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/***************************************************************************/ /* */ /* ttinterp.c */ /* */ /* TrueType bytecode interpreter (body). */ /* */ /* Copyright 1996-2013 */ /* 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. */ /* */ /***************************************************************************/ /* Greg Hitchcock from Microsoft has helped a lot in resolving unclear */ /* issues; many thanks! */ #include <ft2build.h> #include FT_INTERNAL_DEBUG_H #include FT_INTERNAL_CALC_H #include FT_TRIGONOMETRY_H #include FT_SYSTEM_H #include "ttinterp.h" #include "tterrors.h" #include "ttsubpix.h" #ifdef TT_USE_BYTECODE_INTERPRETER /*************************************************************************/ /* */ /* The macro FT_COMPONENT is used in trace mode. It is an implicit */ /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */ /* messages during execution. */ /* */ #undef FT_COMPONENT #define FT_COMPONENT trace_ttinterp /*************************************************************************/ /* */ /* In order to detect infinite loops in the code, we set up a counter */ /* within the run loop. A single stroke of interpretation is now */ /* limited to a maximum number of opcodes defined below. */ /* */ #define MAX_RUNNABLE_OPCODES 1000000L /*************************************************************************/ /* */ /* There are two kinds of implementations: */ /* */ /* 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 fully re-entrant. */ /* */ /* The idea is that an indirect implementation may be slower to execute */ /* on low-end processors that are used in some systems (like 386s or */ /* even 486s). */ /* */ /* 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 code used for */ /* development. */ /* */ /* - It's much more readable that way! */ /* */ /* - It's still open to experimentation and tuning. */ /* */ /*************************************************************************/ #ifndef TT_CONFIG_OPTION_STATIC_INTERPRETER /* indirect implementation */ #define CUR (*exc) /* see ttobjs.h */ /*************************************************************************/ /* */ /* This macro is used whenever `exec' is unused in a function, to avoid */ /* stupid warnings from pedantic compilers. */ /* */ #define FT_UNUSED_EXEC FT_UNUSED( exc ) #else /* static implementation */ #define CUR cur #define FT_UNUSED_EXEC int __dummy = __dummy static TT_ExecContextRec 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 */ /*************************************************************************/ /* */ /* The instruction argument stack. */ /* */ #define INS_ARG EXEC_OP_ FT_Long* args /* see ttobjs.h for EXEC_OP_ */ /*************************************************************************/ /* */ /* This macro is used whenever `args' is unused in a function, to avoid */ /* stupid warnings from pedantic compilers. */ /* */ #define FT_UNUSED_ARG FT_UNUSED_EXEC; FT_UNUSED( args ) /*************************************************************************/ /* */ /* The following macros hide the use of EXEC_ARG and EXEC_ARG_ to */ /* increase readability of the code. */ /* */ /*************************************************************************/ #define SKIP_Code() \ SkipCode( EXEC_ARG ) #define GET_ShortIns() \ GetShortIns( EXEC_ARG ) #define NORMalize( x, y, v ) \ Normalize( EXEC_ARG_ x, y, v ) #define SET_SuperRound( scale, flags ) \