Add and use atomic_memcpy for the AVR backend

compiler/obc/c/async_avr.ml

@@ -3,7 +3,7 @@ open C
 open Obc
 open Async_backend
 
-module PosixBackend : AsyncBackend =
+module AvrBackend : AsyncBackend =
 struct
   let qn_append q suffix =
     { qual = q.qual; name = q.name ^ suffix }
@@ -15,7 +15,9 @@ struct
     (* TODO(Arduino): add const qualifier *)
     let arg_ty = Cty_ptr (Cty_id (qn_append cd.cd_name suffix)) in
     let sizeof = Cfun_call ("sizeof", [Cderef (Cvar "src")]) in
-    let memcpy = Cfun_call ("memcpy", [Cvar "dest"; Cvar "src"; sizeof]) in
+    let memcpy =
+      Cfun_call ("atomic_memcpy", [Cvar "dest"; Cvar "src"; sizeof])
+    in
     Cfundef {
       C.f_name = func_name;
       f_retty = Cty_void;

compiler/obc/c/cgen.ml

@@ -34,7 +34,7 @@ open Idents
 open Obc
 open Obc_utils
 open Types
-open Async_posix
+open Async_avr
 
 open Modules
 open Signature
@@ -891,8 +891,8 @@ let cdefs_and_cdecls_of_class_def cd =
   let step_fun_def = fun_def_of_step_fun cd.cd_name
     cd.cd_objs cd.cd_mems cd.cd_objs step_m in
   (* TODO(Arduino): let the user choose the backend they want *)
-  let copy_in_def = PosixBackend.gen_copy_func_in cd in
-  let copy_out_def = PosixBackend.gen_copy_func_out cd in
+  let copy_in_def = AvrBackend.gen_copy_func_in cd in
+  let copy_out_def = AvrBackend.gen_copy_func_out cd in
   let async_step_fun_def = async_fun_def_of_step_fun cd.cd_name
     cd.cd_objs cd.cd_mems cd.cd_objs step_m (cdef_name copy_in_def)
     (cdef_name copy_out_def) in

lib/c/pervasives.h

@@ -31,6 +31,10 @@
 
 #ifndef DECADES_PERVASIVES_H
 #define DECADES_PERVASIVES_H
+#include <string.h>
+#ifdef __AVR__
+#include <util/atomic.h>
+#endif
 
 typedef float real;
 
@@ -41,5 +45,13 @@ static inline int between(int idx, int n)
   return o;
 }
 
+#ifdef __AVR__
+static inline void atomic_memcpy(void *dest, const void *src, size_t size) {
+  ATOMIC_BLOCK(ATOMIC_FORCEON) {
+    memcpy(dest, src, size);
+  }
+}
+#endif
+
 #endif