lib/tatables.c

   1 /* tatables.c */
   2
   3 /*
   4  * Copyright (C) 2011-2012 by Werner Lemberg.
   5  *
   6  * This file is part of the ttfautohint library, and may only be used,
   7  * modified, and distributed under the terms given in `COPYING'.  By
   8  * continuing to use, modify, or distribute this file you indicate that you
   9  * have read `COPYING' and understand and accept it fully.
  10  *
  11  * The file `COPYING' mentioned in the previous paragraph is distributed
  12  * with the ttfautohint library.
  13  */
  14
  15
  16 #include <stdlib.h>
  17
  18 #include "ta.h"
  19
  20
  21 FT_Error
  22 TA_sfnt_add_table_info(SFNT* sfnt)
  23 {
  24   SFNT_Table_Info* table_infos_new;
  25
  26
  27   sfnt->num_table_infos++;
  28   table_infos_new =
  29     (SFNT_Table_Info*)realloc(sfnt->table_infos, sfnt->num_table_infos
  30                                                  * sizeof (SFNT_Table_Info));
  31   if (!table_infos_new)
  32   {
  33     sfnt->num_table_infos--;
  34     return FT_Err_Out_Of_Memory;
  35   }
  36   else
  37     sfnt->table_infos = table_infos_new;
  38
  39   sfnt->table_infos[sfnt->num_table_infos - 1] = MISSING;
  40
  41   return TA_Err_Ok;
  42 }
  43
  44
  45 FT_ULong
  46 TA_table_compute_checksum(FT_Byte* buf,
  47                           FT_ULong len)
  48 {
  49   FT_Byte* end_buf = buf + len;
  50   FT_ULong checksum = 0;
  51
  52
  53   /* we expect that the length of `buf' is a multiple of 4 */
  54
  55   while (buf < end_buf)
  56   {
  57     checksum += *(buf++) << 24;
  58     checksum += *(buf++) << 16;
  59     checksum += *(buf++) << 8;
  60     checksum += *(buf++);
  61   }
  62
  63   return checksum;
  64 }
  65
  66
  67 FT_Error
  68 TA_font_add_table(FONT* font,
  69                   SFNT_Table_Info* table_info,
  70                   FT_ULong tag,
  71                   FT_ULong len,
  72                   FT_Byte* buf)
  73 {
  74   SFNT_Table* tables_new;
  75   SFNT_Table* table_last;
  76
  77
  78   font->num_tables++;
  79   tables_new = (SFNT_Table*)realloc(font->tables,
  80                                     font->num_tables * sizeof (SFNT_Table));
  81   if (!tables_new)
  82   {
  83     font->num_tables--;
  84     return FT_Err_Out_Of_Memory;
  85   }
  86   else
  87     font->tables = tables_new;
  88
  89   table_last = &font->tables[font->num_tables - 1];
  90
  91   table_last->tag = tag;
  92   table_last->len = len;
  93   table_last->buf = buf;
  94   table_last->checksum = TA_table_compute_checksum(buf, len);
  95   table_last->offset = 0; /* set in `TA_font_compute_table_offsets' */
  96   table_last->data = NULL;
  97   table_last->processed = 0;
  98
  99   /* link table and table info */
 100   *table_info = font->num_tables - 1;
 101
 102   return TA_Err_Ok;
 103 }
 104
 105
 106 void
 107 TA_sfnt_sort_table_info(SFNT* sfnt,
 108                         FONT* font)
 109 {
 110   /* Looking into an arbitrary TTF (with a `DSIG' table), tags */
 111   /* starting with an uppercase letter are sorted before lowercase */
 112   /* letters.  In other words, the alphabetical ordering (as */
 113   /* mandated by signing a font) is a simple numeric comparison of */
 114   /* the 32bit tag values. */
 115
 116   SFNT_Table* tables = font->tables;
 117
 118   SFNT_Table_Info* table_infos = sfnt->table_infos;
 119   FT_ULong num_table_infos = sfnt->num_table_infos;
 120
 121   FT_ULong i;
 122   FT_ULong j;
 123
 124
 125   /* bubble sort */
 126   for (i = 1; i < num_table_infos; i++)
 127   {
 128     for (j = i; j > 0; j--)
 129     {
 130       SFNT_Table_Info swap;
 131       FT_ULong tag1;
 132       FT_ULong tag2;
 133
 134
 135       tag1 = (table_infos[j] == MISSING)
 136                ? 0
 137                : tables[table_infos[j]].tag;
 138       tag2 = (table_infos[j - 1] == MISSING)
 139                ? 0
 140                : tables[table_infos[j - 1]].tag;
 141
 142       if (tag1 > tag2)
 143         break;
 144
 145       swap = table_infos[j];
 146       table_infos[j] = table_infos[j - 1];
 147       table_infos[j - 1] = swap;
 148     }
 149   }
 150 }
 151
 152
 153 void
 154 TA_font_compute_table_offsets(FONT* font,
 155                               FT_ULong start)
 156 {
 157   FT_ULong i;
 158   FT_ULong offset = start;
 159
 160
 161   for (i = 0; i < font->num_tables; i++)
 162   {
 163     SFNT_Table* table = &font->tables[i];
 164
 165
 166     table->offset = offset;
 167
 168     /* table offsets must be multiples of 4; */
 169     /* this also fits the actual buffer lengths */
 170     offset += (table->len + 3) & ~3;
 171   }
 172 }
 173
 174 /* end of tatables.c */