[PATCH v2 07/10] lib/fonts: Refactor glyph-rotation helpers

Thomas Zimmermann
2026-04-07T09:26:37Z

Change the signatures of the glyph-rotation helpers to match their
public interfaces. Drop the inline qualifier.

Rename several variables to better match their meaning. Especially
rename variables to bit_pitch (or a variant thereof) if they store
a pitch value in bits per scanline. The original code is fairly
confusing about this. Move the calculation of the bit pitch into the
new helper font_glyph_bit_pitch().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
lib/fonts/font_rotate.c | 85 ++++++++++++++++++++++++-----------------
1 file changed, 49 insertions(+), 36 deletions(-)

diff --git a/lib/fonts/font_rotate.c b/lib/fonts/font_rotate.c
index d79ec5eef712..09f6218e036f 100644
--- a/lib/fonts/font_rotate.c
+++ b/lib/fonts/font_rotate.c
@@ -15,6 +15,12 @@

#include "font.h"

+/* number of bits per line */
+static unsigned int font_glyph_bit_pitch(unsigned int width)
+{
+ return round_up(width, 8);
+}
+
static unsigned int __font_glyph_pos(unsigned int x, unsigned int y, unsigned int bit_pitch,
unsigned int *bit)
{
@@ -44,18 +50,21 @@ static void font_glyph_set_bit(unsigned char *glyph, unsigned int x, unsigned in
glyph[i] |= bit;
}

-static inline void rotate_cw(const char *in, char *out, u32 width, u32 height)
+static void __font_glyph_rotate_90(const unsigned char *glyph,
+ unsigned int width, unsigned int height,
+ unsigned char *out)
{
- int i, j, h = height, w = width;
- int shift = (8 - (height % 8)) & 7;
-
- width = (width + 7) & ~7;
- height = (height + 7) & ~7;
-
- for (i = 0; i < h; i++) {
- for (j = 0; j < w; j++) {
- if (font_glyph_test_bit(in, j, i, width))
- font_glyph_set_bit(out, height - 1 - i - shift, j, height);
+ unsigned int x, y;
+ unsigned int shift = (8 - (height % 8)) & 7;
+ unsigned int bit_pitch = font_glyph_bit_pitch(width);
+ unsigned int out_bit_pitch = font_glyph_bit_pitch(height);
+
+ for (y = 0; y < height; y++) {
+ for (x = 0; x < width; x++) {
+ if (font_glyph_test_bit(glyph, x, y, bit_pitch)) {
+ font_glyph_set_bit(out, out_bit_pitch - 1 - y - shift, x,
+ out_bit_pitch);
+ }
}
}
}
@@ -79,22 +88,24 @@ void font_glyph_rotate_90(const unsigned char *glyph, unsigned int width, unsign
{
memset(out, 0, font_glyph_size(height, width)); /* flip width/height */

- rotate_cw(glyph, out, width, height);
+ __font_glyph_rotate_90(glyph, width, height, out);
}
EXPORT_SYMBOL_GPL(font_glyph_rotate_90);

-static inline void rotate_ud(const char *in, char *out, u32 width, u32 height)
+static void __font_glyph_rotate_180(const unsigned char *glyph,
+ unsigned int width, unsigned int height,
+ unsigned char *out)
{
- int i, j;
- int shift = (8 - (width % 8)) & 7;
-
- width = (width + 7) & ~7;
-
- for (i = 0; i < height; i++) {
- for (j = 0; j < width - shift; j++) {
- if (font_glyph_test_bit(in, j, i, width))
- font_glyph_set_bit(out, width - (1 + j + shift),
- height - (1 + i), width);
+ unsigned int x, y;
+ unsigned int shift = (8 - (width % 8)) & 7;
+ unsigned int bit_pitch = font_glyph_bit_pitch(width);
+
+ for (y = 0; y < height; y++) {
+ for (x = 0; x < width; x++) {
+ if (font_glyph_test_bit(glyph, x, y, bit_pitch)) {
+ font_glyph_set_bit(out, width - (1 + x + shift), height - (1 + y),
+ bit_pitch);
+ }
}
}
}
@@ -115,22 +126,24 @@ void font_glyph_rotate_180(const unsigned char *glyph, unsigned int width, unsig
{
memset(out, 0, font_glyph_size(width, height));

- rotate_ud(glyph, out, width, height);
+ __font_glyph_rotate_180(glyph, width, height, out);
}
EXPORT_SYMBOL_GPL(font_glyph_rotate_180);

-static inline void rotate_ccw(const char *in, char *out, u32 width, u32 height)
+static void __font_glyph_rotate_270(const unsigned char *glyph,
+ unsigned int width, unsigned int height,
+ unsigned char *out)
{
- int i, j, h = height, w = width;
- int shift = (8 - (width % 8)) & 7;
-
- width = (width + 7) & ~7;
- height = (height + 7) & ~7;
-
- for (i = 0; i < h; i++) {
- for (j = 0; j < w; j++) {
- if (font_glyph_test_bit(in, j, i, width))
- font_glyph_set_bit(out, i, width - 1 - j - shift, height);
+ unsigned int x, y;
+ unsigned int shift = (8 - (width % 8)) & 7;
+ unsigned int bit_pitch = font_glyph_bit_pitch(width);
+ unsigned int out_bit_pitch = font_glyph_bit_pitch(height);
+
+ for (y = 0; y < height; y++) {
+ for (x = 0; x < width; x++) {
+ if (font_glyph_test_bit(glyph, x, y, bit_pitch))
+ font_glyph_set_bit(out, y, bit_pitch - 1 - x - shift,
+ out_bit_pitch);
}
}
}
@@ -154,6 +167,6 @@ void font_glyph_rotate_270(const unsigned char *glyph, unsigned int width, unsig
{
memset(out, 0, font_glyph_size(height, width)); /* flip width/height */

- rotate_ccw(glyph, out, width, height);
+ __font_glyph_rotate_270(glyph, width, height, out);
}
EXPORT_SYMBOL_GPL(font_glyph_rotate_270);
--
2.53.0