diff options
| -rw-r--r-- | drivers/tty/vt/Makefile | 3 | ||||
| -rw-r--r-- | drivers/tty/vt/ucs.c | 84 | ||||
| -rw-r--r-- | include/linux/consolemap.h | 6 |
3 files changed, 92 insertions, 1 deletions
diff --git a/drivers/tty/vt/Makefile b/drivers/tty/vt/Makefile index 509362a3e11e..ae746dcdeec8 100644 --- a/drivers/tty/vt/Makefile +++ b/drivers/tty/vt/Makefile @@ -36,7 +36,8 @@ $(obj)/defkeymap.c: $(obj)/%.c: $(src)/%.map endif -$(obj)/ucs.o: $(src)/ucs.c $(obj)/ucs_width_table.h $(obj)/ucs_recompose_table.h +$(obj)/ucs.o: $(src)/ucs.c $(obj)/ucs_width_table.h \ + $(obj)/ucs_recompose_table.h $(obj)/ucs_fallback_table.h # You may uncomment one of those to have the UCS tables be regenerated # during the build process. By default the _shipped versions are used. diff --git a/drivers/tty/vt/ucs.c b/drivers/tty/vt/ucs.c index b0b23830170d..6c15c5deda5b 100644 --- a/drivers/tty/vt/ucs.c +++ b/drivers/tty/vt/ucs.c @@ -157,3 +157,87 @@ u32 ucs_recompose(u32 base, u32 mark) return result ? result->recomposed : 0; } + +/* + * The fallback table structures implement a 2-level lookup. + */ + +struct ucs_page_desc { + u8 page; /* Page index (high byte of code points) */ + u8 count; /* Number of entries in this page */ + u16 start; /* Start index in entries array */ +}; + +struct ucs_page_entry { + u8 offset; /* Offset within page (0-255) */ + u8 fallback; /* Fallback character or range start marker */ +}; + +#include "ucs_fallback_table.h" + +static int ucs_page_desc_cmp(const void *key, const void *element) +{ + u8 page = *(u8 *)key; + const struct ucs_page_desc *entry = element; + + if (page < entry->page) + return -1; + if (page > entry->page) + return 1; + return 0; +} + +static int ucs_page_entry_cmp(const void *key, const void *element) +{ + u8 offset = *(u8 *)key; + const struct ucs_page_entry *entry = element; + + if (offset < entry->offset) + return -1; + if (entry->fallback == UCS_PAGE_ENTRY_RANGE_MARKER) { + if (offset > entry[1].offset) + return 1; + } else { + if (offset > entry->offset) + return 1; + } + return 0; +} + +/** + * ucs_get_fallback() - Get a substitution for the provided Unicode character + * @base: Base Unicode code point (UCS-4) + * + * Get a simpler fallback character for the provided Unicode character. + * This is used for terminal display when corresponding glyph is unavailable. + * The substitution may not be as good as the actual glyph for the original + * character but still way more helpful than a squared question mark. + * + * Return: Fallback Unicode code point, or 0 if none is available + */ +u32 ucs_get_fallback(u32 cp) +{ + const struct ucs_page_desc *page; + const struct ucs_page_entry *entry; + u8 page_idx = cp >> 8, offset = cp; + + if (!UCS_IS_BMP(cp)) + return 0; + + page = __inline_bsearch(&page_idx, ucs_fallback_pages, + ARRAY_SIZE(ucs_fallback_pages), + sizeof(*ucs_fallback_pages), + ucs_page_desc_cmp); + if (!page) + return 0; + + entry = __inline_bsearch(&offset, ucs_fallback_entries + page->start, + page->count, sizeof(*ucs_fallback_entries), + ucs_page_entry_cmp); + if (!entry) + return 0; + + if (entry->fallback == UCS_PAGE_ENTRY_RANGE_MARKER) + entry++; + return entry->fallback; +} diff --git a/include/linux/consolemap.h b/include/linux/consolemap.h index 8167494229db..6180b803795c 100644 --- a/include/linux/consolemap.h +++ b/include/linux/consolemap.h @@ -31,6 +31,7 @@ void console_map_init(void); bool ucs_is_double_width(uint32_t cp); bool ucs_is_zero_width(uint32_t cp); u32 ucs_recompose(u32 base, u32 mark); +u32 ucs_get_fallback(u32 cp); #else static inline u16 inverse_translate(const struct vc_data *conp, u16 glyph, bool use_unicode) @@ -75,6 +76,11 @@ static inline u32 ucs_recompose(u32 base, u32 mark) { return 0; } + +static inline u32 ucs_get_fallback(u32 cp) +{ + return 0; +} #endif /* CONFIG_CONSOLE_TRANSLATIONS */ #endif /* __LINUX_CONSOLEMAP_H__ */ |