1 files changed, 59 insertions, 0 deletions
diff --git a/src/helper.hh b/src/helper.hh
new file mode 100644
index 0000000..468f146
--- /dev/null
+++ b/src/helper.hh
@@ -0,0 +1,59 @@
+#ifndef HELPER_HH_
+#define HELPER_HH_
+
+#include <vulkan/vk_layer.h>
+#include <vulkan/vulkan.h>
+
+#include <cstdint>
+
+namespace low_latency {
+
+// Small templates which allow us to SFINAE find pNext structs.
+template <typename T>
+static T* find_next(void* const head, const VkStructureType& stype) {
+    for (auto i = reinterpret_cast<VkBaseOutStructure*>(head)->pNext; i;
+         i = i->pNext) {
+
+        if (i->sType == stype) {
+            return reinterpret_cast<T*>(i);
+        }
+    }
+    return nullptr;
+}
+
+template <typename T>
+static const T* find_next(const void* const head,
+                          const VkStructureType& stype) {
+
+    for (auto i = reinterpret_cast<const VkBaseInStructure*>(head)->pNext; i;
+         i = i->pNext) {
+
+        if (i->sType == stype) {
+            return reinterpret_cast<const T*>(i);
+        }
+    }
+    return nullptr;
+}
+
+template <typename T>
+static const T* find_link(const void* const head,
+                          const VkStructureType& stype) {
+    for (auto info = find_next<T>(head, stype); info;
+         info = find_next<T>(info, stype)) {
+
+        if (info->function == VK_LAYER_LINK_INFO) {
+            return reinterpret_cast<const T*>(info);
+        }
+    }
+    return nullptr;
+}
+
+template <typename T> std::uint64_t extract_present_id(const T& submit) {
+    const auto lspi = find_next<VkLatencySubmissionPresentIdNV>(
+        &submit, VK_STRUCTURE_TYPE_LATENCY_SUBMISSION_PRESENT_ID_NV);
+    return lspi ? lspi->presentID : 0;
+}
+
+} // namespace low_latency
+
+#endif
+\ No newline at end of file