src/taprep.c

   1 /* taprep.c */
   2
   3 /*
   4  * Copyright (C) 2011 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 "ta.h"
  17
  18
  19 #define PREP(snippet_name) prep_ ## snippet_name
  20
  21 /* we often need 0x10000 which can't be pushed directly onto the stack, */
  22 /* thus we provide it in the CVS as `cvtl_0x10000'; */
  23 /* at the same time, we store it in CVT index `cvtl_funits_to_pixels' also */
  24 /* as a scaled value to have a conversion factor from FUnits to pixels */
  25
  26 unsigned char PREP(store_0x10000) [] = {
  27
  28   PUSHW_2,
  29     0x08, /* 0x800 */
  30     0x00,
  31     0x08, /* 0x800 */
  32     0x00,
  33   MUL, /* 0x10000 */
  34
  35   DUP,
  36   PUSHB_1,
  37     cvtl_0x10000,
  38   SWAP,
  39   WCVTP,
  40
  41   DUP,
  42   PUSHB_1,
  43     cvtl_funits_to_pixels,
  44   SWAP,
  45   WCVTF, /* store value 1 in 16.16 format, scaled */
  46
  47 };
  48
  49 unsigned char PREP(align_top_a) [] = {
  50
  51   /* optimize the alignment of the top of small letters to the pixel grid */
  52
  53   PUSHB_1,
  54
  55 };
  56
  57 /*  %c, index of alignment blue zone */
  58
  59 unsigned char PREP(align_top_b) [] = {
  60
  61   RCVT,
  62   DUP,
  63   DUP,
  64   PUSHB_1,
  65     40,
  66   ADD,
  67   FLOOR, /* fitted = FLOOR(scaled + 40) */
  68   DUP, /* s: scaled scaled fitted fitted */
  69   ROLL,
  70   NEQ,
  71   IF, /* s: scaled fitted */
  72     PUSHB_1,
  73       2,
  74     CINDEX,
  75     SUB, /* s: scaled (fitted-scaled) */
  76     PUSHB_1,
  77       cvtl_0x10000,
  78     RCVT,
  79     MUL, /* (fitted-scaled) in 16.16 format */
  80     SWAP,
  81     DIV, /* ((fitted-scaled) / scaled) in 16.16 format */
  82
  83     PUSHB_1,
  84       cvtl_scale,
  85     SWAP,
  86     WCVTP,
  87
  88 };
  89
  90 unsigned char PREP(loop_cvt_a) [] = {
  91
  92     /* loop over vertical CVT entries */
  93     PUSHB_4,
  94
  95 };
  96
  97 /*    %c, first vertical index */
  98 /*    %c, last vertical index */
  99
 100 unsigned char PREP(loop_cvt_b) [] = {
 101
 102       bci_cvt_rescale,
 103       bci_loop,
 104     CALL,
 105
 106     /* loop over blue refs */
 107     PUSHB_4,
 108
 109 };
 110
 111 /*    %c, first blue ref index */
 112 /*    %c, last blue ref index */
 113
 114 unsigned char PREP(loop_cvt_c) [] = {
 115
 116       bci_cvt_rescale,
 117       bci_loop,
 118     CALL,
 119
 120     /* loop over blue shoots */
 121     PUSHB_4,
 122
 123 };
 124
 125 /*    %c, first blue shoot index */
 126 /*    %c, last blue shoot index */
 127
 128 unsigned char PREP(loop_cvt_d) [] = {
 129
 130       bci_cvt_rescale,
 131       bci_loop,
 132     CALL,
 133   EIF,
 134
 135 };
 136
 137 unsigned char PREP(compute_extra_light_a) [] = {
 138
 139   /* compute (vertical) `extra_light' flag */
 140   PUSHB_3,
 141     cvtl_is_extra_light,
 142     40,
 143
 144 };
 145
 146 /*  %c, index of vertical standard_width */
 147
 148 unsigned char PREP(compute_extra_light_b) [] = {
 149
 150   RCVT,
 151   GT, /* standard_width < 40 */
 152   WCVTP,
 153
 154 };
 155
 156 unsigned char PREP(round_blues_a) [] = {
 157
 158   /* use discrete values for blue zone widths */
 159   PUSHB_4,
 160
 161 };
 162
 163 /*  %c, first blue ref index */
 164 /*  %c, last blue ref index */
 165
 166 unsigned char PREP(round_blues_b) [] = {
 167
 168     bci_blue_round,
 169     bci_loop,
 170   CALL
 171
 172 };
 173
 174
 175 #define COPY_PREP(snippet_name) \
 176           memcpy(buf_p, prep_ ## snippet_name, \
 177                  sizeof (prep_ ## snippet_name)); \
 178           buf_p += sizeof (prep_ ## snippet_name);
 179
 180 static FT_Error
 181 TA_table_build_prep(FT_Byte** prep,
 182                     FT_ULong* prep_len,
 183                     FONT* font)
 184 {
 185   TA_LatinAxis vaxis;
 186   TA_LatinBlue blue_adjustment;
 187   FT_UInt i;
 188
 189   FT_UInt buf_len;
 190   FT_UInt len;
 191   FT_Byte* buf;
 192   FT_Byte* buf_p;
 193
 194
 195   vaxis = &((TA_LatinMetrics)font->loader->hints.metrics)->axis[1];
 196   blue_adjustment = NULL;
 197
 198   for (i = 0; i < vaxis->blue_count; i++)
 199   {
 200     if (vaxis->blues[i].flags & TA_LATIN_BLUE_ADJUSTMENT)
 201     {
 202       blue_adjustment = &vaxis->blues[i];
 203       break;
 204     }
 205   }
 206
 207   buf_len = sizeof (PREP(store_0x10000));
 208
 209   if (blue_adjustment)
 210     buf_len += sizeof (PREP(align_top_a))
 211                + 1
 212                + sizeof (PREP(align_top_b))
 213                + sizeof (PREP(loop_cvt_a))
 214                + 2
 215                + sizeof (PREP(loop_cvt_b))
 216                + 2
 217                + sizeof (PREP(loop_cvt_c))
 218                + 2
 219                + sizeof (PREP(loop_cvt_d));
 220
 221   buf_len += sizeof (PREP(compute_extra_light_a))
 222              + 1
 223              + sizeof (PREP(compute_extra_light_b));
 224
 225   if (CVT_BLUES_SIZE(font))
 226     buf_len += sizeof (PREP(round_blues_a))
 227                + 2
 228                + sizeof (PREP(round_blues_b));
 229
 230   /* buffer length must be a multiple of four */
 231   len = (buf_len + 3) & ~3;
 232   buf = (FT_Byte*)malloc(len);
 233   if (!buf)
 234     return FT_Err_Out_Of_Memory;
 235
 236   /* pad end of buffer with zeros */
 237   buf[len - 1] = 0x00;
 238   buf[len - 2] = 0x00;
 239   buf[len - 3] = 0x00;
 240
 241   /* copy cvt program into buffer and fill in the missing variables */
 242   buf_p = buf;
 243
 244   COPY_PREP(store_0x10000);
 245
 246   if (blue_adjustment)
 247   {
 248     COPY_PREP(align_top_a);
 249     *(buf_p++) = (unsigned char)(CVT_BLUE_SHOOTS_OFFSET(font)
 250                                  + blue_adjustment - vaxis->blues);
 251     COPY_PREP(align_top_b);
 252
 253     COPY_PREP(loop_cvt_a);
 254     *(buf_p++) = (unsigned char)CVT_VERT_WIDTHS_OFFSET(font);
 255     *(buf_p++) = (unsigned char)(CVT_VERT_WIDTHS_OFFSET(font)
 256                                  + CVT_VERT_WIDTHS_SIZE(font) - 1);
 257     COPY_PREP(loop_cvt_b);
 258     *(buf_p++) = (unsigned char)CVT_BLUE_REFS_OFFSET(font);
 259     *(buf_p++) = (unsigned char)(CVT_BLUE_REFS_OFFSET(font)
 260                                  + CVT_BLUES_SIZE(font) - 1);
 261     COPY_PREP(loop_cvt_c);
 262     *(buf_p++) = (unsigned char)CVT_BLUE_SHOOTS_OFFSET(font);
 263     *(buf_p++) = (unsigned char)(CVT_BLUE_SHOOTS_OFFSET(font)
 264                                  + CVT_BLUES_SIZE(font) - 1);
 265     COPY_PREP(loop_cvt_d);
 266   }
 267
 268   COPY_PREP(compute_extra_light_a);
 269   *(buf_p++) = (unsigned char)CVT_VERT_STANDARD_WIDTH_OFFSET(font);
 270   COPY_PREP(compute_extra_light_b);
 271
 272   if (CVT_BLUES_SIZE(font))
 273   {
 274     COPY_PREP(round_blues_a);
 275     *(buf_p++) = (unsigned char)CVT_BLUE_REFS_OFFSET(font);
 276     *(buf_p++) = (unsigned char)(CVT_BLUE_REFS_OFFSET(font)
 277                                  + CVT_BLUES_SIZE(font) - 1);
 278     COPY_PREP(round_blues_b);
 279   }
 280
 281   *prep = buf;
 282   *prep_len = buf_len;
 283
 284   return FT_Err_Ok;
 285 }
 286
 287
 288 FT_Error
 289 TA_sfnt_build_prep_table(SFNT* sfnt,
 290                          FONT* font)
 291 {
 292   FT_Error error;
 293
 294   FT_Byte* prep_buf;
 295   FT_ULong prep_len;
 296
 297
 298   error = TA_sfnt_add_table_info(sfnt);
 299   if (error)
 300     return error;
 301
 302   error = TA_table_build_prep(&prep_buf, &prep_len, font);
 303   if (error)
 304     return error;
 305
 306 #if 0
 307   /* ttfautohint's bytecode in `fpgm' is larger */
 308   /* than the bytecode in `prep'; */
 309   /* this commented out code here is just for completeness */
 310   if (prep_len > sfnt->max_instructions)
 311     sfnt->max_instructions = prep_len;
 312 #endif
 313
 314   /* in case of success, `prep_buf' gets linked */
 315   /* and is eventually freed in `TA_font_unload' */
 316   error = TA_font_add_table(font,
 317                             &sfnt->table_infos[sfnt->num_table_infos - 1],
 318                             TTAG_prep, prep_len, prep_buf);
 319   if (error)
 320   {
 321     free(prep_buf);
 322     return error;
 323   }
 324
 325   return FT_Err_Ok;
 326 }
 327
 328 /* end of taprep.c */