feat(heap): add function to get DRAM region free size

components/heap/port/esp8266/esp_heap_init.c

@@ -13,12 +13,23 @@
 // limitations under the License.
 
 #include "esp_heap_caps.h"
+#include "esp_attr.h"
 
 #define HEAP_REGION_IRAM_MIN 512
 #define HEAP_REGION_IRAM_MAX 0x00010000
 
 heap_region_t g_heap_region[HEAP_REGIONS_MAX];
 
+size_t IRAM_ATTR heap_caps_get_dram_free_size(void)
+{
+#ifndef CONFIG_HEAP_DISABLE_IRAM
+    extern size_t g_heap_region_num;
+
+    return g_heap_region[g_heap_region_num - 1].free_bytes;
+#else
+    return g_heap_region[0].free_bytes;
+#endif
+}
 
 /**
  * @brief Initialize the capability-aware heap allocator.

components/heap/port/esp8266/include/esp_heap_port.h

@@ -14,6 +14,12 @@
 
 #pragma once
 
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define _heap_caps_lock(_num)               \
 {                                           \
     extern void vPortETSIntrLock(void);     \
@@ -32,3 +38,13 @@
     esp_task_wdt_reset();                   \
 }
 
+/**
+ * @brief Get the total free size of DRAM region
+ *
+ * @return Amount of free bytes in DRAM region
+ */
+size_t heap_caps_get_dram_free_size(void);
+
+#ifdef __cplusplus
+}
+#endif