ttinterp.c

神龙卡开发原代码

/*******************************************************************
 *
 *  ttinterp.c                                              3.1
 *
 *  TrueType bytecode intepreter.
 *
 *  Copyright 1996-1999 by
 *  David Turner, Robert Wilhelm, and Werner Lemberg
 *
 *  This file is part of the FreeType project, and may only be used
 *  modified and distributed under the terms of the FreeType project
 *  license, LICENSE.TXT.  By continuing to use, modify, or distribute
 *  this file you indicate that you have read the license and
 *  understand and accept it fully.
 *
 *
 *  Changes between 3.1 and 3.0:
 *
 *  - A more relaxed version of the interpreter.  It is now able to
 *    ignore errors like out-of-bound array access and writes in order
 *    to silently support broken glyphs (even if the results are not
 *    always pretty).
 *
 *    Note that one can use the flag TTLOAD_PEDANTIC to force
 *    TrueType-compliant interpretation.
 *
 *  - A big #if used to completely disable the interpreter, which
 *    is due to the Apple patents issues which emerged recently.
 *
 ******************************************************************/

#include "freetype.h"
#include "tttypes.h"
#include "ttdebug.h"
#include "ttcalc.h"
#include "ttmemory.h"
#include "ttinterp.h"


#ifdef TT_CONFIG_OPTION_NO_INTERPRETER

  LOCAL_FUNC
  TT_Error  RunIns( PExecution_Context  exc )
  {
    /* do nothing - always successful */
    (void)exc;
    return TT_Err_Ok;
  }

#else


#ifdef DEBUG_INTERPRETER
#include <memory.h>
#include "ttdebug.h"

/* Define the `getch()' function.  On Unix systems, it is an alias  */
/* for `getchar()', and the debugger front end must ensure that the */
/* `stdin' file descriptor is not in line-by-line input mode.       */
#ifdef OS2
#include <conio.h>
#else
#define getch  getchar
#endif

#endif /* DEBUG_INTEPRETER */


/* required by the tracing mode */
#undef  TT_COMPONENT
#define TT_COMPONENT      trace_interp


/* In order to detect infinite loops in the code, we set-up         */
/* a counter within the run loop. a singly stroke of interpretation */
/* is now limited to a maximum number of opcodes defined below..    */
/*                                                                  */
#define MAX_RUNNABLE_OPCODES  1000000


/* There are two kinds of implementations there:              */
/*                                                            */
/* a. static implementation:                                  */
/*                                                            */
/*    The current execution context is a static variable,     */
/*    which fields are accessed directly by the interpreter   */
/*    during execution.  The context is named 'cur'.          */
/*                                                            */
/*    This version is non-reentrant, of course.               */
/*                                                            */
/*                                                            */
/* b. indirect implementation:                                */
/*                                                            */
/*    The current execution context is passed to _each_       */
/*    function as its first argument, and each field is       */
/*    thus accessed indirectly.                               */
/*                                                            */
/*    This version is, however, fully re-entrant.             */
/*                                                            */
/*                                                            */
/*  The idea is that an indirect implementation may be        */
/*  slower to execute on the low-end processors that are      */
/*  used in some systems (like 386s or even 486s).            */
/*                                                            */
/*  When the interpreter started, we had no idea of the       */
/*  time that glyph hinting (i.e. executing instructions)     */
/*  could take in the whole process of rendering a glyph,     */
/*  and a 10 to 30% performance penalty on low-end systems    */
/*  didn't seem much of a good idea.  This question led us    */
/*  to provide two distinct builds of the C version from      */
/*  a single source, with the use of macros (again).          */
/*                                                            */
/*  Now that the engine is working (and working really        */
/*  well!), it seems that the greatest time-consuming         */
/*  factors are: file i/o, glyph loading, rasterizing and     */
/*  _then_ glyph hinting!                                     */
/*                                                            */
/*  Tests performed with two versions of the 'fttimer'        */
/*  program seem to indicate that hinting takes less than 5%  */
/*  of the rendering process, which is dominated by glyph     */
/*  loading and scan-line conversion by an high order of      */
/*  magnitude.                                                */
/*                                                            */
/*  As a consequence, the indirect implementation is now the  */
/*  default, as its performance costs can be considered       */
/*  negligible in our context. Note, however, that we         */
/*  kept the same source with macros because:                 */
/*                                                            */
/*    - the code is kept very close in design to the          */
/*      Pascal one used for development.                      */
/*                                                            */
/*    - it's much more readable that way!                     */
/*                                                            */
/*    - it's still open to later experimentation and tuning   */



#ifndef TT_CONFIG_OPTION_STATIC_INTERPRETER      /* indirect implementation */

#define CUR (*exc)                 /* see ttobjs.h */

#else                              /* static implementation */

#define CUR cur

  static TExecution_Context  cur;  /* static exec. context variable */

  /* apparently, we have a _lot_ of direct indexing when accessing  */
  /* the static 'cur', which makes the code bigger (due to all the  */
  /* four bytes addresses).                                         */

#endif  /* !TT_CONFIG_OPTION_STATIC_INTERPRETER */


#define INS_ARG         EXEC_OPS PStorage args  /* see ttobjs.h */

#define SKIP_Code()     SkipCode( EXEC_ARG )

#define GET_ShortIns()  GetShortIns( EXEC_ARG )

#define COMPUTE_Funcs() Compute_Funcs( EXEC_ARG )

#define NORMalize( x, y, v )  Normalize( EXEC_ARGS x, y, v )

#define SET_SuperRound( scale, flags ) \
                        SetSuperRound( EXEC_ARGS scale, flags )

#define INS_Goto_CodeRange( range, ip ) \
                        Ins_Goto_CodeRange( EXEC_ARGS range, ip )

#define CUR_Func_project( x, y )   CUR.func_project( EXEC_ARGS x, y )
#define CUR_Func_move( z, p, d )   CUR.func_move( EXEC_ARGS z, p, d )
#define CUR_Func_dualproj( x, y )  CUR.func_dualproj( EXEC_ARGS x, y )
#define CUR_Func_freeProj( x, y )  CUR.func_freeProj( EXEC_ARGS x, y )
#define CUR_Func_round( d, c )     CUR.func_round( EXEC_ARGS d, c )

#define CUR_Func_read_cvt( index )       \
          CUR.func_read_cvt( EXEC_ARGS index )

#define CUR_Func_write_cvt( index, val ) \
          CUR.func_write_cvt( EXEC_ARGS index, val )

#define CUR_Func_move_cvt( index, val )  \
          CUR.func_move_cvt( EXEC_ARGS index, val )

#define CURRENT_Ratio()  Current_Ratio( EXEC_ARG )
#define CURRENT_Ppem()   Current_Ppem( EXEC_ARG )

#define CALC_Length()  Calc_Length( EXEC_ARG )

#define INS_SxVTL( a, b, c, d ) Ins_SxVTL( EXEC_ARGS a, b, c, d )

#define COMPUTE_Point_Displacement( a, b, c, d ) \
           Compute_Point_Displacement( EXEC_ARGS a, b, c, d )

#define MOVE_Zp2_Point( a, b, c, t )  Move_Zp2_Point( EXEC_ARGS a, b, c, t )

#define CUR_Ppem()  Cur_PPEM( EXEC_ARG )

  /* Instruction dispatch function, as used by the interpreter */
  typedef void  (*TInstruction_Function)( INS_ARG );

#define BOUNDS( x, n )  ( (x) >= (n) )



/*********************************************************************/
/*                                                                   */
/*  Before an opcode is executed, the interpreter verifies that      */
/*  there are enough arguments on the stack, with the help of        */
/*  the Pop_Push_Count table.                                        */
/*                                                                   */
/*  For each opcode, the first column gives the number of arguments  */
/*  that are popped from the stack; the second one gives the number  */
/*  of those that are pushed in result.                              */
/*                                                                   */
/*  Note that for opcodes with a varying number of parameters,       */
/*  either 0 or 1 arg is verified before execution, depending        */
/*  on the nature of the instruction:                                */
/*                                                                   */
/*   - if the number of arguments is given by the bytecode           */
/*     stream or the loop variable, 0 is chosen.                     */
/*                                                                   */
/*   - if the first argument is a count n that is followed           */
/*     by arguments a1..an, then 1 is chosen.                        */
/*                                                                   */
/*********************************************************************/

#undef  PACK
#define PACK( x, y )  ((x << 4) | y)

  static const Byte  Pop_Push_Count[256] =
  {
    /* opcodes are gathered in groups of 16 */
    /* please keep the spaces as they are   */

    /*  SVTCA  y  */  PACK( 0, 0 ),
    /*  SVTCA  x  */  PACK( 0, 0 ),
    /*  SPvTCA y  */  PACK( 0, 0 ),
    /*  SPvTCA x  */  PACK( 0, 0 ),
    /*  SFvTCA y  */  PACK( 0, 0 ),
    /*  SFvTCA x  */  PACK( 0, 0 ),
    /*  SPvTL //  */  PACK( 2, 0 ),
    /*  SPvTL +   */  PACK( 2, 0 ),
    /*  SFvTL //  */  PACK( 2, 0 ),
    /*  SFvTL +   */  PACK( 2, 0 ),
    /*  SPvFS     */  PACK( 2, 0 ),
    /*  SFvFS     */  PACK( 2, 0 ),
    /*  GPV       */  PACK( 0, 2 ),
    /*  GFV       */  PACK( 0, 2 ),
    /*  SFvTPv    */  PACK( 0, 0 ),
    /*  ISECT     */  PACK( 5, 0 ),

    /*  SRP0      */  PACK( 1, 0 ),
    /*  SRP1      */  PACK( 1, 0 ),
    /*  SRP2      */  PACK( 1, 0 ),
    /*  SZP0      */  PACK( 1, 0 ),
    /*  SZP1      */  PACK( 1, 0 ),
    /*  SZP2      */  PACK( 1, 0 ),
    /*  SZPS      */  PACK( 1, 0 ),
    /*  SLOOP     */  PACK( 1, 0 ),
    /*  RTG       */  PACK( 0, 0 ),
    /*  RTHG      */  PACK( 0, 0 ),
    /*  SMD       */  PACK( 1, 0 ),
    /*  ELSE      */  PACK( 0, 0 ),
    /*  JMPR      */  PACK( 1, 0 ),
    /*  SCvTCi    */  PACK( 1, 0 ),
    /*  SSwCi     */  PACK( 1, 0 ),
    /*  SSW       */  PACK( 1, 0 ),

    /*  DUP       */  PACK( 1, 2 ),
    /*  POP       */  PACK( 1, 0 ),
    /*  CLEAR     */  PACK( 0, 0 ),
    /*  SWAP      */  PACK( 2, 2 ),
    /*  DEPTH     */  PACK( 0, 1 ),
    /*  CINDEX    */  PACK( 1, 1 ),
    /*  MINDEX    */  PACK( 1, 0 ),
    /*  AlignPTS  */  PACK( 2, 0 ),
    /*  INS_$28   */  PACK( 0, 0 ),
    /*  UTP       */  PACK( 1, 0 ),
    /*  LOOPCALL  */  PACK( 2, 0 ),
    /*  CALL      */  PACK( 1, 0 ),
    /*  FDEF      */  PACK( 1, 0 ),
    /*  ENDF      */  PACK( 0, 0 ),
    /*  MDAP[0]   */  PACK( 1, 0 ),
    /*  MDAP[1]   */  PACK( 1, 0 ),

    /*  IUP[0]    */  PACK( 0, 0 ),
    /*  IUP[1]    */  PACK( 0, 0 ),
    /*  SHP[0]    */  PACK( 0, 0 ),
    /*  SHP[1]    */  PACK( 0, 0 ),
    /*  SHC[0]    */  PACK( 1, 0 ),
    /*  SHC[1]    */  PACK( 1, 0 ),
    /*  SHZ[0]    */  PACK( 1, 0 ),
    /*  SHZ[1]    */  PACK( 1, 0 ),
    /*  SHPIX     */  PACK( 1, 0 ),
    /*  IP        */  PACK( 0, 0 ),
    /*  MSIRP[0]  */  PACK( 2, 0 ),
    /*  MSIRP[1]  */  PACK( 2, 0 ),
    /*  AlignRP   */  PACK( 0, 0 ),
    /*  RTDG      */  PACK( 0, 0 ),
    /*  MIAP[0]   */  PACK( 2, 0 ),
    /*  MIAP[1]   */  PACK( 2, 0 ),

    /*  NPushB    */  PACK( 0, 0 ),
    /*  NPushW    */  PACK( 0, 0 ),
    /*  WS        */  PACK( 2, 0 ),
    /*  RS        */  PACK( 1, 1 ),
    /*  WCvtP     */  PACK( 2, 0 ),
    /*  RCvt      */  PACK( 1, 1 ),
    /*  GC[0]     */  PACK( 1, 1 ),
    /*  GC[1]     */  PACK( 1, 1 ),
    /*  SCFS      */  PACK( 2, 0 ),
    /*  MD[0]     */  PACK( 2, 1 ),
    /*  MD[1]     */  PACK( 2, 1 ),
    /*  MPPEM     */  PACK( 0, 1 ),
    /*  MPS       */  PACK( 0, 1 ),
    /*  FlipON    */  PACK( 0, 0 ),
    /*  FlipOFF   */  PACK( 0, 0 ),
    /*  DEBUG     */  PACK( 1, 0 ),

    /*  LT        */  PACK( 2, 1 ),
    /*  LTEQ      */  PACK( 2, 1 ),
    /*  GT        */  PACK( 2, 1 ),
    /*  GTEQ      */  PACK( 2, 1 ),
    /*  EQ        */  PACK( 2, 1 ),
    /*  NEQ       */  PACK( 2, 1 ),
    /*  ODD       */  PACK( 1, 1 ),
    /*  EVEN      */  PACK( 1, 1 ),
    /*  IF        */  PACK( 1, 0 ),
    /*  EIF       */  PACK( 0, 0 ),
    /*  AND       */  PACK( 2, 1 ),
    /*  OR        */  PACK( 2, 1 ),
    /*  NOT       */  PACK( 1, 1 ),
    /*  DeltaP1   */  PACK( 1, 0 ),
    /*  SDB       */  PACK( 1, 0 ),
    /*  SDS       */  PACK( 1, 0 ),

    /*  ADD       */  PACK( 2, 1 ),
    /*  SUB       */  PACK( 2, 1 ),
    /*  DIV       */  PACK( 2, 1 ),
    /*  MUL       */  PACK( 2, 1 ),
    /*  ABS       */  PACK( 1, 1 ),
    /*  NEG       */  PACK( 1, 1 ),
    /*  FLOOR     */  PACK( 1, 1 ),
    /*  CEILING   */  PACK( 1, 1 ),
    /*  ROUND[0]  */  PACK( 1, 1 ),
    /*  ROUND[1]  */  PACK( 1, 1 ),
    /*  ROUND[2]  */  PACK( 1, 1 ),
    /*  ROUND[3]  */  PACK( 1, 1 ),
    /*  NROUND[0] */  PACK( 1, 1 ),
    /*  NROUND[1] */  PACK( 1, 1 ),
    /*  NROUND[2] */  PACK( 1, 1 ),
    /*  NROUND[3] */  PACK( 1, 1 ),

    /*  WCvtF     */  PACK( 2, 0 ),
    /*  DeltaP2   */  PACK( 1, 0 ),
    /*  DeltaP3   */  PACK( 1, 0 ),
    /*  DeltaCn[0] */ PACK( 1, 0 ),
    /*  DeltaCn[1] */ PACK( 1, 0 ),
    /*  DeltaCn[2] */ PACK( 1, 0 ),
    /*  SROUND    */  PACK( 1, 0 ),
    /*  S45Round  */  PACK( 1, 0 ),
    /*  JROT      */  PACK( 2, 0 ),
    /*  JROF      */  PACK( 2, 0 ),
    /*  ROFF      */  PACK( 0, 0 ),
    /*  INS_$7B   */  PACK( 0, 0 ),
    /*  RUTG      */  PACK( 0, 0 ),
    /*  RDTG      */  PACK( 0, 0 ),
    /*  SANGW     */  PACK( 1, 0 ),
    /*  AA        */  PACK( 1, 0 ),

    /*  FlipPT    */  PACK( 0, 0 ),
    /*  FlipRgON  */  PACK( 2, 0 ),
    /*  FlipRgOFF */  PACK( 2, 0 ),
    /*  INS_$83   */  PACK( 0, 0 ),
    /*  INS_$84   */  PACK( 0, 0 ),
    /*  ScanCTRL  */  PACK( 1, 0 ),
    /*  SDVPTL[0] */  PACK( 2, 0 ),
    /*  SDVPTL[1] */  PACK( 2, 0 ),
    /*  GetINFO   */  PACK( 1, 1 ),
    /*  IDEF      */  PACK( 1, 0 ),
    /*  ROLL      */  PACK( 3, 3 ),
    /*  MAX       */  PACK( 2, 1 ),
    /*  MIN       */  PACK( 2, 1 ),
    /*  ScanTYPE  */  PACK( 1, 0 ),
    /*  InstCTRL  */  PACK( 2, 0 ),
    /*  INS_$8F   */  PACK( 0, 0 ),

    /*  INS_$90  */   PACK( 0, 0 ),
    /*  INS_$91  */   PACK( 0, 0 ),
    /*  INS_$92  */   PACK( 0, 0 ),
    /*  INS_$93  */   PACK( 0, 0 ),
    /*  INS_$94  */   PACK( 0, 0 ),
    /*  INS_$95  */   PACK( 0, 0 ),
    /*  INS_$96  */   PACK( 0, 0 ),
    /*  INS_$97  */   PACK( 0, 0 ),
    /*  INS_$98  */   PACK( 0, 0 ),
    /*  INS_$99  */   PACK( 0, 0 ),
    /*  INS_$9A  */   PACK( 0, 0 ),
    /*  INS_$9B  */   PACK( 0, 0 ),
    /*  INS_$9C  */   PACK( 0, 0 ),
    /*  INS_$9D  */   PACK( 0, 0 ),
    /*  INS_$9E  */   PACK( 0, 0 ),
    /*  INS_$9F  */   PACK( 0, 0 ),

    /*  INS_$A0  */   PACK( 0, 0 ),
    /*  INS_$A1  */   PACK( 0, 0 ),
    /*  INS_$A2  */   PACK( 0, 0 ),
    /*  INS_$A3  */   PACK( 0, 0 ),
    /*  INS_$A4  */   PACK( 0, 0 ),
    /*  INS_$A5  */   PACK( 0, 0 ),
    /*  INS_$A6  */   PACK( 0, 0 ),
    /*  INS_$A7  */   PACK( 0, 0 ),
    /*  INS_$A8  */   PACK( 0, 0 ),
    /*  INS_$A9  */   PACK( 0, 0 ),
    /*  INS_$AA  */   PACK( 0, 0 ),
    /*  INS_$AB  */   PACK( 0, 0 ),
    /*  INS_$AC  */   PACK( 0, 0 ),
    /*  INS_$AD  */   PACK( 0, 0 ),
    /*  INS_$AE  */   PACK( 0, 0 ),
    /*  INS_$AF  */   PACK( 0, 0 ),

    /*  PushB[0]  */  PACK( 0, 1 ),
    /*  PushB[1]  */  PACK( 0, 2 ),
    /*  PushB[2]  */  PACK( 0, 3 ),
    /*  PushB[3]  */  PACK( 0, 4 ),
    /*  PushB[4]  */  PACK( 0, 5 ),
    /*  PushB[5]  */  PACK( 0, 6 ),
    /*  PushB[6]  */  PACK( 0, 7 ),
    /*  PushB[7]  */  PACK( 0, 8 ),
    /*  PushW[0]  */  PACK( 0, 1 ),
    /*  PushW[1]  */  PACK( 0, 2 ),
    /*  PushW[2]  */  PACK( 0, 3 ),
    /*  PushW[3]  */  PACK( 0, 4 ),
    /*  PushW[4]  */  PACK( 0, 5 ),
    /*  PushW[5]  */  PACK( 0, 6 ),
    /*  PushW[6]  */  PACK( 0, 7 ),
    /*  PushW[7]  */  PACK( 0, 8 ),

    /*  MDRP[00]  */  PACK( 1, 0 ),
    /*  MDRP[01]  */  PACK( 1, 0 ),
    /*  MDRP[02]  */  PACK( 1, 0 ),
    /*  MDRP[03]  */  PACK( 1, 0 ),
    /*  MDRP[04]  */  PACK( 1, 0 ),
    /*  MDRP[05]  */  PACK( 1, 0 ),
    /*  MDRP[06]  */  PACK( 1, 0 ),
    /*  MDRP[07]  */  PACK( 1, 0 ),
    /*  MDRP[08]  */  PACK( 1, 0 ),
    /*  MDRP[09]  */  PACK( 1, 0 ),
    /*  MDRP[10]  */  PACK( 1, 0 ),
    /*  MDRP[11]  */  PACK( 1, 0 ),
    /*  MDRP[12]  */  PACK( 1, 0 ),
    /*  MDRP[13]  */  PACK( 1, 0 ),
    /*  MDRP[14]  */  PACK( 1, 0 ),
    /*  MDRP[15]  */  PACK( 1, 0 ),

    /*  MDRP[16]  */  PACK( 1, 0 ),
    /*  MDRP[17]  */  PACK( 1, 0 ),
    /*  MDRP[18]  */  PACK( 1, 0 ),
    /*  MDRP[19]  */  PACK( 1, 0 ),
    /*  MDRP[20]  */  PACK( 1, 0 ),
    /*  MDRP[21]  */  PACK( 1, 0 ),
    /*  MDRP[22]  */  PACK( 1, 0 ),