Put VbDisplay* functions into their own file.

This refactoring will enable us to test and mock them separately from the
rest of the vboot_api functions.

BUG=chromium-os:17564
TEST=manual

Built for ARM, ran "vbexport_test display" at U-Boot prompt. Still works.

Change-Id: I2ddb01d3e981603f371aaa7317184457bdff48ac
Reviewed-on: http://gerrit.chromium.org/gerrit/6422
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Tested-by: Bill Richardson <wfrichar@chromium.org>

4 files changed, 360 insertions, 317 deletions

diff --git a/firmware/Makefile b/firmware/Makefile
index f72000a1..379252d0 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -64,6 +64,7 @@ LIB_SRCS = \
 	./lib/vboot_api_firmware.c \
 	./lib/vboot_api_kernel.c \
 	./lib/vboot_common.c \
+	./lib/vboot_display.c \
 	./lib/vboot_firmware.c \
 	./lib/vboot_kernel.c \
 	./lib/vboot_nvstorage.c
diff --git a/firmware/lib/include/vboot_display.h b/firmware/lib/include/vboot_display.h
new file mode 100644
index 00000000..57688aed
--- /dev/null
+++ b/firmware/lib/include/vboot_display.h
@@ -0,0 +1,23 @@
+/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Display functions used in kernel selection.
+ */
+
+#ifndef VBOOT_REFERENCE_VBOOT_DISPLAY_H_
+#define VBOOT_REFERENCE_VBOOT_DISPLAY_H_
+
+#include "vboot_api.h"
+#include "vboot_nvstorage.h"
+
+VbError_t VbDisplayScreenFromGBB(VbCommonParams* cparams, uint32_t screen,
+                                 VbNvContext *vncptr);
+VbError_t VbDisplayScreen(VbCommonParams* cparams, uint32_t screen, int force,
+                          VbNvContext *vncptr);
+VbError_t VbDisplayDebugInfo(VbCommonParams* cparams, VbNvContext *vncptr);
+VbError_t VbCheckDisplayKey(VbCommonParams* cparams, uint32_t key,
+                            VbNvContext *vncptr);
+
+#endif /* VBOOT_REFERENCE_VBOOT_DISPLAY_H_ */
+
diff --git a/firmware/lib/vboot_api_kernel.c b/firmware/lib/vboot_api_kernel.c
index e1fce4fd..99ad7999 100644
--- a/firmware/lib/vboot_api_kernel.c
+++ b/firmware/lib/vboot_api_kernel.c
@@ -11,12 +11,11 @@
 #include "utility.h"
 #include "vboot_api.h"
 #include "vboot_common.h"
+#include "vboot_display.h"
 #include "vboot_nvstorage.h"
 
 
 /* Global variables */
-static uint32_t disp_current_screen = VB_SCREEN_BLANK;
-static uint32_t disp_width = 0, disp_height = 0;
 static VbNvContext vnc;
 
 
@@ -35,312 +34,6 @@ static void VbSetRecoveryRequest(uint32_t recovery_request) {
 }
 
 
-/* Get the number of localizations in the GBB bitmap data. */
-static VbError_t VbGetLocalizationCount(VbCommonParams* cparams,
-                                        uint32_t* count) {
-  GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)cparams->gbb_data;
-  BmpBlockHeader* hdr;
-
-  /* Default to 0 on error */
-  *count = 0;
-
-  /* Make sure the bitmap data is inside the GBB and is non-zero in size */
-  if (0 == gbb->bmpfv_size ||
-      gbb->bmpfv_offset > cparams->gbb_size ||
-      gbb->bmpfv_offset + gbb->bmpfv_size > cparams->gbb_size) {
-    return VBERROR_INVALID_GBB;
-  }
-
-  /* Sanity-check the bitmap block header */
-  hdr = (BmpBlockHeader *)(((uint8_t*)gbb) + gbb->bmpfv_offset);
-  if ((0 != Memcmp(hdr->signature, BMPBLOCK_SIGNATURE,
-                   BMPBLOCK_SIGNATURE_SIZE)) ||
-      (hdr->major_version > BMPBLOCK_MAJOR_VERSION) ||
-      ((hdr->major_version == BMPBLOCK_MAJOR_VERSION) &&
-       (hdr->minor_version > BMPBLOCK_MINOR_VERSION))) {
-    return VBERROR_INVALID_BMPFV;
-  }
-
-  *count = hdr->number_of_localizations;
-  return VBERROR_SUCCESS;
-}
-
-
-/* Display a screen from the GBB. */
-static VbError_t VbDisplayScreenFromGBB(VbCommonParams* cparams,
-                                        uint32_t screen) {
-  GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)cparams->gbb_data;
-  uint8_t* bmpfv = NULL;
-  uint8_t* fullimage = NULL;
-  BmpBlockHeader* hdr;
-  ScreenLayout* layout;
-  ImageInfo* image_info;
-  uint32_t screen_index;
-  uint32_t localization = 0;
-  VbError_t retval = VBERROR_UNKNOWN;  /* Assume error until proven ok */
-  uint32_t inoutsize;
-  uint32_t offset;
-  uint32_t i;
-
-  /* Make sure the bitmap data is inside the GBB and is non-zero in size */
-  if (0 == gbb->bmpfv_size ||
-      gbb->bmpfv_offset > cparams->gbb_size ||
-      gbb->bmpfv_offset + gbb->bmpfv_size > cparams->gbb_size) {
-    VBDEBUG(("VbDisplayScreenFromGBB(): invalid bmpfv offset/size\n"));
-    return VBERROR_INVALID_GBB;
-  }
-
-  /* Copy bitmap data from GBB into RAM for speed */
-  bmpfv = (uint8_t*)VbExMalloc(gbb->bmpfv_size);
-  Memcpy(bmpfv, ((uint8_t*)gbb) + gbb->bmpfv_offset, gbb->bmpfv_size);
-
-  /* Sanity-check the bitmap block header */
-  hdr = (BmpBlockHeader *)bmpfv;
-  if ((0 != Memcmp(hdr->signature, BMPBLOCK_SIGNATURE,
-                   BMPBLOCK_SIGNATURE_SIZE)) ||
-      (hdr->major_version > BMPBLOCK_MAJOR_VERSION) ||
-      ((hdr->major_version == BMPBLOCK_MAJOR_VERSION) &&
-       (hdr->minor_version > BMPBLOCK_MINOR_VERSION))) {
-    VBDEBUG(("VbDisplayScreenFromGBB(): invalid/too new bitmap header\n"));
-    retval = VBERROR_INVALID_BMPFV;
-    goto VbDisplayScreenFromGBB_exit;
-  }
-
-  /* Translate screen ID into index.  Note that not all screens are in the
-   * GBB. */
-  /* TODO: ensure screen IDs match indices?  Having this translation
-   * here is awful. */
-  switch (screen) {
-    case VB_SCREEN_DEVELOPER_WARNING:
-      screen_index = 0;
-      break;
-    case VB_SCREEN_RECOVERY_REMOVE:
-      screen_index = 1;
-      break;
-    case VB_SCREEN_RECOVERY_NO_GOOD:
-      screen_index = 2;
-      break;
-    case VB_SCREEN_RECOVERY_INSERT:
-      screen_index = 3;
-      break;
-    case VB_SCREEN_BLANK:
-    case VB_SCREEN_DEVELOPER_EGG:
-    default:
-      /* Screens which aren't in the GBB */
-      VBDEBUG(("VbDisplayScreenFromGBB(): screen %d not in the GBB\n",
-               (int)screen));
-      retval = VBERROR_INVALID_SCREEN_INDEX;
-      goto VbDisplayScreenFromGBB_exit;
-  }
-  if (screen_index >= hdr->number_of_screenlayouts) {
-    VBDEBUG(("VbDisplayScreenFromGBB(): screen %d index %d not in the GBB\n",
-             (int)screen, (int)screen_index));
-    retval = VBERROR_INVALID_SCREEN_INDEX;
-    goto VbDisplayScreenFromGBB_exit;
-  }
-
-  /* Clip localization to the number of localizations present in the GBB */
-  VbNvGet(&vnc, VBNV_LOCALIZATION_INDEX, &localization);
-  if (localization >= hdr->number_of_localizations) {
-    localization = 0;
-    VbNvSet(&vnc, VBNV_LOCALIZATION_INDEX, localization);
-  }
-
-  /* Calculate offset of screen layout = start of screen stuff +
-   * correct locale + correct screen. */
-  offset = sizeof(BmpBlockHeader) +
-      localization * hdr->number_of_screenlayouts * sizeof(ScreenLayout) +
-      screen_index * sizeof(ScreenLayout);
-  VBDEBUG(("VbDisplayScreenFromGBB(): scr_%d_%d at offset 0x%x\n",
-           localization, screen_index, offset));
-  layout = (ScreenLayout*)(bmpfv + offset);
-
-  /* Display all bitmaps for the image */
-  for (i = 0; i < MAX_IMAGE_IN_LAYOUT; i++) {
-    if (layout->images[i].image_info_offset) {
-      offset = layout->images[i].image_info_offset;
-      image_info = (ImageInfo*)(bmpfv + offset);
-      VBDEBUG(("VbDisplayScreenFromGBB: image %d: %dx%d+%d+%d %d/%d"
-               "tag %d at 0x%x\n",
-               i, image_info->width, image_info->height,
-               layout->images[i].x, layout->images[i].y,
-               image_info->compressed_size, image_info->original_size,
-               image_info->tag, offset));
-      if (COMPRESS_NONE != image_info->compression) {
-        inoutsize = image_info->original_size;
-        fullimage = (uint8_t*)VbExMalloc(inoutsize);
-        retval = VbExDecompress(bmpfv + offset + sizeof(ImageInfo),
-                                image_info->compressed_size,
-                                image_info->compression,
-                                fullimage, &inoutsize);
-        if (VBERROR_SUCCESS != retval) {
-          VbExFree(fullimage);
-          goto VbDisplayScreenFromGBB_exit;
-        }
-        retval = VbExDisplayImage(layout->images[i].x, layout->images[i].y,
-                                  fullimage, inoutsize);
-        VbExFree(fullimage);
-      } else {
-        retval = VbExDisplayImage(layout->images[i].x, layout->images[i].y,
-                                  bmpfv + offset + sizeof(ImageInfo),
-                                  image_info->original_size);
-      }
-      if (VBERROR_SUCCESS != retval)
-        goto VbDisplayScreenFromGBB_exit;
-    }
-  }
-
-  /* Successful if all bitmaps displayed */
-  retval = VBERROR_SUCCESS;
-
-VbDisplayScreenFromGBB_exit:
-
-  /* Free the bitmap data copy */
-  VbExFree(bmpfv);
-  return retval;
-}
-
-
-/* Display a screen, initializing the display if necessary.  If force!=0,
- * redisplays the screen even if it's the same as the current screen. */
-static VbError_t VbDisplayScreen(VbCommonParams* cparams, uint32_t screen,
-                                 int force) {
-  VbError_t retval;
-
-  VBDEBUG(("VbDisplayScreen(%d, %d)\n", (int)screen, force));
-
-  /* Initialize display if necessary */
-  if (!disp_width) {
-    retval = VbExDisplayInit(&disp_width, &disp_height);
-    if (VBERROR_SUCCESS != retval)
-      return retval;
-  }
-
-  /* If the requested screen is the same as the current one, we're done. */
-  if (disp_current_screen == screen && 0 == force)
-    return VBERROR_SUCCESS;
-
-  /* If the screen is blank, turn off the backlight; else turn it on. */
-  VbExDisplayBacklight(VB_SCREEN_BLANK == screen ? 0 : 1);
-
-  /* Request the screen */
-  disp_current_screen = screen;
-
-  /* Look in the GBB first */
-  if (VBERROR_SUCCESS == VbDisplayScreenFromGBB(cparams, screen))
-    return VBERROR_SUCCESS;
-
-  /* If the screen wasn't in the GBB bitmaps, fall back to a default screen. */
-  return VbExDisplayScreen(screen);
-}
-
-
-#define DEBUG_INFO_SIZE 512
-
-/* Display debug info to the screen */
-static VbError_t VbDisplayDebugInfo(VbCommonParams* cparams) {
-  VbSharedDataHeader* shared = (VbSharedDataHeader*)cparams->shared_data_blob;
-  GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)cparams->gbb_data;
-  char buf[DEBUG_INFO_SIZE] = "";
-  uint32_t used = 0;
-  uint32_t i;
-
-  /* Redisplay the current screen, to overwrite any previous debug output */
-  VbDisplayScreen(cparams, disp_current_screen, 1);
-
-  /* Add hardware ID */
-  used += Strncat(buf + used, "HWID: ", DEBUG_INFO_SIZE - used);
-  if (0 == gbb->hwid_size ||
-      gbb->hwid_offset > cparams->gbb_size ||
-      gbb->hwid_offset + gbb->hwid_size > cparams->gbb_size) {
-    VBDEBUG(("VbCheckDisplayKey(): invalid hwid offset/size\n"));
-    used += Strncat(buf + used, "(INVALID)", DEBUG_INFO_SIZE - used);
-  } else {
-    used += Strncat(buf + used, (char*)((uint8_t*)gbb + gbb->hwid_offset),
-                    DEBUG_INFO_SIZE - used);
-  }
-
-  /* Add recovery reason */
-  used += Strncat(buf + used, "\nrecovery_reason: 0x", DEBUG_INFO_SIZE - used);
-  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
-                         shared->recovery_reason, 16, 2);
-
-  /* Add VbSharedData flags */
-  used += Strncat(buf + used, "\nVbSD.flags: 0x", DEBUG_INFO_SIZE - used);
-  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
-                         shared->flags, 16, 8);
-
-  /* Add raw contents of VbNvStorage */
-  used += Strncat(buf + used, "\nVbNv.raw:", DEBUG_INFO_SIZE - used);
-  for (i = 0; i < VBNV_BLOCK_SIZE; i++) {
-    used += Strncat(buf + used, " ", DEBUG_INFO_SIZE - used);
-    used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
-                           vnc.raw[i], 16, 2);
-  }
-
-  /* Add dev_boot_usb flag */
-  VbNvGet(&vnc, VBNV_DEV_BOOT_USB, &i);
-  used += Strncat(buf + used, "\ndev_boot_usb: ", DEBUG_INFO_SIZE - used);
-  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used, i, 10, 0);
-
-  /* Add TPM versions */
-  used += Strncat(buf + used, "\nTPM: fwver=0x", DEBUG_INFO_SIZE - used);
-  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
-                         shared->fw_version_tpm, 16, 8);
-  used += Strncat(buf + used, " kernver=0x", DEBUG_INFO_SIZE - used);
-  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
-                         shared->kernel_version_tpm, 16, 8);
-
-  /* Add GBB flags */
-  used += Strncat(buf + used, "\ngbb.flags: 0x", DEBUG_INFO_SIZE - used);
-  if (gbb->major_version == GBB_MAJOR_VER && gbb->minor_version >= 1) {
-    used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
-                           gbb->flags, 16, 8);
-  } else {
-    used += Strncat(buf + used, "0 (default)", DEBUG_INFO_SIZE - used);
-  }
-
-  /* Make sure we finish with a newline */
-  used += Strncat(buf + used, "\n", DEBUG_INFO_SIZE - used);
-
-  /* TODO: add more interesting data:
-   * - SHA1 of kernel subkey (assuming we always set it in VbSelectFirmware,
-   *   even in recovery mode, where we just copy it from the root key)
-   * - Information on current disks */
-
-  buf[DEBUG_INFO_SIZE - 1] = '\0';
-  return VbExDisplayDebugInfo(buf);
-}
-
-
-static VbError_t VbCheckDisplayKey(VbCommonParams* cparams, uint32_t key) {
-
-  if ('\t' == key) {
-    /* Tab = display debug info */
-    return VbDisplayDebugInfo(cparams);
-
-  } else if (VB_KEY_LEFT == key || VB_KEY_RIGHT == key) {
-    /* Arrow keys = change localization */
-    uint32_t loc = 0;
-    uint32_t count = 0;
-
-    VbNvGet(&vnc, VBNV_LOCALIZATION_INDEX, &loc);
-    if (VBERROR_SUCCESS != VbGetLocalizationCount(cparams, &count))
-      loc = 0;  /* No localization count (bad GBB?), so set to 0 (default) */
-    else if (VB_KEY_RIGHT == key)
-      loc = (loc < count - 1 ? loc + 1 : 0);
-    else
-      loc = (loc > 0 ? loc - 1 : count - 1);
-    VBDEBUG(("VbCheckDisplayKey() - change localization to %d\n", (int)loc));
-    VbNvSet(&vnc, VBNV_LOCALIZATION_INDEX, loc);
-
-    /* Force redraw of current screen */
-    return VbDisplayScreen(cparams, disp_current_screen, 1);
-  }
-
-  return VBERROR_SUCCESS;
-}
-
 
 /* Attempt loading a kernel from the specified type(s) of disks.  If
  * successful, sets p->disk_handle to the disk for the kernel and returns
@@ -438,7 +131,7 @@ VbError_t VbBootDeveloper(VbCommonParams* cparams, LoadKernelParams* p) {
   }
 
   /* Show the dev mode warning screen */
-  VbDisplayScreen(cparams, VB_SCREEN_DEVELOPER_WARNING, 0);
+  VbDisplayScreen(cparams, VB_SCREEN_DEVELOPER_WARNING, 0, &vnc);
 
   /* Loop for dev mode warning delay */
   for (delay_time = 0; delay_time < delay_timeout;
@@ -490,7 +183,7 @@ VbError_t VbBootDeveloper(VbCommonParams* cparams, LoadKernelParams* p) {
         }
         break;
       default:
-        VbCheckDisplayKey(cparams, key);
+        VbCheckDisplayKey(cparams, key, &vnc);
         break;
         /* TODO: xyzzy easter egg check */
     }
@@ -527,19 +220,19 @@ VbError_t VbBootRecovery(VbCommonParams* cparams, LoadKernelParams* p) {
       VbExDiskFreeInfo(disk_info, NULL);
 
       if (0 == disk_count) {
-        VbDisplayScreen(cparams, VB_SCREEN_BLANK, 0);
+        VbDisplayScreen(cparams, VB_SCREEN_BLANK, 0, &vnc);
         break;
       }
 
       VBDEBUG(("VbBootRecovery() waiting for %d disks to be removed\n",
                (int)disk_count));
 
-      VbDisplayScreen(cparams, VB_SCREEN_RECOVERY_REMOVE, 0);
+      VbDisplayScreen(cparams, VB_SCREEN_RECOVERY_REMOVE, 0, &vnc);
 
       /* Scan keyboard more frequently than media, since x86 platforms
        * don't like to scan USB too rapidly. */
       for (i = 0; i < 4; i++) {
-        VbCheckDisplayKey(cparams, VbExKeyboardRead());
+        VbCheckDisplayKey(cparams, VbExKeyboardRead(), &vnc);
         if (VbExIsShutdownRequested())
           return VBERROR_SHUTDOWN_REQUESTED;
         VbExSleepMs(REC_DELAY_INCREMENT);
@@ -561,12 +254,13 @@ VbError_t VbBootRecovery(VbCommonParams* cparams, LoadKernelParams* p) {
       break;  /* Found a recovery kernel */
 
     VbDisplayScreen(cparams, VBERROR_NO_DISK_FOUND == retval ?
-                    VB_SCREEN_RECOVERY_INSERT : VB_SCREEN_RECOVERY_NO_GOOD, 0);
+                    VB_SCREEN_RECOVERY_INSERT : VB_SCREEN_RECOVERY_NO_GOOD,
+                    0, &vnc);
 
     /* Scan keyboard more frequently than media, since x86 platforms don't like
      * to scan USB too rapidly. */
     for (i = 0; i < 4; i++) {
-      VbCheckDisplayKey(cparams, VbExKeyboardRead());
+      VbCheckDisplayKey(cparams, VbExKeyboardRead(), &vnc);
       if (VbExIsShutdownRequested())
         return VBERROR_SHUTDOWN_REQUESTED;
       VbExSleepMs(REC_DELAY_INCREMENT);
@@ -648,12 +342,12 @@ VbError_t VbSelectAndLoadKernel(VbCommonParams* cparams,
     /* Recovery boot */
     p.boot_flags |= BOOT_FLAG_RECOVERY;
     retval = VbBootRecovery(cparams, &p);
-    VbDisplayScreen(cparams, VB_SCREEN_BLANK, 0);
+    VbDisplayScreen(cparams, VB_SCREEN_BLANK, 0, &vnc);
 
   } else if (p.boot_flags & BOOT_FLAG_DEVELOPER) {
     /* Developer boot */
     retval = VbBootDeveloper(cparams, &p);
-    VbDisplayScreen(cparams, VB_SCREEN_BLANK, 0);
+    VbDisplayScreen(cparams, VB_SCREEN_BLANK, 0, &vnc);
 
   } else {
     /* Normal boot */
diff --git a/firmware/lib/vboot_display.c b/firmware/lib/vboot_display.c
new file mode 100644
index 00000000..179bf7ba
--- /dev/null
+++ b/firmware/lib/vboot_display.c
@@ -0,0 +1,325 @@
+/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Display functions used in kernel selection.
+ */
+
+#include "gbb_header.h"
+#include "utility.h"
+#include "vboot_api.h"
+#include "vboot_common.h"
+#include "vboot_display.h"
+#include "vboot_nvstorage.h"
+
+static uint32_t disp_current_screen = VB_SCREEN_BLANK;
+static uint32_t disp_width = 0, disp_height = 0;
+
+
+/* Get the number of localizations in the GBB bitmap data. */
+static VbError_t VbGetLocalizationCount(VbCommonParams* cparams,
+                                        uint32_t* count) {
+  GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)cparams->gbb_data;
+  BmpBlockHeader* hdr;
+
+  /* Default to 0 on error */
+  *count = 0;
+
+  /* Make sure the bitmap data is inside the GBB and is non-zero in size */
+  if (0 == gbb->bmpfv_size ||
+      gbb->bmpfv_offset > cparams->gbb_size ||
+      gbb->bmpfv_offset + gbb->bmpfv_size > cparams->gbb_size) {
+    return VBERROR_INVALID_GBB;
+  }
+
+  /* Sanity-check the bitmap block header */
+  hdr = (BmpBlockHeader *)(((uint8_t*)gbb) + gbb->bmpfv_offset);
+  if ((0 != Memcmp(hdr->signature, BMPBLOCK_SIGNATURE,
+                   BMPBLOCK_SIGNATURE_SIZE)) ||
+      (hdr->major_version > BMPBLOCK_MAJOR_VERSION) ||
+      ((hdr->major_version == BMPBLOCK_MAJOR_VERSION) &&
+       (hdr->minor_version > BMPBLOCK_MINOR_VERSION))) {
+    return VBERROR_INVALID_BMPFV;
+  }
+
+  *count = hdr->number_of_localizations;
+  return VBERROR_SUCCESS;
+}
+
+
+
+/* Display a screen from the GBB. */
+VbError_t VbDisplayScreenFromGBB(VbCommonParams* cparams, uint32_t screen,
+                                 VbNvContext *vncptr) {
+  GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)cparams->gbb_data;
+  uint8_t* bmpfv = NULL;
+  uint8_t* fullimage = NULL;
+  BmpBlockHeader* hdr;
+  ScreenLayout* layout;
+  ImageInfo* image_info;
+  uint32_t screen_index;
+  uint32_t localization = 0;
+  VbError_t retval = VBERROR_UNKNOWN;  /* Assume error until proven ok */
+  uint32_t inoutsize;
+  uint32_t offset;
+  uint32_t i;
+
+  /* Make sure the bitmap data is inside the GBB and is non-zero in size */
+  if (0 == gbb->bmpfv_size ||
+      gbb->bmpfv_offset > cparams->gbb_size ||
+      gbb->bmpfv_offset + gbb->bmpfv_size > cparams->gbb_size) {
+    VBDEBUG(("VbDisplayScreenFromGBB(): invalid bmpfv offset/size\n"));
+    return VBERROR_INVALID_GBB;
+  }
+
+  /* Copy bitmap data from GBB into RAM for speed */
+  bmpfv = (uint8_t*)VbExMalloc(gbb->bmpfv_size);
+  Memcpy(bmpfv, ((uint8_t*)gbb) + gbb->bmpfv_offset, gbb->bmpfv_size);
+
+  /* Sanity-check the bitmap block header */
+  hdr = (BmpBlockHeader *)bmpfv;
+  if ((0 != Memcmp(hdr->signature, BMPBLOCK_SIGNATURE,
+                   BMPBLOCK_SIGNATURE_SIZE)) ||
+      (hdr->major_version > BMPBLOCK_MAJOR_VERSION) ||
+      ((hdr->major_version == BMPBLOCK_MAJOR_VERSION) &&
+       (hdr->minor_version > BMPBLOCK_MINOR_VERSION))) {
+    VBDEBUG(("VbDisplayScreenFromGBB(): invalid/too new bitmap header\n"));
+    retval = VBERROR_INVALID_BMPFV;
+    goto VbDisplayScreenFromGBB_exit;
+  }
+
+  /* Translate screen ID into index.  Note that not all screens are in the
+   * GBB. */
+  /* TODO: ensure screen IDs match indices?  Having this translation
+   * here is awful. */
+  switch (screen) {
+    case VB_SCREEN_DEVELOPER_WARNING:
+      screen_index = 0;
+      break;
+    case VB_SCREEN_RECOVERY_REMOVE:
+      screen_index = 1;
+      break;
+    case VB_SCREEN_RECOVERY_NO_GOOD:
+      screen_index = 2;
+      break;
+    case VB_SCREEN_RECOVERY_INSERT:
+      screen_index = 3;
+      break;
+    case VB_SCREEN_BLANK:
+    case VB_SCREEN_DEVELOPER_EGG:
+    default:
+      /* Screens which aren't in the GBB */
+      VBDEBUG(("VbDisplayScreenFromGBB(): screen %d not in the GBB\n",
+               (int)screen));
+      retval = VBERROR_INVALID_SCREEN_INDEX;
+      goto VbDisplayScreenFromGBB_exit;
+  }
+  if (screen_index >= hdr->number_of_screenlayouts) {
+    VBDEBUG(("VbDisplayScreenFromGBB(): screen %d index %d not in the GBB\n",
+             (int)screen, (int)screen_index));
+    retval = VBERROR_INVALID_SCREEN_INDEX;
+    goto VbDisplayScreenFromGBB_exit;
+  }
+
+  /* Clip localization to the number of localizations present in the GBB */
+  VbNvGet(vncptr, VBNV_LOCALIZATION_INDEX, &localization);
+  if (localization >= hdr->number_of_localizations) {
+    localization = 0;
+    VbNvSet(vncptr, VBNV_LOCALIZATION_INDEX, localization);
+  }
+
+  /* Calculate offset of screen layout = start of screen stuff +
+   * correct locale + correct screen. */
+  offset = sizeof(BmpBlockHeader) +
+      localization * hdr->number_of_screenlayouts * sizeof(ScreenLayout) +
+      screen_index * sizeof(ScreenLayout);
+  VBDEBUG(("VbDisplayScreenFromGBB(): scr_%d_%d at offset 0x%x\n",
+           localization, screen_index, offset));
+  layout = (ScreenLayout*)(bmpfv + offset);
+
+  /* Display all bitmaps for the image */
+  for (i = 0; i < MAX_IMAGE_IN_LAYOUT; i++) {
+    if (layout->images[i].image_info_offset) {
+      offset = layout->images[i].image_info_offset;
+      image_info = (ImageInfo*)(bmpfv + offset);
+      VBDEBUG(("VbDisplayScreenFromGBB: image %d: %dx%d+%d+%d %d/%d"
+               "tag %d at 0x%x\n",
+               i, image_info->width, image_info->height,
+               layout->images[i].x, layout->images[i].y,
+               image_info->compressed_size, image_info->original_size,
+               image_info->tag, offset));
+      if (COMPRESS_NONE != image_info->compression) {
+        inoutsize = image_info->original_size;
+        fullimage = (uint8_t*)VbExMalloc(inoutsize);
+        retval = VbExDecompress(bmpfv + offset + sizeof(ImageInfo),
+                                image_info->compressed_size,
+                                image_info->compression,
+                                fullimage, &inoutsize);
+        if (VBERROR_SUCCESS != retval) {
+          VbExFree(fullimage);
+          goto VbDisplayScreenFromGBB_exit;
+        }
+        retval = VbExDisplayImage(layout->images[i].x, layout->images[i].y,
+                                  fullimage, inoutsize);
+        VbExFree(fullimage);
+      } else {
+        retval = VbExDisplayImage(layout->images[i].x, layout->images[i].y,
+                                  bmpfv + offset + sizeof(ImageInfo),
+                                  image_info->original_size);
+      }
+      if (VBERROR_SUCCESS != retval)
+        goto VbDisplayScreenFromGBB_exit;
+    }
+  }
+
+  /* Successful if all bitmaps displayed */
+  retval = VBERROR_SUCCESS;
+
+VbDisplayScreenFromGBB_exit:
+
+  /* Free the bitmap data copy */
+  VbExFree(bmpfv);
+  return retval;
+}
+
+
+/* Display a screen, initializing the display if necessary.  If force!=0,
+ * redisplays the screen even if it's the same as the current screen. */
+VbError_t VbDisplayScreen(VbCommonParams* cparams, uint32_t screen, int force,
+                          VbNvContext *vncptr) {
+  VbError_t retval;
+
+  VBDEBUG(("VbDisplayScreen(%d, %d)\n", (int)screen, force));
+
+  /* Initialize display if necessary */
+  if (!disp_width) {
+    retval = VbExDisplayInit(&disp_width, &disp_height);
+    if (VBERROR_SUCCESS != retval)
+      return retval;
+  }
+
+  /* If the requested screen is the same as the current one, we're done. */
+  if (disp_current_screen == screen && 0 == force)
+    return VBERROR_SUCCESS;
+
+  /* If the screen is blank, turn off the backlight; else turn it on. */
+  VbExDisplayBacklight(VB_SCREEN_BLANK == screen ? 0 : 1);
+
+  /* Request the screen */
+  disp_current_screen = screen;
+
+  /* Look in the GBB first */
+  if (VBERROR_SUCCESS == VbDisplayScreenFromGBB(cparams, screen, vncptr))
+    return VBERROR_SUCCESS;
+
+  /* If the screen wasn't in the GBB bitmaps, fall back to a default screen. */
+  return VbExDisplayScreen(screen);
+}
+
+
+#define DEBUG_INFO_SIZE 512
+
+/* Display debug info to the screen */
+VbError_t VbDisplayDebugInfo(VbCommonParams* cparams, VbNvContext *vncptr) {
+  VbSharedDataHeader* shared = (VbSharedDataHeader*)cparams->shared_data_blob;
+  GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)cparams->gbb_data;
+  char buf[DEBUG_INFO_SIZE] = "";
+  uint32_t used = 0;
+  uint32_t i;
+
+  /* Redisplay the current screen, to overwrite any previous debug output */
+  VbDisplayScreen(cparams, disp_current_screen, 1, vncptr);
+
+  /* Add hardware ID */
+  used += Strncat(buf + used, "HWID: ", DEBUG_INFO_SIZE - used);
+  if (0 == gbb->hwid_size ||
+      gbb->hwid_offset > cparams->gbb_size ||
+      gbb->hwid_offset + gbb->hwid_size > cparams->gbb_size) {
+    VBDEBUG(("VbCheckDisplayKey(): invalid hwid offset/size\n"));
+    used += Strncat(buf + used, "(INVALID)", DEBUG_INFO_SIZE - used);
+  } else {
+    used += Strncat(buf + used, (char*)((uint8_t*)gbb + gbb->hwid_offset),
+                    DEBUG_INFO_SIZE - used);
+  }
+
+  /* Add recovery reason */
+  used += Strncat(buf + used, "\nrecovery_reason: 0x", DEBUG_INFO_SIZE - used);
+  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
+                         shared->recovery_reason, 16, 2);
+
+  /* Add VbSharedData flags */
+  used += Strncat(buf + used, "\nVbSD.flags: 0x", DEBUG_INFO_SIZE - used);
+  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
+                         shared->flags, 16, 8);
+
+  /* Add raw contents of VbNvStorage */
+  used += Strncat(buf + used, "\nVbNv.raw:", DEBUG_INFO_SIZE - used);
+  for (i = 0; i < VBNV_BLOCK_SIZE; i++) {
+    used += Strncat(buf + used, " ", DEBUG_INFO_SIZE - used);
+    used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
+                           vncptr->raw[i], 16, 2);
+  }
+
+  /* Add dev_boot_usb flag */
+  VbNvGet(vncptr, VBNV_DEV_BOOT_USB, &i);
+  used += Strncat(buf + used, "\ndev_boot_usb: ", DEBUG_INFO_SIZE - used);
+  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used, i, 10, 0);
+
+  /* Add TPM versions */
+  used += Strncat(buf + used, "\nTPM: fwver=0x", DEBUG_INFO_SIZE - used);
+  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
+                         shared->fw_version_tpm, 16, 8);
+  used += Strncat(buf + used, " kernver=0x", DEBUG_INFO_SIZE - used);
+  used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
+                         shared->kernel_version_tpm, 16, 8);
+
+  /* Add GBB flags */
+  used += Strncat(buf + used, "\ngbb.flags: 0x", DEBUG_INFO_SIZE - used);
+  if (gbb->major_version == GBB_MAJOR_VER && gbb->minor_version >= 1) {
+    used += Uint64ToString(buf + used, DEBUG_INFO_SIZE - used,
+                           gbb->flags, 16, 8);
+  } else {
+    used += Strncat(buf + used, "0 (default)", DEBUG_INFO_SIZE - used);
+  }
+
+  /* Make sure we finish with a newline */
+  used += Strncat(buf + used, "\n", DEBUG_INFO_SIZE - used);
+
+  /* TODO: add more interesting data:
+   * - SHA1 of kernel subkey (assuming we always set it in VbSelectFirmware,
+   *   even in recovery mode, where we just copy it from the root key)
+   * - Information on current disks */
+
+  buf[DEBUG_INFO_SIZE - 1] = '\0';
+  return VbExDisplayDebugInfo(buf);
+}
+
+
+VbError_t VbCheckDisplayKey(VbCommonParams* cparams, uint32_t key,
+                            VbNvContext *vncptr) {
+
+  if ('\t' == key) {
+    /* Tab = display debug info */
+    return VbDisplayDebugInfo(cparams, vncptr);
+
+  } else if (VB_KEY_LEFT == key || VB_KEY_RIGHT == key) {
+    /* Arrow keys = change localization */
+    uint32_t loc = 0;
+    uint32_t count = 0;
+
+    VbNvGet(vncptr, VBNV_LOCALIZATION_INDEX, &loc);
+    if (VBERROR_SUCCESS != VbGetLocalizationCount(cparams, &count))
+      loc = 0;  /* No localization count (bad GBB?), so set to 0 (default) */
+    else if (VB_KEY_RIGHT == key)
+      loc = (loc < count - 1 ? loc + 1 : 0);
+    else
+      loc = (loc > 0 ? loc - 1 : count - 1);
+    VBDEBUG(("VbCheckDisplayKey() - change localization to %d\n", (int)loc));
+    VbNvSet(vncptr, VBNV_LOCALIZATION_INDEX, loc);
+
+    /* Force redraw of current screen */
+    return VbDisplayScreen(cparams, disp_current_screen, 1, vncptr);
+  }
+
+  return VBERROR_SUCCESS;
+}