[S] Change in coreboot[master]: drivers/pc80/vga: display a string centered on a line

[Jérémy Compostella (Code Review)]

Jérémy Compostella has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/70277 )

Change subject: drivers/pc80/vga: display a string centered on a line
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drivers/pc80/vga: display a string centered on a line

This patch introduces the `vga_line_write_centered(unsigned int line,
const char *string)' function to display a centered line of text. The
string length is limited to eighy characters.

BUG=b:252792591
BRANCH=firmware-brya-14505.B
TEST=TO-BE-COMPLETED

Change-Id: Ie742795bb44bbea8cf24222e7bd4f355a6fece2f
Signed-off-by: Jeremy Compostella 
---
M src/drivers/pc80/vga/vga.c
M src/include/pc80/vga.h
2 files changed, 41 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/77/70277/1

diff --git a/src/drivers/pc80/vga/vga.c b/src/drivers/pc80/vga/vga.c
index d970fea..1719cba 100644
--- a/src/drivers/pc80/vga/vga.c
+++ b/src/drivers/pc80/vga/vga.c
@@ -274,6 +274,28 @@
 }

/*
+ * fills a line centering the given string.
+ * The string is truncated it exceeds 80 characters.
+ */
+void
+vga_line_write_centered(unsigned int line, const char *string)
+{
+	unsigned short *p = (unsigned short *) VGA_FB + (80 * line);
+	size_t i, margin, len = strlen(string);
+
+	if (len > 80)
+		len = 80;
+	margin = 40 - (len / 2);
+
+	for (i = 0; i < 80; i++) {
+		if (i < margin || i > 80 - margin)
+			p[i] = 0x0F00;
+		else
+			p[i] = 0x0F00 | string[i - margin];
+	}
+}
+
+/*
  * set up everything to get a basic 80x25 textmode.
  */
 void
diff --git a/src/include/pc80/vga.h b/src/include/pc80/vga.h
index 4b7b26c..9e72f6f 100644
--- a/src/include/pc80/vga.h
+++ b/src/include/pc80/vga.h
@@ -19,5 +19,6 @@
 void vga_frame_set(unsigned int line, unsigned int character);

void vga_line_write(unsigned int line, const char *string);
+void vga_line_write_centered(unsigned int line, const char *string);

#endif /* VGA_H */