From 7acde0ab60cacf8199e1a05b75539d291b548215 Mon Sep 17 00:00:00 2001 From: "J. Nick Koston" Date: Sun, 18 Jan 2026 13:45:49 -1000 Subject: [PATCH] [debug] ESP8266: Eliminate heap allocations from Arduino String functions --- esphome/components/debug/debug_esp8266.cpp | 104 ++++++++++++++++----- 1 file changed, 82 insertions(+), 22 deletions(-) diff --git a/esphome/components/debug/debug_esp8266.cpp b/esphome/components/debug/debug_esp8266.cpp index 274f77e20d..f441906f5d 100644 --- a/esphome/components/debug/debug_esp8266.cpp +++ b/esphome/components/debug/debug_esp8266.cpp @@ -3,21 +3,81 @@ #include "esphome/core/log.h" #include +extern "C" { +#include + +// Global reset info struct populated by SDK at boot +extern struct rst_info resetInfo; + +// Core version - either a string pointer or a version number to format as hex +extern uint32_t core_version; +extern const char *core_release; +} + namespace esphome { namespace debug { static const char *const TAG = "debug"; +// Get reset reason string from reason code (no heap allocation) +// Returns LogString* pointing to flash (PROGMEM) on ESP8266 +static const LogString *get_reset_reason_str(uint32_t reason) { + switch (reason) { + case REASON_DEFAULT_RST: + return LOG_STR("Power On"); + case REASON_WDT_RST: + return LOG_STR("Hardware Watchdog"); + case REASON_EXCEPTION_RST: + return LOG_STR("Exception"); + case REASON_SOFT_WDT_RST: + return LOG_STR("Software Watchdog"); + case REASON_SOFT_RESTART: + return LOG_STR("Software/System restart"); + case REASON_DEEP_SLEEP_AWAKE: + return LOG_STR("Deep-Sleep Wake"); + case REASON_EXT_SYS_RST: + return LOG_STR("External System"); + default: + return LOG_STR("Unknown"); + } +} + +// Buffer for core version hex string (static to avoid stack/heap allocation each call) +static char core_version_hex_[12]; + +// Get core version string (no heap allocation) +// Returns either core_release directly or formats core_version as hex +static const char *get_core_version_str() { + if (core_release != nullptr) { + return core_release; + } + snprintf_P(core_version_hex_, sizeof(core_version_hex_), PSTR("%08x"), core_version); + return core_version_hex_; +} + +// Buffer for reset info string (static to avoid stack/heap allocation each call) +static char reset_info_buf_[200]; + +// Get detailed reset info string (no heap allocation) +// For watchdog/exception resets, includes detailed exception info +// Returns LogString* for simple cases, or pointer to static buffer for detailed info +static const char *get_reset_info_str() { + if (resetInfo.reason >= REASON_WDT_RST && resetInfo.reason <= REASON_SOFT_WDT_RST) { + snprintf_P(reset_info_buf_, sizeof(reset_info_buf_), + PSTR("Fatal exception:%d flag:%d (%s) epc1:0x%08x epc2:0x%08x epc3:0x%08x excvaddr:0x%08x depc:0x%08x"), + static_cast(resetInfo.exccause), static_cast(resetInfo.reason), + LOG_STR_ARG(get_reset_reason_str(resetInfo.reason)), resetInfo.epc1, resetInfo.epc2, resetInfo.epc3, + resetInfo.excvaddr, resetInfo.depc); + return reset_info_buf_; + } + return LOG_STR_ARG(get_reset_reason_str(resetInfo.reason)); +} + const char *DebugComponent::get_reset_reason_(std::span buffer) { - char *buf = buffer.data(); -#if !defined(CLANG_TIDY) - String reason = ESP.getResetReason(); // NOLINT - snprintf_P(buf, RESET_REASON_BUFFER_SIZE, PSTR("%s"), reason.c_str()); - return buf; -#else - buf[0] = '\0'; - return buf; -#endif + // Copy from flash to provided buffer + strncpy_P(buffer.data(), (PGM_P) get_reset_reason_str(resetInfo.reason), RESET_REASON_BUFFER_SIZE - 1); + buffer.data()[RESET_REASON_BUFFER_SIZE - 1] = '\0'; + return buffer.data(); } const char *DebugComponent::get_wakeup_cause_(std::span buffer) { @@ -53,8 +113,8 @@ size_t DebugComponent::get_device_info_(std::span uint32_t flash_size = ESP.getFlashChipSize() / 1024; // NOLINT uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000; // NOLINT ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed, flash_mode); - pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed, - flash_mode); + pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed, + flash_mode); #if !defined(CLANG_TIDY) char reason_buffer[RESET_REASON_BUFFER_SIZE]; @@ -74,18 +134,18 @@ size_t DebugComponent::get_device_info_(std::span "Flash Chip ID=0x%08" PRIX32 "\n" "Reset Reason: %s\n" "Reset Info: %s", - chip_id, ESP.getSdkVersion(), ESP.getCoreVersion().c_str(), boot_version, boot_mode, cpu_freq, flash_chip_id, - reset_reason, ESP.getResetInfo().c_str()); + chip_id, ESP.getSdkVersion(), get_core_version_str(), boot_version, boot_mode, cpu_freq, flash_chip_id, + reset_reason, get_reset_info_str()); - pos = buf_append(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id); - pos = buf_append(buf, size, pos, "|SDK: %s", ESP.getSdkVersion()); - pos = buf_append(buf, size, pos, "|Core: %s", ESP.getCoreVersion().c_str()); - pos = buf_append(buf, size, pos, "|Boot: %u", boot_version); - pos = buf_append(buf, size, pos, "|Mode: %u", boot_mode); - pos = buf_append(buf, size, pos, "|CPU: %u", cpu_freq); - pos = buf_append(buf, size, pos, "|Flash: 0x%08" PRIX32, flash_chip_id); - pos = buf_append(buf, size, pos, "|Reset: %s", reset_reason); - pos = buf_append(buf, size, pos, "|%s", ESP.getResetInfo().c_str()); + pos = buf_append_printf(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id); + pos = buf_append_printf(buf, size, pos, "|SDK: %s", ESP.getSdkVersion()); + pos = buf_append_printf(buf, size, pos, "|Core: %s", get_core_version_str()); + pos = buf_append_printf(buf, size, pos, "|Boot: %u", boot_version); + pos = buf_append_printf(buf, size, pos, "|Mode: %u", boot_mode); + pos = buf_append_printf(buf, size, pos, "|CPU: %u", cpu_freq); + pos = buf_append_printf(buf, size, pos, "|Flash: 0x%08" PRIX32, flash_chip_id); + pos = buf_append_printf(buf, size, pos, "|Reset: %s", reset_reason); + pos = buf_append_printf(buf, size, pos, "|%s", get_reset_info_str()); #endif return pos;