缩小变量作用域：消除18处variableScope，声明移入实际使用块

App/util/ringbuf.c

@@ -91,13 +91,12 @@ size_t ringbuf_peek(const ringbuf_t *rb, uint8_t *data, size_t len)
 {
     size_t n = 0;
     size_t i = 0;
-    size_t idx;
 
     n = ringbuf_avail(rb);
     n = (n < len) ? n : len;
 
     for (i = 0; i < n; i++) {
-        idx = (rb->tail + i) % rb->size;
+        size_t idx = (rb->tail + i) % rb->size;
         data[i] = rb->buf[idx];
     }