union

Author: pavel-kirienko

libudpard/udpard.h

@@ -158,17 +158,21 @@ typedef struct udpard_bytes_mut_t
     void*  data;
 } udpard_bytes_mut_t;
 
+/// The size can be changed arbitrarily. This value is compromise between copy size and footprint and utility.
+#define UDPARD_USER_CONTEXT_PTR_COUNT 6
+
 /// The library carries the user-provided context from inputs to outputs without interpreting it,
 /// allowing the application to associate its own data with various entities inside the library.
-typedef struct udpard_user_context_t
+typedef union udpard_user_context_t
 {
-    void* data[6]; ///< The size is chosen rather arbitrarily; the library doesn't care. Can be configured ad-hoc.
+    void* ptr[UDPARD_USER_CONTEXT_PTR_COUNT];
+    unsigned char bytes[sizeof(void*) * UDPARD_USER_CONTEXT_PTR_COUNT];
 } udpard_user_context_t;
 #ifdef __cplusplus
 #define UDPARD_USER_CONTEXT_NULL \
     udpard_user_context_t {}
 #else
-#define UDPARD_USER_CONTEXT_NULL ((udpard_user_context_t){ .data = { NULL } })
+#define UDPARD_USER_CONTEXT_NULL ((udpard_user_context_t){ .ptr = { NULL } })
 #endif
 
 /// Zeros if invalid/unset/unavailable.

tests/src/helpers.h

@@ -68,7 +68,7 @@ static inline udpard_bytes_scattered_t make_scattered(const void* const data, co
 static inline udpard_user_context_t make_user_context(void* const obj)
 {
     udpard_user_context_t out = UDPARD_USER_CONTEXT_NULL;
-    out.data[0]               = obj;
+    out.ptr[0]                = obj;
     return out;
 }
 

tests/src/test_e2e_api.cpp

@@ -72,7 +72,7 @@ constexpr udpard_tx_vtable_t tx_vtable{ .eject = &capture_tx_frame };
 // Feedback callback records completion.
 void record_feedback(udpard_tx_t*, const udpard_tx_feedback_t fb)
 {
-    auto* st = static_cast<FeedbackState*>(fb.user.data[0]);
+    auto* st = static_cast<FeedbackState*>(fb.user.ptr[0]);
     if (st != nullptr) {
         st->count++;
         st->success     = fb.success;

tests/src/test_e2e_edge.cpp

@@ -55,7 +55,7 @@ constexpr udpard_tx_vtable_t tx_vtable{ .eject = &capture_tx_frame };
 
 void fb_record(udpard_tx_t*, const udpard_tx_feedback_t fb)
 {
-    auto* st = static_cast<FbState*>(fb.user.data[0]);
+    auto* st = static_cast<FbState*>(fb.user.ptr[0]);
     if (st != nullptr) {
         st->count++;
         st->success = fb.success;

tests/src/test_e2e_random.cpp

@@ -107,7 +107,7 @@ constexpr udpard_tx_vtable_t tx_vtable{ .eject = &capture_tx_frame };
 
 void record_feedback(udpard_tx_t*, const udpard_tx_feedback_t fb)
 {
-    auto* ctx = static_cast<Context*>(fb.user.data[0]);
+    auto* ctx = static_cast<Context*>(fb.user.ptr[0]);
     if (ctx != nullptr) {
         if (fb.success) {
             ctx->reliable_feedback_success++;

tests/src/test_e2e_responses.cpp

@@ -63,7 +63,7 @@ struct FeedbackState
 
 void record_feedback(udpard_tx_t*, const udpard_tx_feedback_t fb)
 {
-    auto* st = static_cast<FeedbackState*>(fb.user.data[0]);
+    auto* st = static_cast<FeedbackState*>(fb.user.ptr[0]);
     if (st != nullptr) {
         st->count++;
         st->success     = fb.success;

tests/src/test_intrusive_tx.c

@@ -58,7 +58,7 @@ static bool eject_with_log(udpard_tx_t* const tx, udpard_tx_ejection_t* const ej
 static void record_feedback(udpard_tx_t* const tx, const udpard_tx_feedback_t fb)
 {
     (void)tx;
-    feedback_state_t* const st = (feedback_state_t*)fb.user.data[0];
+    feedback_state_t* const st = (feedback_state_t*)fb.user.ptr[0];
     if (st != NULL) {
         st->count++;
         st->last = fb;