serial log on webserver

main/serial_log.h

@@ -0,0 +1,47 @@
+/*
+ * MTG RFID Companion - In-memory Serial Log Ring Buffer
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Initialize the serial log ring buffer and hook into esp_log_set_vprintf.
+ *
+ * Hardware UART serial output remains active and unaffected.
+ */
+esp_err_t serial_log_init(void);
+
+/**
+ * @brief Read logs starting from a specific byte offset.
+ *
+ * @param from_offset Monotonically increasing byte sequence offset previously read.
+ *                    If 0 or if the offset has fallen outside the ring buffer window,
+ *                    the available recent buffer content is returned.
+ * @param dest Output buffer to receive log bytes.
+ * @param max_len Maximum bytes to write into dest.
+ * @param next_offset Pointer to store the new byte offset cursor.
+ * @return Number of bytes copied into dest.
+ */
+size_t serial_log_read(uint32_t from_offset, char *dest, size_t max_len, uint32_t *next_offset);
+
+/**
+ * @brief Clear the serial log buffer.
+ */
+void serial_log_clear(void);
+
+/**
+ * @brief Get total lifetime log bytes written.
+ */
+uint32_t serial_log_get_total_bytes(void);
+
+#ifdef __cplusplus
+}
+#endif