diff options
| -rw-r--r-- | Makefile | 1 | ||||
| -rw-r--r-- | common.h | 1 | ||||
| -rw-r--r-- | libfonts.h | 85 | ||||
| -rw-r--r-- | libfonts_create_transcoding_table.c | 124 |
4 files changed, 210 insertions, 1 deletions
@@ -19,6 +19,7 @@ LIB_NAME = fonts PUBLIC_OBJ =\ libfonts_calculate_subpixel_order.o\ libfonts_char_is_in_subset.o\ + libfonts_create_transcoding_table.o\ libfonts_deallocate_encoding.o\ libfonts_deallocate_encoding_mapping.o\ libfonts_deallocate_encoding_mapping_entry.o\ @@ -7,6 +7,7 @@ #include <limits.h> #include <pwd.h> #include <stdarg.h> +#include <stddef.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> @@ -13,6 +13,13 @@ #define LIBFONTS_CONTEXT_VERSION 0 /** + * Target character index used to signify that the + * source character index is invalid or has not + * mapping to the target encoding + */ +#define LIBFONTS_UNDEFINED_CHAR (UINT32_C(0xFFFFFFFF)) + +/** * File name of file in font directories that is used * to create font aliases */ @@ -1866,7 +1873,6 @@ struct libfonts_encoding { * List of coded translation mappings */ struct libfonts_encoding_mapping *mappings; - /* TODO add functions for creating tables in either direction */ /** * The number of elements in `.mappings` @@ -1903,6 +1909,65 @@ struct libfonts_encoding { /** + * Lookup table for translating from one + * text encoding into another + */ +struct libfonts_transcoding_table { + /** + * Source character indices lower than + * this value should be rejected without + * looking in `.table` + */ + uint32_t first_valid; + + /** + * Source character indices higher than + * this value should be rejected without + * looking in `.table` + */ + uint32_t last_valid; + + /** + * See `.table` + */ + uint32_t offset; + + /** + * See `.table` + * + * If this value is 0, the source encoding uses one byte + * per character, otherwise it uses two bytes per character + */ + uint32_t multiplier; + + /** + * For a source character index `i`, the target character index is + * `.table[((i - .offset) >> 8) * .multiplier + ((i - .offset) & 0xFF)]` + * (`LIBFONTS_LOOKUP_TRANSCODING_TABLE` performs this lookup); + * however, if this value is `LIBFONTS_UNDEFINED_CHAR`, the + * character has no mapping: either `i` is an invalid character + * index in the source encoding, or the corresponding character + * does not exist in the target encoding + */ + uint32_t table[]; +}; + + +/** + * Converts a source character index to a target character index + * via a transcoding table + * + * @param TABLE:const struct libfonts_transcoding_table * The transcoding table + * @param I:uint32_t The source character index + * @return :uint32_t The target character index, or + * `LIBFONTS_UNDEFINED_CHAR` if there is no mapping + */ +#define LIBFONTS_LOOKUP_TRANSCODING_TABLE(TABLE, I)\ + ((TABLE)->table[(((uint32_t)(I) - (TABLE)->offset) >> 8) * (TABLE)->multiplier +\ + (((uint32_t)(I) - (TABLE)->offset) & 0xFF)]) + + +/** * Structure that can be used to spoof the * environment the library is executed in, * as well as the print warnings from the @@ -2158,6 +2223,24 @@ void libfonts_deallocate_encoding(struct libfonts_encoding *); */ int libfonts_parse_encoding_line(struct libfonts_encoding **, int *, const char *, char **, struct libfonts_context *); +/** + * Create a transcoding table + * + * @param encoding The source encoding + * @param mapping The index in `encoding->mappings` for the target encoding + * @return Transcoding table, deallocatable with free(3), or `NULL` on failure + * + * @throws ENOMEM Failed to allocate enough memory + * @throws EINVAL `encoding` is `NULL` + * @throws EINVAL `mapping` is equal to or greater than `encoding->nmappings` + * @throws EINVAL The contents of `encoding` is invalid + * @throws EINVAL One of the entries in the mapping has the + * `LIBFONTS_ENCODING_MAPPING_ENTRY_INDEX_TO_NAME` type + */ +struct libfonts_transcoding_table *libfonts_create_transcoding_table(const struct libfonts_encoding *, size_t); + +/* TODO add libfonts_create_reverse_transcoding_table */ + /** * Get the font a default font name aliases to diff --git a/libfonts_create_transcoding_table.c b/libfonts_create_transcoding_table.c new file mode 100644 index 0000000..ee75bf4 --- /dev/null +++ b/libfonts_create_transcoding_table.c @@ -0,0 +1,124 @@ +/* See LICENSE file for copyright and license details. */ +#include "common.h" +#ifndef TEST + + +static int +set_range(uint32_t low, uint32_t high, uint32_t target, uint32_t target_inc, struct libfonts_transcoding_table *table) +{ + uint32_t i; + + if (low < table->first_valid) { + if (target != LIBFONTS_UNDEFINED_CHAR) + return -1; + low = table->first_valid; + } + + if (high > table->last_valid) { + if (target != LIBFONTS_UNDEFINED_CHAR) + return -1; + high = table->last_valid; + } + + i = low; + do { + LIBFONTS_LOOKUP_TRANSCODING_TABLE(table, i) = target; + target += target_inc; + } while (i++ < high); + + return 0; +} + +struct libfonts_transcoding_table * +libfonts_create_transcoding_table(const struct libfonts_encoding *encoding, size_t mapping) +{ + const struct libfonts_encoding_mapping *map; + size_t size, entry; + uint16_t size_rows, size_cols; + uint8_t first_row, first_col; + struct libfonts_transcoding_table *ret; + uint32_t i; + int r; + + if (!encoding || + mapping > encoding->nmappings || + !encoding->mappings || + (encoding->mappings[mapping].nentries && !encoding->mappings[mapping].entries) || + !encoding->size_rows) + goto einvalid; + + map = &encoding->mappings[mapping]; + size_rows = encoding->size_rows; + size_cols = encoding->size_cols; + first_row = encoding->first_index_row; + first_col = encoding->first_index_col; + +#if SIZE_MAX <= UINT32_MAX + if ((size_t)size_rows - (size_t)first_row > SIZE_MAX / (size_cols ? (size_t)size_cols : 1)) + goto enomem; +#endif + size = ((size_t)size_rows - (size_t)first_row) * (size_cols ? (size_t)size_cols : 1); + if (size > (SIZE_MAX - offsetof(struct libfonts_transcoding_table, table)) / sizeof(uint32_t)) + goto enomem; + ret = malloc(size * sizeof(uint32_t) + offsetof(struct libfonts_transcoding_table, table)); + if (!ret) + goto enomem; + + ret->first_valid = (uint32_t)first_row; + ret->last_valid = (uint32_t)size_rows - 1; + if (size_cols) { + ret->first_valid <<= 8; + ret->first_valid |= (uint32_t)first_col; + ret->last_valid <<= 8; + ret->last_valid |= (uint32_t)size_cols - 1; + } + + ret->offset = encoding->size_cols ? (uint32_t)first_row << 8 : (uint32_t)first_col; + ret->multiplier = (uint32_t)size_cols; + + for (i = ret->first_valid; i <= ret->last_valid; i++) + LIBFONTS_LOOKUP_TRANSCODING_TABLE(ret, i) = i; + + for (entry = 0; entry < map->nentries; entry++) { + if (map->entries[entry].type == LIBFONTS_ENCODING_MAPPING_ENTRY_UNDEFINED_RANGE) { + set_range(map->entries[entry].undefined_range.low_source, + map->entries[entry].undefined_range.high_source, + LIBFONTS_UNDEFINED_CHAR, 0, ret); + + } else if (map->entries[entry].type == LIBFONTS_ENCODING_MAPPING_ENTRY_REMAPPED_RANGE) { + r = set_range(map->entries[entry].remapped_range.low_source, + map->entries[entry].remapped_range.high_source, + map->entries[entry].remapped_range.low_target, 0, ret); + if (r) + goto invalid; + + } else { + goto invalid; + } + } + + return ret; + +enomem: + errno = ENOMEM; + return NULL; + +invalid: + free(ret); +einvalid: + errno = EINVAL; + return NULL; +} + + +#else + + +int +main(void) +{ + return 0; /* XXX add test */ +} + + +#endif |