Fix alignment of continuations stack

Author: igrr

cores/esp8266/cont.S

@@ -106,7 +106,7 @@ cont_resume:
 
 cont_norm:
 	/* calculate pointer to cont_ctx.struct_start from sp */
-	l32i	a2,	a1, 8
+	l32i	a2,	a1, 4
 	/* sp <- cont_ctx.sp_ret */
 	l32i	a1, a2, 4
 

cores/esp8266/cont.h

@@ -33,6 +33,8 @@ typedef struct cont_ {
         unsigned* sp_yield;
 
         unsigned* stack_end;
+        unsigned unused1;
+        unsigned unused2;
         unsigned stack_guard1;
 
         unsigned stack[CONT_STACKSIZE / 4];

cores/esp8266/cont_util.c

@@ -25,7 +25,7 @@
 void cont_init(cont_t* cont) {
     cont->stack_guard1 = CONT_STACKGUARD;
     cont->stack_guard2 = CONT_STACKGUARD;
-    cont->stack_end = cont->stack + (sizeof(cont->stack) / 4 - 1);
+    cont->stack_end = cont->stack + (sizeof(cont->stack) / 4);
     cont->struct_start = (unsigned*) cont;
 }
 

cores/esp8266/core_esp8266_main.cpp

@@ -59,7 +59,7 @@ void preloop_update_frequency() {
 extern void (*__init_array_start)(void);
 extern void (*__init_array_end)(void);
 
-static cont_t g_cont;
+cont_t g_cont __attribute__ ((aligned (16)));
 static os_event_t g_loop_queue[LOOP_QUEUE_SIZE];
 
 static uint32_t g_micros_at_task_start;