Added some const modifiers.

Author: arbv

avrcontext.h

@@ -9,12 +9,6 @@
 
 #ifdef __AVR__
 
-/*
-It is highly unlikely to understand the following code without:
-a) basic understanding of AVR assembly language;
-b) reading about avr-gcc's ABI beforehand (https://gcc.gnu.org/wiki/avr-gcc).
-*/
-
 /* AVR machine context definition. Please keep the corresponding routines/macros synchronised with this definition. */
 typedef struct avr_context_t_ {
  uint8_t sreg;
@@ -35,6 +29,28 @@ typedef struct avr_context_t_ {
  } sp;
 } avr_context_t;
 
+#ifdef __cplusplus
+extern "C" {
+#endif /*__cplusplus */
+
+extern void avr_getcontext(avr_context_t *cp);
+extern void avr_setcontext(const avr_context_t *cp);
+extern void avr_swapcontext(avr_context_t *oucp, const avr_context_t *cp);
+extern void avr_makecontext(avr_context_t *cp,
+ void *stackp, const size_t stack_size,
+ const avr_context_t *successor_cp,
+ void (*funcp)(void *), void *funcargp);
+
+#ifdef __cplusplus
+}
+#endif /*__cplusplus */
+
+/*
+It is highly unlikely to understand the following code without:
+a) basic understanding of AVR assembly language;
+b) reading about avr-gcc's ABI beforehand (https://gcc.gnu.org/wiki/avr-gcc).
+*/
+
 /* Some utility macros, most of them define offsets to simplify working on the
  machine context structure from within assembly code. */
 #define AVR_CONTEXT_ASMCONST(name, value)\
@@ -290,22 +306,6 @@ please make sure that you understand how they work.
  "lds ZL, " #global_context_pointer "\n" \
  "lds ZH, " #global_context_pointer " + 1\n")
 
-#ifdef __cplusplus
-extern "C" {
-#endif /*__cplusplus */
-
-extern void avr_getcontext(avr_context_t *cp);
-extern void avr_setcontext(avr_context_t *cp);
-extern void avr_swapcontext(avr_context_t *oucp, avr_context_t *cp);
-extern void avr_makecontext(avr_context_t *cp,
- void *stackp, size_t stack_size,
- avr_context_t *successor_cp,
- void (*funcp)(void *), void *funcargp);
-
-#ifdef __cplusplus
-}
-#endif /*__cplusplus */
-
 #endif /* __AVR__ */
 
 #endif /* AVRCONTEXT_H */

avrcontext_impl.h

@@ -20,8 +20,8 @@ void avr_getcontext(avr_context_t *cp)
  asm volatile ("ret\n");
 }
 
-void avr_setcontext(avr_context_t *cp) __attribute__ ((naked));
-void avr_setcontext(avr_context_t *cp)
+void avr_setcontext(const avr_context_t *cp) __attribute__ ((naked));
+void avr_setcontext(const avr_context_t *cp)
 {
  (void)cp; /* to avoid compiler warnings */
  AVR_RESTORE_CONTEXT(
@@ -31,8 +31,8 @@ void avr_setcontext(avr_context_t *cp)
 }
 
 
-void avr_swapcontext(avr_context_t *oucp, avr_context_t *ucp) __attribute__ ((naked));
-void avr_swapcontext(avr_context_t *oucp, avr_context_t *ucp)
+void avr_swapcontext(avr_context_t *oucp, const avr_context_t *ucp) __attribute__ ((naked));
+void avr_swapcontext(avr_context_t *oucp, const avr_context_t *ucp)
 {
  (void)oucp; /* to avoid compiler warnings */
  (void)ucp;
@@ -49,17 +49,17 @@ void avr_swapcontext(avr_context_t *oucp, avr_context_t *ucp)
 #ifdef __cplusplus
 extern "C" {
 #endif /*__cplusplus **/
-static void avr_makecontext_callfunc(avr_context_t *successor, void (*func)(void *), void *funcarg);
+static void avr_makecontext_callfunc(const avr_context_t *successor, void (*func)(void *), void *funcarg);
 #ifdef __cplusplus
 }
 #endif /*__cplusplus */
-static void avr_makecontext_callfunc(avr_context_t *successor, void (*func)(void *), void *funcarg)
+static void avr_makecontext_callfunc(const avr_context_t *successor, void (*func)(void *), void *funcarg)
 {
  func(funcarg);
  avr_setcontext(successor);
 }
 
-void avr_makecontext(avr_context_t *cp, void *stackp, size_t stack_size, avr_context_t *successor_cp, void (*funcp)(void *), void *funcargp)
+void avr_makecontext(avr_context_t *cp, void *stackp, const size_t stack_size, const avr_context_t *successor_cp, void (*funcp)(void *), void *funcargp)
 {
  uint16_t addr;
  uint8_t *p = (uint8_t *)&addr;