serial log on webserver

main/serial_log.c

@@ -0,0 +1,152 @@
+/*
+ * MTG RFID Companion - In-memory Serial Log Ring Buffer
+ */
+
+#include "serial_log.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include "esp_log.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+
+#define LOG_BUFFER_SIZE (16 * 1024)
+
+static vprintf_like_t s_prev_vprintf = NULL;
+static char s_ring_buffer[LOG_BUFFER_SIZE];
+static uint32_t s_write_idx = 0;
+static uint32_t s_total_bytes = 0;
+static portMUX_TYPE s_log_mux = portMUX_INITIALIZER_UNLOCKED;
+
+static int serial_log_vprintf(const char *fmt, va_list args)
+{
+    int ret = 0;
+
+    /* Maintain original console/UART output */
+    if (s_prev_vprintf != NULL) {
+        va_list copy1;
+        va_copy(copy1, args);
+        ret = s_prev_vprintf(fmt, copy1);
+        va_end(copy1);
+    } else {
+        va_list copy1;
+        va_copy(copy1, args);
+        ret = vprintf(fmt, copy1);
+        va_end(copy1);
+    }
+
+    /* Format message into local buffer */
+    char line_buf[512];
+    va_list copy2;
+    va_copy(copy2, args);
+    int written = vsnprintf(line_buf, sizeof(line_buf), fmt, copy2);
+    va_end(copy2);
+
+    if (written > 0) {
+        size_t len = (size_t)written;
+        if (len >= sizeof(line_buf)) {
+            len = sizeof(line_buf) - 1;
+        }
+
+        portENTER_CRITICAL(&s_log_mux);
+        size_t space_to_end = LOG_BUFFER_SIZE - s_write_idx;
+        if (len <= space_to_end) {
+            memcpy(&s_ring_buffer[s_write_idx], line_buf, len);
+            s_write_idx = (s_write_idx + len) % LOG_BUFFER_SIZE;
+        } else {
+            memcpy(&s_ring_buffer[s_write_idx], line_buf, space_to_end);
+            memcpy(&s_ring_buffer[0], line_buf + space_to_end, len - space_to_end);
+            s_write_idx = (uint32_t)(len - space_to_end);
+        }
+        s_total_bytes += (uint32_t)len;
+        portEXIT_CRITICAL(&s_log_mux);
+    }
+
+    return ret;
+}
+
+esp_err_t serial_log_init(void)
+{
+    portENTER_CRITICAL(&s_log_mux);
+    s_total_bytes = 0;
+    s_write_idx = 0;
+    memset(s_ring_buffer, 0, sizeof(s_ring_buffer));
+    portEXIT_CRITICAL(&s_log_mux);
+
+    s_prev_vprintf = esp_log_set_vprintf(serial_log_vprintf);
+    return ESP_OK;
+}
+
+size_t serial_log_read(uint32_t from_offset, char *dest, size_t max_len, uint32_t *next_offset)
+{
+    if (!dest || max_len == 0) {
+        if (next_offset) {
+            *next_offset = from_offset;
+        }
+        return 0;
+    }
+
+    size_t copied = 0;
+
+    portENTER_CRITICAL(&s_log_mux);
+
+    uint32_t total = s_total_bytes;
+    uint32_t oldest = (total > LOG_BUFFER_SIZE) ? (total - LOG_BUFFER_SIZE) : 0;
+
+    if (from_offset < oldest || from_offset == 0) {
+        from_offset = oldest;
+    }
+
+    if (from_offset >= total) {
+        if (next_offset) {
+            *next_offset = total;
+        }
+        dest[0] = '\0';
+        portEXIT_CRITICAL(&s_log_mux);
+        return 0;
+    }
+
+    uint32_t to_read = total - from_offset;
+    if (to_read > (uint32_t)(max_len - 1)) {
+        to_read = (uint32_t)(max_len - 1);
+    }
+
+    size_t start_idx = from_offset % LOG_BUFFER_SIZE;
+    size_t chunk1 = LOG_BUFFER_SIZE - start_idx;
+
+    if (to_read <= chunk1) {
+        memcpy(dest, &s_ring_buffer[start_idx], to_read);
+    } else {
+        memcpy(dest, &s_ring_buffer[start_idx], chunk1);
+        memcpy(dest + chunk1, &s_ring_buffer[0], to_read - chunk1);
+    }
+
+    copied = to_read;
+    dest[copied] = '\0';
+
+    if (next_offset) {
+        *next_offset = from_offset + (uint32_t)to_read;
+    }
+
+    portEXIT_CRITICAL(&s_log_mux);
+
+    return copied;
+}
+
+void serial_log_clear(void)
+{
+    portENTER_CRITICAL(&s_log_mux);
+    s_total_bytes = 0;
+    s_write_idx = 0;
+    memset(s_ring_buffer, 0, sizeof(s_ring_buffer));
+    portEXIT_CRITICAL(&s_log_mux);
+}
+
+uint32_t serial_log_get_total_bytes(void)
+{
+    uint32_t total;
+    portENTER_CRITICAL(&s_log_mux);
+    total = s_total_bytes;
+    portEXIT_CRITICAL(&s_log_mux);
+    return total;
+}