From 98a6cabfd805d55a1b2c70b01923ec9b9bbc706a Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Fri, 29 May 2026 16:01:23 +0200 Subject: lib/fonts: Look up glyph data with font_data_glyph_buf() Add font_data_glyph_buf() to retrieve a character's glyph data or NULL otherwise. Console fonts can currently contain 256 or 512 glyphs. The kernel-internal characters are of type char, unsigned short or unsigned int. Catch all of them by accepting unsigned int. Callers possibly have to cast from signed to unsigned types to reach all glyphs in a font. Signed-off-by: Thomas Zimmermann Reviewed-by: Jocelyn Falempe Link: https://patch.msgid.link/20260529140759.529929-2-tzimmermann@suse.de --- lib/fonts/fonts.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'lib') diff --git a/lib/fonts/fonts.c b/lib/fonts/fonts.c index f5d5333450a0..4fc66722d00d 100644 --- a/lib/fonts/fonts.c +++ b/lib/fonts/fonts.c @@ -178,6 +178,37 @@ unsigned int font_data_size(font_data_t *fd) } EXPORT_SYMBOL_GPL(font_data_size); +static unsigned int font_data_num_glyphs(font_data_t *fd, unsigned int width, unsigned int height) +{ + return font_data_size(fd) / font_glyph_size(width, height); +} + +/** + * font_data_glyph_buf() - Returns the glyph for a specific character as raw bytes + * @fd: The font data + * @width: The glyph width in bits per scanline + * @vpitch: The number of scanlines per glyph + * @c: The character + * + * Glyphs start at fixed intervals within the font data. font_data_glyph_buf() + * returns the glyph shape of the specified character. If no such glyph + * exists in the font, it returns NULL. + * + * Returns: + * The character's raw glyph shape, or NULL if no glyph exists for the character. The + * provided buffer is read-only. + */ +const unsigned char *font_data_glyph_buf(font_data_t *fd, + unsigned int width, unsigned int vpitch, + unsigned int c) +{ + if (c >= font_data_num_glyphs(fd, width, vpitch)) + return NULL; + + return font_data_buf(fd) + font_glyph_size(width, vpitch) * c; +} +EXPORT_SYMBOL_GPL(font_data_glyph_buf); + /** * font_data_is_equal - Compares font data for equality * @lhs: Left-hand side font data -- cgit