[core] Add uint32_to_str helper and use in preferences (#15597)

tests/benchmarks/core/bench_helpers.cpp

@@ -1,4 +1,6 @@
 #include <benchmark/benchmark.h>
+#include <cinttypes>
+#include <cstdio>
 
 #include "esphome/core/helpers.h"
 
@@ -307,4 +309,58 @@ static void Base64Decode_32Bytes(benchmark::State &state) {
 }
 BENCHMARK(Base64Decode_32Bytes);
 
+// --- uint32_to_str() vs snprintf ---
+
+static void Uint32ToStr_Small(benchmark::State &state) {
+  char buf[UINT32_MAX_STR_SIZE];
+  for (auto _ : state) {
+    for (int i = 0; i < kInnerIterations; i++) {
+      uint32_to_str(buf, 12345);
+      benchmark::DoNotOptimize(buf);
+      benchmark::ClobberMemory();
+    }
+  }
+  state.SetItemsProcessed(state.iterations() * kInnerIterations);
+}
+BENCHMARK(Uint32ToStr_Small);
+
+static void Snprintf_Uint32_Small(benchmark::State &state) {
+  char buf[UINT32_MAX_STR_SIZE];
+  for (auto _ : state) {
+    for (int i = 0; i < kInnerIterations; i++) {
+      snprintf(buf, sizeof(buf), "%" PRIu32, static_cast<uint32_t>(12345));
+      benchmark::DoNotOptimize(buf);
+      benchmark::ClobberMemory();
+    }
+  }
+  state.SetItemsProcessed(state.iterations() * kInnerIterations);
+}
+BENCHMARK(Snprintf_Uint32_Small);
+
+static void Uint32ToStr_Large(benchmark::State &state) {
+  char buf[UINT32_MAX_STR_SIZE];
+  for (auto _ : state) {
+    for (int i = 0; i < kInnerIterations; i++) {
+      uint32_to_str(buf, 4294967295u);
+      benchmark::DoNotOptimize(buf);
+      benchmark::ClobberMemory();
+    }
+  }
+  state.SetItemsProcessed(state.iterations() * kInnerIterations);
+}
+BENCHMARK(Uint32ToStr_Large);
+
+static void Snprintf_Uint32_Large(benchmark::State &state) {
+  char buf[UINT32_MAX_STR_SIZE];
+  for (auto _ : state) {
+    for (int i = 0; i < kInnerIterations; i++) {
+      snprintf(buf, sizeof(buf), "%" PRIu32, static_cast<uint32_t>(4294967295u));
+      benchmark::DoNotOptimize(buf);
+      benchmark::ClobberMemory();
+    }
+  }
+  state.SetItemsProcessed(state.iterations() * kInnerIterations);
+}
+BENCHMARK(Snprintf_Uint32_Large);
+
 }  // namespace esphome::benchmarks

tests/components/core/test_uint32_to_str.cpp

@@ -0,0 +1,77 @@
+#include <gtest/gtest.h>
+
+#include "esphome/core/helpers.h"
+
+namespace esphome::core::testing {
+
+// --- uint32_to_str_unchecked() (internal, raw pointer) ---
+
+TEST(Uint32ToStr, InternalZero) {
+  char buf[UINT32_MAX_STR_SIZE];
+  char *end = uint32_to_str_unchecked(buf, 0);
+  *end = '\0';
+  EXPECT_STREQ(buf, "0");
+  EXPECT_EQ(end - buf, 1);
+}
+
+TEST(Uint32ToStr, InternalSingleDigit) {
+  char buf[UINT32_MAX_STR_SIZE];
+  char *end = uint32_to_str_unchecked(buf, 7);
+  *end = '\0';
+  EXPECT_STREQ(buf, "7");
+}
+
+TEST(Uint32ToStr, InternalMultiDigit) {
+  char buf[UINT32_MAX_STR_SIZE];
+  char *end = uint32_to_str_unchecked(buf, 12345);
+  *end = '\0';
+  EXPECT_STREQ(buf, "12345");
+  EXPECT_EQ(end - buf, 5);
+}
+
+TEST(Uint32ToStr, InternalMaxValue) {
+  char buf[UINT32_MAX_STR_SIZE];
+  char *end = uint32_to_str_unchecked(buf, 4294967295u);
+  *end = '\0';
+  EXPECT_STREQ(buf, "4294967295");
+  EXPECT_EQ(end - buf, 10);
+}
+
+TEST(Uint32ToStr, InternalPowersOfTen) {
+  char buf[UINT32_MAX_STR_SIZE];
+  char *end;
+
+  end = uint32_to_str_unchecked(buf, 10);
+  *end = '\0';
+  EXPECT_STREQ(buf, "10");
+
+  end = uint32_to_str_unchecked(buf, 100);
+  *end = '\0';
+  EXPECT_STREQ(buf, "100");
+
+  end = uint32_to_str_unchecked(buf, 1000000);
+  *end = '\0';
+  EXPECT_STREQ(buf, "1000000");
+}
+
+// --- uint32_to_str() (public, span API) ---
+
+TEST(Uint32ToStr, SpanZero) {
+  char buf[UINT32_MAX_STR_SIZE];
+  EXPECT_EQ(uint32_to_str(buf, 0), 1u);
+  EXPECT_STREQ(buf, "0");
+}
+
+TEST(Uint32ToStr, SpanMultiDigit) {
+  char buf[UINT32_MAX_STR_SIZE];
+  EXPECT_EQ(uint32_to_str(buf, 12345), 5u);
+  EXPECT_STREQ(buf, "12345");
+}
+
+TEST(Uint32ToStr, SpanMaxValue) {
+  char buf[UINT32_MAX_STR_SIZE];
+  EXPECT_EQ(uint32_to_str(buf, 4294967295u), 10u);
+  EXPECT_STREQ(buf, "4294967295");
+}
+
+}  // namespace esphome::core::testing