From 03c9cdf71d25fcc7ccd5e896e51f6795264c19db Mon Sep 17 00:00:00 2001
From: Toomas Soome <tsoome@FreeBSD.org>
Date: Sun, 6 Oct 2019 18:38:58 +0000
Subject: [PATCH] loader.efi: for text mode, use STM to scroll the whole screen

Since local UEFI console is implemented on top of framebuffer,
we need to avoid redrawing the whole screen ourselves, but let
Simple Text Mode to do the scroll for us.
---
 stand/efi/libefi/efi_console.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/stand/efi/libefi/efi_console.c b/stand/efi/libefi/efi_console.c
index 26e051fe73a..99c891b2125 100644
--- a/stand/efi/libefi/efi_console.c
+++ b/stand/efi/libefi/efi_console.c
@@ -136,7 +136,7 @@ efi_text_cursor(void *s __unused, const teken_pos_t *p)
 }
 
 static void
-efi_text_printchar(const teken_pos_t *p)
+efi_text_printchar(const teken_pos_t *p, bool autoscroll)
 {
 	UINTN a, attr;
 	struct text_pixel *px;
@@ -164,7 +164,8 @@ efi_text_printchar(const teken_pos_t *p)
 	conout->SetCursorPosition(conout, p->tp_col, p->tp_row);
 
 	/* to prvent autoscroll, skip print of lower right char */
-	if (p->tp_row == tp.tp_row - 1 &&
+	if (!autoscroll &&
+	    p->tp_row == tp.tp_row - 1 &&
 	    p->tp_col == tp.tp_col - 1)
 		return;
 
@@ -183,7 +184,7 @@ efi_text_putchar(void *s __unused, const teken_pos_t *p, teken_char_t c,
 	idx = p->tp_col + p->tp_row * tp.tp_col;
 	buffer[idx].c = c;
 	buffer[idx].a = *a;
-	efi_text_printchar(p);
+	efi_text_printchar(p, false);
 }
 
 static void
@@ -226,6 +227,7 @@ efi_text_copy(void *ptr __unused, const teken_rect_t *r, const teken_pos_t *p)
 	int srow, drow;
 	int nrow, ncol, x, y; /* Has to be signed - >= 0 comparison */
 	teken_pos_t d, s;
+	bool scroll = false;
 
 	/*
 	 * Copying is a little tricky. We must make sure we do it in
@@ -235,6 +237,13 @@ efi_text_copy(void *ptr __unused, const teken_rect_t *r, const teken_pos_t *p)
 	nrow = r->tr_end.tp_row - r->tr_begin.tp_row;
 	ncol = r->tr_end.tp_col - r->tr_begin.tp_col;
 
+	/*
+	 * Check if we do copy whole screen.
+	 */
+	if (p->tp_row == 0 && p->tp_col == 0 &&
+	    nrow == tp.tp_row - 2 && ncol == tp.tp_col - 2)
+		scroll = true;
+
 	conout->EnableCursor(conout, FALSE);
 	if (p->tp_row < r->tr_begin.tp_row) {
 		/* Copy from bottom to top. */
@@ -252,7 +261,17 @@ efi_text_copy(void *ptr __unused, const teken_rect_t *r, const teken_pos_t *p)
 				    &buffer[s.tp_col + srow])) {
 					buffer[d.tp_col + drow] =
 					    buffer[s.tp_col + srow];
-					efi_text_printchar(&d);
+					if (!scroll)
+						efi_text_printchar(&d, false);
+				} else if (scroll) {
+					/*
+					 * Draw last char and trigger
+					 * scroll.
+					 */
+					if (y == nrow - 1 &&
+					    x == ncol - 1) {
+						efi_text_printchar(&d, true);
+					}
 				}
 			}
 		}
@@ -274,7 +293,7 @@ efi_text_copy(void *ptr __unused, const teken_rect_t *r, const teken_pos_t *p)
 					    &buffer[s.tp_col + srow])) {
 						buffer[d.tp_col + drow] =
 						    buffer[s.tp_col + srow];
-						efi_text_printchar(&d);
+						efi_text_printchar(&d, false);
 					}
 				}
 			}
@@ -294,7 +313,7 @@ efi_text_copy(void *ptr __unused, const teken_rect_t *r, const teken_pos_t *p)
 					    &buffer[s.tp_col + srow])) {
 						buffer[d.tp_col + drow] =
 						    buffer[s.tp_col + srow];
-						efi_text_printchar(&d);
+						efi_text_printchar(&d, false);
 					}
 				}
 			}