Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 782 insertions, 0 deletions

diff --git a/gfx/graphite2/src/Code.cpp b/gfx/graphite2/src/Code.cpp
new file mode 100644
index 0000000000..ec5ab298ca
--- /dev/null
+++ b/gfx/graphite2/src/Code.cpp
@@ -0,0 +1,782 @@
+/*  GRAPHITE2 LICENSING
+
+    Copyright 2010, SIL International
+    All rights reserved.
+
+    This library is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should also have received a copy of the GNU Lesser General Public
+    License along with this library in the file named "LICENSE".
+    If not, write to the Free Software Foundation, 51 Franklin Street,
+    Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
+    internet at http://www.fsf.org/licenses/lgpl.html.
+
+Alternatively, the contents of this file may be used under the terms of the
+Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
+License, as published by the Free Software Foundation, either version 2
+of the License or (at your option) any later version.
+*/
+// This class represents loaded graphite stack machine code.  It performs
+// basic sanity checks, on the incoming code to prevent more obvious problems
+// from crashing graphite.
+// Author: Tim Eves
+
+#include <cassert>
+#include <cstddef>
+#include <cstdlib>
+#include <cstring>
+#include "graphite2/Segment.h"
+#include "inc/Code.h"
+#include "inc/Face.h"
+#include "inc/GlyphFace.h"
+#include "inc/GlyphCache.h"
+#include "inc/Machine.h"
+#include "inc/Rule.h"
+#include "inc/Silf.h"
+
+#include <cstdio>
+
+#ifdef NDEBUG
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#endif
+#endif
+
+
+using namespace graphite2;
+using namespace vm;
+
+namespace {
+
+inline bool is_return(const instr i) {
+    const opcode_t * opmap = Machine::getOpcodeTable();
+    const instr pop_ret  = *opmap[POP_RET].impl,
+                ret_zero = *opmap[RET_ZERO].impl,
+                ret_true = *opmap[RET_TRUE].impl;
+    return i == pop_ret || i == ret_zero || i == ret_true;
+}
+
+struct context
+{
+    context(uint8 ref=0) : codeRef(ref) {flags.changed=false; flags.referenced=false;}
+    struct {
+        uint8   changed:1,
+                referenced:1;
+    } flags;
+    uint8       codeRef;
+};
+
+} // end namespace
+
+
+class Machine::Code::decoder
+{
+public:
+    struct limits;
+    static const int NUMCONTEXTS = 256;
+
+    decoder(limits & lims, Code &code, enum passtype pt) throw();
+
+    bool        load(const byte * bc_begin, const byte * bc_end);
+    void        apply_analysis(instr * const code, instr * code_end);
+    byte        max_ref() { return _max_ref; }
+    int         out_index() const { return _out_index; }
+
+private:
+    void        set_ref(int index) throw();
+    void        set_noref(int index) throw();
+    void        set_changed(int index) throw();
+    opcode      fetch_opcode(const byte * bc);
+    void        analyse_opcode(const opcode, const int8 * const dp) throw();
+    bool        emit_opcode(opcode opc, const byte * & bc);
+    bool        validate_opcode(const byte opc, const byte * const bc);
+    bool        valid_upto(const uint16 limit, const uint16 x) const throw();
+    bool        test_context() const throw();
+    bool        test_ref(int8 index) const throw();
+    bool        test_attr(attrCode attr) const throw();
+    void        failure(const status_t s) const throw() { _code.failure(s); }
+
+    Code              & _code;
+    int                 _out_index;
+    uint16              _out_length;
+    instr             * _instr;
+    byte              * _data;
+    limits            & _max;
+    enum passtype       _passtype;
+    int                 _stack_depth;
+    bool                _in_ctxt_item;
+    int16               _slotref;
+    context             _contexts[NUMCONTEXTS];
+    byte                _max_ref;
+};
+
+
+struct Machine::Code::decoder::limits
+{
+  const byte       * bytecode;
+  const uint8        pre_context;
+  const uint16       rule_length,
+                     classes,
+                     glyf_attrs,
+                     features;
+  const byte         attrid[gr_slatMax];
+};
+
+inline Machine::Code::decoder::decoder(limits & lims, Code &code, enum passtype pt) throw()
+: _code(code),
+  _out_index(code._constraint ? 0 : lims.pre_context),
+  _out_length(code._constraint ? 1 : lims.rule_length),
+  _instr(code._code), _data(code._data), _max(lims), _passtype(pt),
+  _stack_depth(0),
+  _in_ctxt_item(false),
+  _slotref(0),
+  _max_ref(0)
+{ }
+
+
+
+Machine::Code::Code(bool is_constraint, const byte * bytecode_begin, const byte * const bytecode_end,
+           uint8 pre_context, uint16 rule_length, const Silf & silf, const Face & face,
+           enum passtype pt, byte * * const _out)
+ :  _code(0), _data(0), _data_size(0), _instr_count(0), _max_ref(0), _status(loaded),
+    _constraint(is_constraint), _modify(false), _delete(false), _own(_out==0)
+{
+#ifdef GRAPHITE2_TELEMETRY
+    telemetry::category _code_cat(face.tele.code);
+#endif
+    assert(bytecode_begin != 0);
+    if (bytecode_begin == bytecode_end)
+    {
+      // ::new (this) Code();
+      return;
+    }
+    assert(bytecode_end > bytecode_begin);
+    const opcode_t *    op_to_fn = Machine::getOpcodeTable();
+
+    // Allocate code and data target buffers, these sizes are a worst case
+    // estimate.  Once we know their real sizes the we'll shrink them.
+    if (_out)   _code = reinterpret_cast<instr *>(*_out);
+    else        _code = static_cast<instr *>(malloc(estimateCodeDataOut(bytecode_end-bytecode_begin, 1, is_constraint ? 0 : rule_length)));
+    _data = reinterpret_cast<byte *>(_code + (bytecode_end - bytecode_begin));
+
+    if (!_code || !_data) {
+        failure(alloc_failed);
+        return;
+    }
+
+    decoder::limits lims = {
+        bytecode_end,
+        pre_context,
+        rule_length,
+        silf.numClasses(),
+        face.glyphs().numAttrs(),
+        face.numFeatures(),
+        {1,1,1,1,1,1,1,1,
+         1,1,1,1,1,1,1,255,
+         1,1,1,1,1,1,1,1,
+         1,1,1,1,1,1,0,0,
+         0,0,0,0,0,0,0,0,
+         0,0,0,0,0,0,0,0,
+         0,0,0,0,0,0,0, silf.numUser()}
+    };
+
+    decoder dec(lims, *this, pt);
+    if(!dec.load(bytecode_begin, bytecode_end))
+       return;
+
+    // Is this an empty program?
+    if (_instr_count == 0)
+    {
+      release_buffers();
+      ::new (this) Code();
+      return;
+    }
+
+    // When we reach the end check we've terminated it correctly
+    if (!is_return(_code[_instr_count-1])) {
+        failure(missing_return);
+        return;
+    }
+
+    assert((_constraint && immutable()) || !_constraint);
+    dec.apply_analysis(_code, _code + _instr_count);
+    _max_ref = dec.max_ref();
+
+    // Now we know exactly how much code and data the program really needs
+    // realloc the buffers to exactly the right size so we don't waste any
+    // memory.
+    assert((bytecode_end - bytecode_begin) >= ptrdiff_t(_instr_count));
+    assert((bytecode_end - bytecode_begin) >= ptrdiff_t(_data_size));
+    memmove(_code + (_instr_count+1), _data, _data_size*sizeof(byte));
+    size_t const total_sz = ((_instr_count+1) + (_data_size + sizeof(instr)-1)/sizeof(instr))*sizeof(instr);
+    if (_out)
+        *_out += total_sz;
+    else
+    {
+      instr * const old_code = _code;
+      _code = static_cast<instr *>(realloc(_code, total_sz));
+      if (!_code) free(old_code);
+    }
+   _data = reinterpret_cast<byte *>(_code + (_instr_count+1));
+
+    if (!_code)
+    {
+        failure(alloc_failed);
+        return;
+    }
+
+    // Make this RET_ZERO, we should never reach this but just in case ...
+    _code[_instr_count] = op_to_fn[RET_ZERO].impl[_constraint];
+
+#ifdef GRAPHITE2_TELEMETRY
+    telemetry::count_bytes(_data_size + (_instr_count+1)*sizeof(instr));
+#endif
+}
+
+Machine::Code::~Code() throw ()
+{
+    if (_own)
+        release_buffers();
+}
+
+
+bool Machine::Code::decoder::load(const byte * bc, const byte * bc_end)
+{
+    _max.bytecode = bc_end;
+    while (bc < bc_end)
+    {
+        const opcode opc = fetch_opcode(bc++);
+        if (opc == vm::MAX_OPCODE)
+            return false;
+
+        analyse_opcode(opc, reinterpret_cast<const int8 *>(bc));
+
+        if (!emit_opcode(opc, bc))
+            return false;
+    }
+
+    return bool(_code);
+}
+
+// Validation check and fixups.
+//
+
+opcode Machine::Code::decoder::fetch_opcode(const byte * bc)
+{
+    const byte opc = *bc++;
+
+    // Do some basic sanity checks based on what we know about the opcode
+    if (!validate_opcode(opc, bc))  return MAX_OPCODE;
+
+    // And check its arguments as far as possible
+    switch (opcode(opc))
+    {
+        case NOP :
+            break;
+        case PUSH_BYTE :
+        case PUSH_BYTEU :
+        case PUSH_SHORT :
+        case PUSH_SHORTU :
+        case PUSH_LONG :
+            ++_stack_depth;
+            break;
+        case ADD :
+        case SUB :
+        case MUL :
+        case DIV :
+        case MIN_ :
+        case MAX_ :
+        case AND :
+        case OR :
+        case EQUAL :
+        case NOT_EQ :
+        case LESS :
+        case GTR :
+        case LESS_EQ :
+        case GTR_EQ :
+        case BITOR :
+        case BITAND :
+            if (--_stack_depth <= 0)
+                failure(underfull_stack);
+            break;
+        case NEG :
+        case TRUNC8 :
+        case TRUNC16 :
+        case NOT :
+        case BITNOT :
+        case BITSET :
+            if (_stack_depth <= 0)
+                failure(underfull_stack);
+            break;
+        case COND :
+            _stack_depth -= 2;
+            if (_stack_depth <= 0)
+                failure(underfull_stack);
+            break;
+        case NEXT_N :           // runtime checked
+            break;
+        case NEXT :
+        case COPY_NEXT :
+            ++_out_index;
+            if (_out_index < -1 || _out_index > _out_length || _slotref > _max.rule_length)
+                failure(out_of_range_data);
+            break;
+        case PUT_GLYPH_8BIT_OBS :
+            valid_upto(_max.classes, bc[0]);
+            test_context();
+            break;
+        case PUT_SUBS_8BIT_OBS :
+            test_ref(int8(bc[0]));
+            valid_upto(_max.classes, bc[1]);
+            valid_upto(_max.classes, bc[2]);
+            test_context();
+            break;
+        case PUT_COPY :
+            test_ref(int8(bc[0]));
+            test_context();
+            break;
+        case INSERT :
+            if (_passtype >= PASS_TYPE_POSITIONING)
+                failure(invalid_opcode);
+            ++_out_length;
+            if (_out_index < 0) ++_out_index;
+            if (_out_index < -1 || _out_index >= _out_length)
+                failure(out_of_range_data);
+            break;
+        case DELETE :
+            if (_passtype >= PASS_TYPE_POSITIONING)
+                failure(invalid_opcode);
+            if (_out_index < _max.pre_context)
+                failure(out_of_range_data);
+            --_out_index;
+            --_out_length;
+            if (_out_index < -1 || _out_index > _out_length)
+                failure(out_of_range_data);
+            break;
+        case ASSOC :
+            if (bc[0] == 0)
+                failure(out_of_range_data);
+            for (uint8 num = bc[0]; num; --num)
+                test_ref(int8(bc[num]));
+            test_context();
+            break;
+        case CNTXT_ITEM :
+            valid_upto(_max.rule_length, _max.pre_context + int8(bc[0]));
+            if (bc + 2 + bc[1] >= _max.bytecode)    failure(jump_past_end);
+            if (_in_ctxt_item)                      failure(nested_context_item);
+            break;
+        case ATTR_SET :
+        case ATTR_ADD :
+        case ATTR_SUB :
+        case ATTR_SET_SLOT :
+            if (--_stack_depth < 0)
+                failure(underfull_stack);
+            valid_upto(gr_slatMax, bc[0]);
+            if (attrCode(bc[0]) == gr_slatUserDefn)     // use IATTR for user attributes
+                failure(out_of_range_data);
+            test_attr(attrCode(bc[0]));
+            test_context();
+            break;
+        case IATTR_SET_SLOT :
+            if (--_stack_depth < 0)
+                failure(underfull_stack);
+            if (valid_upto(gr_slatMax, bc[0]))
+                valid_upto(_max.attrid[bc[0]], bc[1]);
+            test_attr(attrCode(bc[0]));
+            test_context();
+            break;
+        case PUSH_SLOT_ATTR :
+            ++_stack_depth;
+            valid_upto(gr_slatMax, bc[0]);
+            test_ref(int8(bc[1]));
+            if (attrCode(bc[0]) == gr_slatUserDefn)     // use IATTR for user attributes
+                failure(out_of_range_data);
+            test_attr(attrCode(bc[0]));
+            break;
+        case PUSH_GLYPH_ATTR_OBS :
+        case PUSH_ATT_TO_GATTR_OBS :
+            ++_stack_depth;
+            valid_upto(_max.glyf_attrs, bc[0]);
+            test_ref(int8(bc[1]));
+            break;
+        case PUSH_ATT_TO_GLYPH_METRIC :
+        case PUSH_GLYPH_METRIC :
+            ++_stack_depth;
+            valid_upto(kgmetDescent, bc[0]);
+            test_ref(int8(bc[1]));
+            // level: dp[2] no check necessary
+            break;
+        case PUSH_FEAT :
+            ++_stack_depth;
+            valid_upto(_max.features, bc[0]);
+            test_ref(int8(bc[1]));
+            break;
+        case PUSH_ISLOT_ATTR :
+            ++_stack_depth;
+            if (valid_upto(gr_slatMax, bc[0]))
+            {
+                test_ref(int8(bc[1]));
+                valid_upto(_max.attrid[bc[0]], bc[2]);
+            }
+            test_attr(attrCode(bc[0]));
+            break;
+        case PUSH_IGLYPH_ATTR :// not implemented
+            ++_stack_depth;
+            break;
+        case POP_RET :
+            if (--_stack_depth < 0)
+                failure(underfull_stack);
+            GR_FALLTHROUGH;
+            // no break
+        case RET_ZERO :
+        case RET_TRUE :
+            break;
+        case IATTR_SET :
+        case IATTR_ADD :
+        case IATTR_SUB :
+            if (--_stack_depth < 0)
+                failure(underfull_stack);
+            if (valid_upto(gr_slatMax, bc[0]))
+                valid_upto(_max.attrid[bc[0]], bc[1]);
+            test_attr(attrCode(bc[0]));
+            test_context();
+            break;
+        case PUSH_PROC_STATE :  // dummy: dp[0] no check necessary
+        case PUSH_VERSION :
+            ++_stack_depth;
+            break;
+        case PUT_SUBS :
+            test_ref(int8(bc[0]));
+            valid_upto(_max.classes, uint16(bc[1]<< 8) | bc[2]);
+            valid_upto(_max.classes, uint16(bc[3]<< 8) | bc[4]);
+            test_context();
+            break;
+        case PUT_SUBS2 :        // not implemented
+        case PUT_SUBS3 :        // not implemented
+            break;
+        case PUT_GLYPH :
+            valid_upto(_max.classes, uint16(bc[0]<< 8) | bc[1]);
+            test_context();
+            break;
+        case PUSH_GLYPH_ATTR :
+        case PUSH_ATT_TO_GLYPH_ATTR :
+            ++_stack_depth;
+            valid_upto(_max.glyf_attrs, uint16(bc[0]<< 8) | bc[1]);
+            test_ref(int8(bc[2]));
+            break;
+        case SET_FEAT :
+            valid_upto(_max.features, bc[0]);
+            test_ref(int8(bc[1]));
+            break;
+        default:
+            failure(invalid_opcode);
+            break;
+    }
+
+    return bool(_code) ? opcode(opc) : MAX_OPCODE;
+}
+
+
+void Machine::Code::decoder::analyse_opcode(const opcode opc, const int8  * arg) throw()
+{
+  switch (opc)
+  {
+    case DELETE :
+      _code._delete = true;
+      break;
+    case ASSOC :
+      set_changed(0);
+//      for (uint8 num = arg[0]; num; --num)
+//        _analysis.set_noref(num);
+      break;
+    case PUT_GLYPH_8BIT_OBS :
+    case PUT_GLYPH :
+      _code._modify = true;
+      set_changed(0);
+      break;
+    case ATTR_SET :
+    case ATTR_ADD :
+    case ATTR_SUB :
+    case ATTR_SET_SLOT :
+    case IATTR_SET_SLOT :
+    case IATTR_SET :
+    case IATTR_ADD :
+    case IATTR_SUB :
+      set_noref(0);
+      break;
+    case NEXT :
+    case COPY_NEXT :
+      ++_slotref;
+      _contexts[_slotref] = context(uint8(_code._instr_count+1));
+      // if (_analysis.slotref > _analysis.max_ref) _analysis.max_ref = _analysis.slotref;
+      break;
+    case INSERT :
+      if (_slotref >= 0) --_slotref;
+      _code._modify = true;
+      break;
+    case PUT_SUBS_8BIT_OBS :    // slotref on 1st parameter
+    case PUT_SUBS :
+      _code._modify = true;
+      set_changed(0);
+      GR_FALLTHROUGH;
+      // no break
+    case PUT_COPY :
+      if (arg[0] != 0) { set_changed(0); _code._modify = true; }
+      set_ref(arg[0]);
+      break;
+    case PUSH_GLYPH_ATTR_OBS :
+    case PUSH_SLOT_ATTR :
+    case PUSH_GLYPH_METRIC :
+    case PUSH_ATT_TO_GATTR_OBS :
+    case PUSH_ATT_TO_GLYPH_METRIC :
+    case PUSH_ISLOT_ATTR :
+    case PUSH_FEAT :
+    case SET_FEAT :
+      set_ref(arg[1]);
+      break;
+    case PUSH_ATT_TO_GLYPH_ATTR :
+    case PUSH_GLYPH_ATTR :
+      set_ref(arg[2]);
+      break;
+    default:
+        break;
+  }
+}
+
+
+bool Machine::Code::decoder::emit_opcode(opcode opc, const byte * & bc)
+{
+    const opcode_t * op_to_fn = Machine::getOpcodeTable();
+    const opcode_t & op       = op_to_fn[opc];
+    if (op.impl[_code._constraint] == 0)
+    {
+        failure(unimplemented_opcode_used);
+        return false;
+    }
+
+    const size_t     param_sz = op.param_sz == VARARGS ? bc[0] + 1 : op.param_sz;
+
+    // Add this instruction
+    *_instr++ = op.impl[_code._constraint];
+    ++_code._instr_count;
+
+    // Grab the parameters
+    if (param_sz) {
+        memcpy(_data, bc, param_sz * sizeof(byte));
+        bc               += param_sz;
+        _data            += param_sz;
+        _code._data_size += param_sz;
+    }
+
+    // recursively decode a context item so we can split the skip into
+    // instruction and data portions.
+    if (opc == CNTXT_ITEM)
+    {
+        assert(_out_index == 0);
+        _in_ctxt_item = true;
+        _out_index = _max.pre_context + int8(_data[-2]);
+        _slotref = int8(_data[-2]);
+        _out_length = _max.rule_length;
+
+        const size_t ctxt_start = _code._instr_count;
+        byte & instr_skip = _data[-1];
+        byte & data_skip  = *_data++;
+        ++_code._data_size;
+        const byte *curr_end = _max.bytecode;
+
+        if (load(bc, bc + instr_skip))
+        {
+            bc += instr_skip;
+            data_skip  = instr_skip - byte(_code._instr_count - ctxt_start);
+            instr_skip =  byte(_code._instr_count - ctxt_start);
+            _max.bytecode = curr_end;
+
+            _out_length = 1;
+            _out_index = 0;
+            _slotref = 0;
+            _in_ctxt_item = false;
+        }
+        else
+        {
+            _out_index = 0;
+            _slotref = 0;
+            return false;
+        }
+    }
+
+    return bool(_code);
+}
+
+
+void Machine::Code::decoder::apply_analysis(instr * const code, instr * code_end)
+{
+    // insert TEMP_COPY commands for slots that need them (that change and are referenced later)
+    int tempcount = 0;
+    if (_code._constraint) return;
+
+    const instr temp_copy = Machine::getOpcodeTable()[TEMP_COPY].impl[0];
+    for (const context * c = _contexts, * const ce = c + _slotref; c < ce; ++c)
+    {
+        if (!c->flags.referenced || !c->flags.changed) continue;
+
+        instr * const tip = code + c->codeRef + tempcount;
+        memmove(tip+1, tip, (code_end - tip) * sizeof(instr));
+        *tip = temp_copy;
+        ++code_end;
+        ++tempcount;
+        _code._delete = true;
+    }
+
+    _code._instr_count = code_end - code;
+}
+
+
+inline
+bool Machine::Code::decoder::validate_opcode(const byte opc, const byte * const bc)
+{
+    if (opc >= MAX_OPCODE)
+    {
+        failure(invalid_opcode);
+        return false;
+    }
+    const opcode_t & op = Machine::getOpcodeTable()[opc];
+    if (op.impl[_code._constraint] == 0)
+    {
+        failure(unimplemented_opcode_used);
+        return false;
+    }
+    if (op.param_sz == VARARGS && bc >= _max.bytecode)
+    {
+        failure(arguments_exhausted);
+        return false;
+    }
+    const size_t param_sz = op.param_sz == VARARGS ? bc[0] + 1 : op.param_sz;
+    if (bc - 1 + param_sz >= _max.bytecode)
+    {
+        failure(arguments_exhausted);
+        return false;
+    }
+    return true;
+}
+
+
+bool Machine::Code::decoder::valid_upto(const uint16 limit, const uint16 x) const throw()
+{
+    const bool t = (limit != 0) && (x < limit);
+    if (!t) failure(out_of_range_data);
+    return t;
+}
+
+inline
+bool Machine::Code::decoder::test_ref(int8 index) const throw()
+{
+    if (_code._constraint && !_in_ctxt_item)
+    {
+        if (index > 0 || -index > _max.pre_context)
+        {
+            failure(out_of_range_data);
+            return false;
+        }
+    }
+    else
+    {
+      if (_max.rule_length == 0
+          || (_slotref + _max.pre_context + index >= _max.rule_length)
+          || (_slotref + _max.pre_context + index < 0))
+      {
+        failure(out_of_range_data);
+        return false;
+      }
+    }
+    return true;
+}
+
+bool Machine::Code::decoder::test_context() const throw()
+{
+    if (_out_index >= _out_length || _out_index < 0 || _slotref >= NUMCONTEXTS - 1)
+    {
+        failure(out_of_range_data);
+        return false;
+    }
+    return true;
+}
+
+bool Machine::Code::decoder::test_attr(attrCode) const throw()
+{
+#if 0   // This code is coming but causes backward compatibility problems.
+    if (_passtype < PASS_TYPE_POSITIONING)
+    {
+        if (attr != gr_slatBreak && attr != gr_slatDir && attr != gr_slatUserDefn
+                                 && attr != gr_slatCompRef)
+        {
+            failure(out_of_range_data);
+            return false;
+        }
+    }
+#endif
+    return true;
+}
+
+inline
+void Machine::Code::failure(const status_t s) throw() {
+    release_buffers();
+    _status = s;
+}
+
+
+inline
+void Machine::Code::decoder::set_ref(int index) throw() {
+    if (index + _slotref < 0 || index + _slotref >= NUMCONTEXTS) return;
+    _contexts[index + _slotref].flags.referenced = true;
+    if (index + _slotref > _max_ref) _max_ref = index + _slotref;
+}
+
+
+inline
+void Machine::Code::decoder::set_noref(int index) throw() {
+    if (index + _slotref < 0 || index + _slotref >= NUMCONTEXTS) return;
+    if (index + _slotref > _max_ref) _max_ref = index + _slotref;
+}
+
+
+inline
+void Machine::Code::decoder::set_changed(int index) throw() {
+    if (index + _slotref < 0 || index + _slotref >= NUMCONTEXTS) return;
+    _contexts[index + _slotref].flags.changed= true;
+    if (index + _slotref > _max_ref) _max_ref = index + _slotref;
+}
+
+
+void Machine::Code::release_buffers() throw()
+{
+    if (_own)
+        free(_code);
+    _code = 0;
+    _data = 0;
+    _own  = false;
+}
+
+
+int32 Machine::Code::run(Machine & m, slotref * & map) const
+{
+//    assert(_own);
+    assert(*this);          // Check we are actually runnable
+
+    if (m.slotMap().size() <= size_t(_max_ref + m.slotMap().context())
+        || m.slotMap()[_max_ref + m.slotMap().context()] == 0)
+    {
+        m._status = Machine::slot_offset_out_bounds;
+        return 1;
+//        return m.run(_code, _data, map);
+    }
+
+    return  m.run(_code, _data, map);
+}