From dd57a31d389436949a8937624cf6a197ed8d16e4 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Mon, 14 Mar 2022 21:43:40 -0400
Subject: [PATCH] HEL: Add heap module; locate GOP handle

---
 src/hel/heap.d | 19 +++++++++++++++++++
 src/hel/hel.d  | 27 +++++++++++++++++++++++----
 2 files changed, 42 insertions(+), 4 deletions(-)
 create mode 100644 src/hel/heap.d

diff --git a/src/hel/heap.d b/src/hel/heap.d
new file mode 100644
index 0000000..b0b5fe2
--- /dev/null
+++ b/src/hel/heap.d
@@ -0,0 +1,19 @@
+private __gshared align(4096) ubyte[512 * 1024] g_heap;
+private __gshared size_t g_heap_index;
+
+ubyte * heap_base()
+{
+    return &g_heap[g_heap_index];
+}
+
+size_t heap_free()
+{
+    return g_heap.sizeof - g_heap_index;
+}
+
+ubyte * heap_consume(size_t size)
+{
+    ubyte * rv = &g_heap[g_heap_index];
+    g_heap_index += (size + 4095u) & 0xFFFFFFFFFFFFF000u;
+    return rv;
+}
diff --git a/src/hel/hel.d b/src/hel/hel.d
index 4199ea3..e24e1ad 100644
--- a/src/hel/hel.d
+++ b/src/hel/hel.d
@@ -1,8 +1,19 @@
 import uefi;
 import output;
+import heap;
 
 __gshared EFI_SYSTEM_TABLE * g_st;
 
+private void wait_key()
+{
+    writeln("Press any key...");
+    g_st.ConIn.Reset(g_st.ConIn, FALSE);
+    EFI_INPUT_KEY key;
+    while (g_st.ConIn.ReadKeyStroke(g_st.ConIn, &key) == EFI_NOT_READY)
+    {
+    }
+}
+
 extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
 {
     g_st = st;
@@ -11,13 +22,21 @@ extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
 
     writeln("HOS EFI loader");
     writeln("Firmware vendor: '%S', version: 0x%x", st.FirmwareVendor, st.FirmwareVendor);
-    writeln("Press any key...");
 
-    st.ConIn.Reset(st.ConIn, FALSE);
-    EFI_INPUT_KEY key;
-    while (st.ConIn.ReadKeyStroke(st.ConIn, &key) == EFI_NOT_READY)
+    UINTN buffer_size = heap_free();
+    EFI_GUID gop_guid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+    EFI_HANDLE * handles = cast(EFI_HANDLE *)heap_base();
+    EFI_STATUS status = st.BootServices.LocateHandle(ByProtocol,
+            &gop_guid, null, &buffer_size, handles);
+    if (status != EFI_SUCCESS)
     {
+        writeln("LocateHandle: error %u", status);
+        wait_key();
+        return EFI_SUCCESS;
     }
+    EFI_HANDLE gop_handle = handles[0];
+
+    wait_key();
 
     return EFI_SUCCESS;
 }