esp8266: Provide a dedicated variable to disable ets_loop_iter.

So ets_loop_iter is now only disabled when using machine.disable_irq.

esp8266/ets_alt_task.c

 #include <stdio.h>
-#include "xtirq.h"
 #include "osapi.h"
 #include "os_type.h"
 #include "ets_sys.h"
 #include <esp_sdk_ver.h>
 #include "etshal.h"
 #include "user_interface.h"
+#include "ets_alt_task.h"
 
 // Use standard ets_task or alternative impl
 #define USE_ETS_TASK 0
@@ -108,8 +108,10 @@ bool ets_post(uint8 prio, os_signal_t sig, os_param_t param) {
 #endif
 }
 
+int ets_loop_iter_disable = 0;
+
 bool ets_loop_iter(void) {
-    if (query_irq() != 0) {
+    if (ets_loop_iter_disable) {
         return false;
     }
     //static unsigned cnt;

esp8266/ets_alt_task.h

+extern int ets_loop_iter_disable;
 bool ets_loop_iter(void);

esp8266/modmachine.c

@@ -191,13 +191,21 @@ const mp_obj_type_t esp_timer_type = {
     .locals_dict = (mp_obj_t)&esp_timer_locals_dict,
 };
 
+// this bit is unused in the Xtensa PS register
+#define ETS_LOOP_ITER_BIT (12)
+
 STATIC mp_obj_t machine_disable_irq(void) {
-    return mp_obj_new_int(disable_irq());
+    uint32_t state = disable_irq();
+    state = (state & ~(1 << ETS_LOOP_ITER_BIT)) | (ets_loop_iter_disable << ETS_LOOP_ITER_BIT);
+    ets_loop_iter_disable = 1;
+    return mp_obj_new_int(state);
 }
 MP_DEFINE_CONST_FUN_OBJ_0(machine_disable_irq_obj, machine_disable_irq);
 
-STATIC mp_obj_t machine_enable_irq(mp_obj_t state) {
-    enable_irq(mp_obj_get_int(state));
+STATIC mp_obj_t machine_enable_irq(mp_obj_t state_in) {
+    uint32_t state = mp_obj_get_int(state_in);
+    ets_loop_iter_disable = (state >> ETS_LOOP_ITER_BIT) & 1;
+    enable_irq(state & ~(1 << ETS_LOOP_ITER_BIT));
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_1(machine_enable_irq_obj, machine_enable_irq);