UEFI and republicans

1 files changed, 52 insertions, 0 deletions

diff --git a/kernel/efi/gop.c b/kernel/efi/gop.c
new file mode 100644
index 0000000..899bbee
--- /dev/null
+++ b/kernel/efi/gop.c
@@ -0,0 +1,52 @@
+#include <lib.h>
+#include <efi.h>
+#include <comus/efi.h>
+
+static EFI_GRAPHICS_OUTPUT_PROTOCOL *gop = NULL;
+
+EFI_STATUS efi_load_gop(EFI_SYSTEM_TABLE *ST)
+{
+	EFI_STATUS status = EFI_SUCCESS;
+	EFI_GUID gopGuid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+	EFI_GRAPHICS_OUTPUT_MODE_INFORMATION *info;
+	UINTN SizeOfInfo, numModes, nativeMode;
+
+	status = ST->BootServices->LocateProtocol(&gopGuid, NULL, (void **)&gop);
+	if (EFI_ERROR(status))
+		return status;
+
+	status = gop->QueryMode(gop, gop->Mode == NULL ? 0 : gop->Mode->Mode,
+							&SizeOfInfo, &info);
+	if (status == EFI_NOT_STARTED)
+		status = gop->SetMode(gop, 0);
+	if (EFI_ERROR(status))
+		return status;
+
+	nativeMode = gop->Mode->Mode;
+	numModes = gop->Mode->MaxMode;
+
+	// find the best mode
+	UINTN best = nativeMode;
+	UINTN width = 0;
+	for (UINTN i = 0; i < numModes; i++) {
+		status = gop->QueryMode(gop, i, &SizeOfInfo, &info);
+		if (info->PixelFormat != PixelBlueGreenRedReserved8BitPerColor &&
+			info->PixelFormat != PixelRedGreenBlueReserved8BitPerColor)
+			continue;
+		if (info->HorizontalResolution > width) {
+			width = info->HorizontalResolution;
+			best = i;
+		}
+	}
+
+	gop->SetMode(gop, best);
+	if (EFI_ERROR(status))
+		return status;
+
+	return status;
+}
+
+EFI_GRAPHICS_OUTPUT_PROTOCOL *efi_get_gop(void)
+{
+	return gop;
+}