[esp32_ble] Optimize BLE hex formatting to eliminate sprintf dependency (#10714)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

esphome/components/bluetooth_proxy/bluetooth_proxy.h

@@ -130,7 +130,9 @@ class BluetoothProxy final : public esp32_ble_tracker::ESPBTDeviceListener, publ
 
   std::string get_bluetooth_mac_address_pretty() {
     const uint8_t *mac = esp_bt_dev_get_address();
-    return str_snprintf("%02X:%02X:%02X:%02X:%02X:%02X", 17, mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+    char buf[18];
+    format_mac_addr_upper(mac, buf);
+    return std::string(buf);
   }
 
  protected:

esphome/components/esp32_ble/ble_uuid.cpp

@@ -7,6 +7,7 @@
 #include <cstdio>
 #include <cinttypes>
 #include "esphome/core/log.h"
+#include "esphome/core/helpers.h"
 
 namespace esphome::esp32_ble {
 
@@ -169,22 +170,42 @@ bool ESPBTUUID::operator==(const ESPBTUUID &uuid) const {
 }
 esp_bt_uuid_t ESPBTUUID::get_uuid() const { return this->uuid_; }
 std::string ESPBTUUID::to_string() const {
+  char buf[40];  // Enough for 128-bit UUID with dashes
+  char *pos = buf;
+
   switch (this->uuid_.len) {
     case ESP_UUID_LEN_16:
-      return str_snprintf("0x%02X%02X", 6, this->uuid_.uuid.uuid16 >> 8, this->uuid_.uuid.uuid16 & 0xff);
+      *pos++ = '0';
+      *pos++ = 'x';
+      *pos++ = format_hex_pretty_char(this->uuid_.uuid.uuid16 >> 12);
+      *pos++ = format_hex_pretty_char((this->uuid_.uuid.uuid16 >> 8) & 0x0F);
+      *pos++ = format_hex_pretty_char((this->uuid_.uuid.uuid16 >> 4) & 0x0F);
+      *pos++ = format_hex_pretty_char(this->uuid_.uuid.uuid16 & 0x0F);
+      *pos = '\0';
+      return std::string(buf);
+
     case ESP_UUID_LEN_32:
-      return str_snprintf("0x%02" PRIX32 "%02" PRIX32 "%02" PRIX32 "%02" PRIX32, 10, (this->uuid_.uuid.uuid32 >> 24),
-                          (this->uuid_.uuid.uuid32 >> 16 & 0xff), (this->uuid_.uuid.uuid32 >> 8 & 0xff),
-                          this->uuid_.uuid.uuid32 & 0xff);
+      *pos++ = '0';
+      *pos++ = 'x';
+      for (int shift = 28; shift >= 0; shift -= 4) {
+        *pos++ = format_hex_pretty_char((this->uuid_.uuid.uuid32 >> shift) & 0x0F);
+      }
+      *pos = '\0';
+      return std::string(buf);
+
     default:
     case ESP_UUID_LEN_128:
-      std::string buf;
+      // Format: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
       for (int8_t i = 15; i >= 0; i--) {
-        buf += str_snprintf("%02X", 2, this->uuid_.uuid.uuid128[i]);
-        if (i == 6 || i == 8 || i == 10 || i == 12)
-          buf += "-";
+        uint8_t byte = this->uuid_.uuid.uuid128[i];
+        *pos++ = format_hex_pretty_char(byte >> 4);
+        *pos++ = format_hex_pretty_char(byte & 0x0F);
+        if (i == 12 || i == 10 || i == 8 || i == 6) {
+          *pos++ = '-';
+        }
       }
-      return buf;
+      *pos = '\0';
+      return std::string(buf);
   }
   return "";
 }

esphome/components/esp32_ble_beacon/esp32_ble_beacon.cpp

@@ -31,12 +31,13 @@ void ESP32BLEBeacon::dump_config() {
   char uuid[37];
   char *bpos = uuid;
   for (int8_t ii = 0; ii < 16; ++ii) {
-    bpos += sprintf(bpos, "%02X", this->uuid_[ii]);
+    *bpos++ = format_hex_pretty_char(this->uuid_[ii] >> 4);
+    *bpos++ = format_hex_pretty_char(this->uuid_[ii] & 0x0F);
     if (ii == 3 || ii == 5 || ii == 7 || ii == 9) {
-      bpos += sprintf(bpos, "-");
+      *bpos++ = '-';
     }
   }
-  uuid[36] = '\0';
+  *bpos = '\0';
   ESP_LOGCONFIG(TAG,
                 "  UUID: %s, Major: %u, Minor: %u, Min Interval: %ums, Max Interval: %ums, Measured Power: %d"
                 ", TX Power: %ddBm",

esphome/components/esp32_ble_client/ble_client_base.h

@@ -60,11 +60,14 @@ class BLEClientBase : public espbt::ESPBTClient, public Component {
     if (address == 0) {
       this->address_str_ = "";
     } else {
-      this->address_str_ =
-          str_snprintf("%02X:%02X:%02X:%02X:%02X:%02X", 17, (uint8_t) (this->address_ >> 40) & 0xff,
-                       (uint8_t) (this->address_ >> 32) & 0xff, (uint8_t) (this->address_ >> 24) & 0xff,
-                       (uint8_t) (this->address_ >> 16) & 0xff, (uint8_t) (this->address_ >> 8) & 0xff,
-                       (uint8_t) (this->address_ >> 0) & 0xff);
+      char buf[18];
+      uint8_t mac[6] = {
+          (uint8_t) ((this->address_ >> 40) & 0xff), (uint8_t) ((this->address_ >> 32) & 0xff),
+          (uint8_t) ((this->address_ >> 24) & 0xff), (uint8_t) ((this->address_ >> 16) & 0xff),
+          (uint8_t) ((this->address_ >> 8) & 0xff),  (uint8_t) ((this->address_ >> 0) & 0xff),
+      };
+      format_mac_addr_upper(mac, buf);
+      this->address_str_ = buf;
     }
   }
   const std::string &address_str() const { return this->address_str_; }

esphome/components/esp32_ble_tracker/esp32_ble_tracker.cpp

@@ -607,9 +607,8 @@ void ESPBTDevice::parse_adv_(const uint8_t *payload, uint8_t len) {
 }
 
 std::string ESPBTDevice::address_str() const {
-  char mac[24];
-  snprintf(mac, sizeof(mac), "%02X:%02X:%02X:%02X:%02X:%02X", this->address_[0], this->address_[1], this->address_[2],
-           this->address_[3], this->address_[4], this->address_[5]);
+  char mac[18];
+  format_mac_addr_upper(this->address_, mac);
   return mac;
 }