diff options
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/vt/vt.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 49a140b49eff..8415e274e4be 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -71,6 +71,7 @@ * by Adam Tla/lka <atlka@pg.gda.pl>, Aug 2006 */ +#include <linux/compiler.h> #include <linux/module.h> #include <linux/types.h> #include <linux/sched/signal.h> @@ -265,6 +266,119 @@ unsigned int vc_font_size(const struct vc_font *font) EXPORT_SYMBOL_GPL(vc_font_size); /* + * Cursors + */ + +/** + * vc_cursor_valid_size - Computes a valid cursor size from the given value + * @cursor_size: The size constant of cursor pattern + * + * The argument given in @cursor_size is one of the CUR_ constants, as stored + * in struct @vc_data.vc_cursor_type. For unknown values, the helper draws the + * default cursor or an underline dash. + * + * Returns: + * A valid cursor size for the given size value + */ +unsigned int vc_cursor_valid_size(unsigned int cursor_size) +{ + const unsigned int cursor_default_size = CUR_SIZE(READ_ONCE(cur_default)); + + do { + switch (cursor_size) { + case CUR_NONE: + case CUR_UNDERLINE: + case CUR_LOWER_THIRD: + case CUR_LOWER_HALF: + case CUR_TWO_THIRDS: + case CUR_BLOCK: + return cursor_size; + default: + pr_warn_once("Unknown cursor %u\n", cursor_size); + fallthrough; + case CUR_DEF: + /* + * Use user-given default size, or underline if + * the given default is invalid. + */ + if (cursor_size != cursor_default_size) + cursor_size = cursor_default_size; + else + cursor_size = CUR_UNDERLINE; + } + } while (true); +} +EXPORT_SYMBOL_GPL(vc_cursor_valid_size); + +/** + * vc_cursor_start - Calculates the cursor's first scanline within a character cell + * @cell_height: The overall height of the character cell + * @cursor_size: The size constant of cursor pattern + * + * The parameter @cell_height is the height of the character cell as + * displayed by the console. The argument given in @cursor_size is one + * of the CUR_ constants. See vc_cursor_valid_size() for how to get a + * valid cursor-size constant. + * + * Returns: + * The index of the cursor's first scanline within the character cell + */ +unsigned int vc_cursor_start(unsigned int cell_height, unsigned int cursor_size) +{ + switch (cursor_size) { + case CUR_NONE: + return cell_height; + case CUR_UNDERLINE: + default: + if (cell_height < 10) + return cell_height - 1; + else + return cell_height - 3; + case CUR_LOWER_THIRD: + return cell_height - cell_height / 3; + case CUR_LOWER_HALF: + return cell_height - cell_height / 2; + case CUR_TWO_THIRDS: + return cell_height - (cell_height * 2) / 3; + case CUR_BLOCK: + return 0; + } +} +EXPORT_SYMBOL_GPL(vc_cursor_start); + +/** + * vc_cursor_end - Calculates the first scanline after the cursor within a character cell + * @cell_height: The overall height of the character cell + * @cursor_size: The size constant of cursor pattern + * + * The parameter @cell_height is the height of the character cell as + * displayed by the console. The argument given in @cursor_size is one + * of the CUR_ constants. See vc_cursor_valid_size() for how to get a + * valid cursor-size constant. + * + * Returns: + * The index of the first scanline after the cursor within the character cell + */ +unsigned int vc_cursor_end(unsigned int cell_height, unsigned int cursor_size) +{ + switch (cursor_size) { + case CUR_UNDERLINE: + default: + if (cell_height < 10) + return cell_height; + else + return cell_height - 1; + case CUR_NONE: + case CUR_LOWER_THIRD: + case CUR_LOWER_HALF: + case CUR_TWO_THIRDS: + case CUR_BLOCK: + return cell_height; + } +} +EXPORT_SYMBOL_GPL(vc_cursor_end); + +/* * /sys/class/tty/tty0/ * * the attribute 'active' contains the name of the current vc |