thermostat_climate.cpp

@@ -1060,11 +1060,11 @@ bool ThermostatClimate::cooling_required_() {
   auto temperature = this->supports_two_points_ ? this->target_temperature_high : this->target_temperature;
 
   if (this->supports_cool_) {
-    if (this->current_temperature >= temperature + this->cooling_deadband_) {
-      // if the current temperature reaches or exceeds the target + deadband, cooling is required
+    if (this->current_temperature > temperature + this->cooling_deadband_) {
+      // if the current temperature exceeds the target + deadband, cooling is required
       return true;
-    } else if (this->current_temperature <= temperature - this->cooling_overrun_) {
-      // if the current temperature is less than or equal to the target - overrun, cooling should stop
+    } else if (this->current_temperature < temperature - this->cooling_overrun_) {
+      // if the current temperature is less than the target - overrun, cooling should stop
       return false;
     } else {
       // if we get here, the current temperature is between target + deadband and target - overrun,
@@ -1081,11 +1081,11 @@ bool ThermostatClimate::fanning_required_() {
 
   if (this->supports_fan_only_) {
     if (this->supports_fan_only_cooling_) {
-      if (this->current_temperature >= temperature + this->cooling_deadband_) {
-        // if the current temperature reaches or exceeds the target + deadband, fanning is required
+      if (this->current_temperature > temperature + this->cooling_deadband_) {
+        // if the current temperature exceeds the target + deadband, fanning is required
         return true;
-      } else if (this->current_temperature <= temperature - this->cooling_overrun_) {
-        // if the current temperature is less than or equal to the target - overrun, fanning should stop
+      } else if (this->current_temperature < temperature - this->cooling_overrun_) {
+        // if the current temperature is less than the target - overrun, fanning should stop
         return false;
       } else {
         // if we get here, the current temperature is between target + deadband and target - overrun,
@@ -1103,12 +1103,11 @@ bool ThermostatClimate::heating_required_() {
   auto temperature = this->supports_two_points_ ? this->target_temperature_low : this->target_temperature;
 
   if (this->supports_heat_) {
-    if (this->current_temperature <= temperature - this->heating_deadband_) {
-      // if the current temperature is below or equal to the target - deadband, heating is required
+    if (this->current_temperature < temperature - this->heating_deadband_) {
+      // if the current temperature is below the target - deadband, heating is required
       return true;
-    } else if (this->current_temperature >= temperature + this->heating_overrun_) {
-      // if the current temperature is above or equal to the target + overrun, heating should stop
-
+    } else if (this->current_temperature > temperature + this->heating_overrun_) {
+      // if the current temperature is above the target + overrun, heating should stop
       return false;
     } else {
       // if we get here, the current temperature is between target - deadband and target + overrun,