Attempt at reporting something of an 'accurate' unreserved physical page

count. Still needs work.

src/xenia/kernel/xboxkrnl/xboxkrnl_memory.cc

@@ -444,13 +444,30 @@ SHIM_CALL MmQueryStatistics_shim(PPCContext* ppc_context,
   // this won't work :/
   stats->size = size;
 
-  stats->total_physical_pages = 0x00020000;
+  stats->total_physical_pages = 0x00020000;  // 512mb / 4kb pages
   stats->kernel_pages = 0x00000300;
 
-  stats->title.available_pages = 0x00013300;
-  stats->title.total_virtual_memory_bytes = 0x2FFF0000;
-  stats->title.reserved_virtual_memory_bytes = 0x00160000;
-  stats->title.physical_pages = 0x00001000;
+  // TODO(gibbed): maybe use LookupHeapByType instead?
+  auto physA = kernel_memory()->LookupHeap(0xA0000000);
+  auto physC = kernel_memory()->LookupHeap(0xC0000000);
+  auto physE = kernel_memory()->LookupHeap(0xE0000000);
+  assert_not_null(physA);
+  assert_not_null(physC);
+  assert_not_null(physE);
+
+  uint32_t available_pages = 0;
+  available_pages +=
+      (physA->GetUnreservedPageCount() * physA->page_size()) / 4096;
+  available_pages +=
+      (physC->GetUnreservedPageCount() * physC->page_size()) / 4096;
+  available_pages +=
+      (physE->GetUnreservedPageCount() * physE->page_size()) / 4096;
+
+  stats->title.available_pages = available_pages;
+  stats->title.total_virtual_memory_bytes = 0x2FFF0000;  // TODO(gibbed): FIXME
+  stats->title.reserved_virtual_memory_bytes =
+      0x00160000;                            // TODO(gibbed): FIXME
+  stats->title.physical_pages = 0x00001000;  // TODO(gibbed): FIXME
   stats->title.pool_pages = 0x00000010;
   stats->title.stack_pages = 0x00000100;
   stats->title.image_pages = 0x00000100;

src/xenia/memory.cc

@@ -551,6 +551,32 @@ void BaseHeap::DumpMap() {
   }
 }
 
+uint32_t BaseHeap::GetUnreservedPageCount() {
+  auto global_lock = global_critical_region_.Acquire();
+  uint32_t count = 0;
+  bool is_empty_span = false;
+  uint32_t empty_span_start = 0;
+  uint32_t size = uint32_t(page_table_.size());
+  for (uint32_t i = 0; i < size; ++i) {
+    auto& page = page_table_[i];
+    if (!page.state) {
+      if (!is_empty_span) {
+        is_empty_span = true;
+        empty_span_start = i;
+      }
+      continue;
+    }
+    if (is_empty_span) {
+      count += i - empty_span_start;
+    }
+    i += page.region_page_count - 1;
+  }
+  if (is_empty_span) {
+    count += size - empty_span_start;
+  }
+  return count;
+}
+
 bool BaseHeap::Save(ByteStream* stream) {
   XELOGD("Heap %.8X-%.8X", heap_base_, heap_base_ + heap_size_);
 

src/xenia/memory.h

@@ -101,6 +101,8 @@ class BaseHeap {
   // Dumps information about all allocations within the heap to the log.
   void DumpMap();
 
+  uint32_t GetUnreservedPageCount();
+
   // Allocates pages with the given properties and allocation strategy.
   // This can reserve and commit the pages as well as set protection modes.
   // This will fail if not enough contiguous pages can be found.