build up comp_dict

2 files changed, 220 insertions, 276 deletions

diff --git a/core.fth b/core.fth
index 00f2c87..9c6b7cf 100644
--- a/core.fth
+++ b/core.fth
@@ -1,34 +1,5 @@
-: state     [ _d 7 cells + ] literal ;
-
-: sp        [ _d cell+ ] literal ;
-: rp        [ _d 2 cells + ] literal ;
-: dp        [ _d 4 cells + ] literal ;
-
-: sp@       sp @ ;
-: rp@       rp @ cell+ ;
-: ip        [ _d 3 cells + ] literal ;
-: here      dp @ ;
 : unused    [ _d 8 cells + ] literal @ here - ;
-: base      [ _d 9 cells + ] literal ;
-: latest    _d @ ;
-
-: pick      cells cell+ sp@ + @ ;
-: >r        rp@ cell - rp !
-            rp@ cell+ @ rp@ !
-            rp@ cell+ ! ;
-: r>        rp@ @
-            rp@ cell+ rp !
-            rp@ @ swap rp@ ! ;
-: over      1 pick ;
-
-: 2dup      over over ;
-: 2over     3 pick 3 pick ;
-: 2swap     rot >r rot r> ;
 
-: +!        dup >r swap r> @ + swap ! ;
-: allot     dp +! ;
-: ,         here ! cell allot ;
-: c,        here c! 1 allot ;
 : [']       ' [ ' literal , ] ; immediate
 
 : if        ['] _jmp0 , here 0 , ; immediate
@@ -39,11 +10,6 @@
 : 2>r       ['] swap , ['] >r , ['] >r , ; immediate
 : r@        ['] r> , ['] dup , ['] >r , ; immediate
 
-: 2!        swap over ! cell+ ! ;
-: 2@        dup cell+ @ swap @ ;
-
-: <=        2dup < >r = r> or ;
-
 : _msb      [ 1 cell 8 * 1- lshift ] literal ;
 : 2/        dup 1 rshift swap 0< if _msb or then ;
 
@@ -52,16 +18,10 @@
 : min       2dup <= if drop else swap drop then ;
 : max       2dup <= if swap drop else drop then ;
 
-: aligned   cell 1- + cell 1- invert and ;
-: align     here dup aligned swap - allot ;
-
 : cr        10 emit ;
 : space     bl emit ;
 \ : spaces    begin dup 0 > while space 1- repeat drop ;
 
-: decimal   10 base ! ;
-: hex       16 base ! ;
-
 : begin     0 here ; immediate
 : while     swap 1+ swap postpone if -rot ; immediate
 : repeat    ['] _jmp , , if postpone then then ; immediate
diff --git a/forth.hpp b/forth.hpp
index 770eeb9..7357508 100644
--- a/forth.hpp
+++ b/forth.hpp
@@ -94,104 +94,6 @@ struct cS {
     }
 };
 
-template<cS Name, func Body, auto *Prev = (const word_base *)nullptr>
-struct native_word : public word_base
-{
-    constexpr static auto N = (sizeof(Name) + sizeof(cell) - 1) & ~(sizeof(cell) - 1);
-    std::array<char, N> namebuf;
-    func body;
-
-    consteval const func *get_ct(std::string_view name) const {
-        if (name == std::string_view{Name.data})
-            return &body;
-        else if constexpr (Prev != nullptr)
-            return Prev->get_ct(name);
-        else
-            return nullptr;
-    }
-
-    consteval native_word(addr flags = 0):
-        word_base{Prev, N | flags}, namebuf{}, body{Body}
-    {
-        std::copy(Name.data, Name.data + sizeof(Name), namebuf.data());
-    }
-};
-
-template<const func Prol, cS Name, cS Body, auto *Prev = (const word_base *)nullptr>
-struct comp_word : public native_word<Name, Prol, Prev>
-{
-    static constexpr std::size_t B = 
-        [] {
-            std::size_t b = 1;
-            std::string_view sv {Body.data};
-            auto sourcei = sv.find_first_not_of(" \t\r\n");
-            while (sourcei != std::string_view::npos) {
-                const auto word = word_list::parse(Body.data, sourcei);
-
-                b++;
-                if (!Prev->get_ct(word))
-                    b++;
-            }
-            return b;
-        }();
-
-    union bodyt {
-        const func *f;
-        cell c;
-    };
-
-    std::array<bodyt, B> bodybuf {};
-
-    consteval comp_word(addr flags = 0):
-        native_word<Name, Prol, Prev>{flags}
-    {
-        auto bptr = bodybuf.begin();
-        std::string_view sv {Body};
-        auto sourcei = sv.find_first_not_of(" \t\r\n");
-        while (sourcei != std::string_view::npos) {
-            const auto word = word_list::parse(Body, sourcei);
-
-            auto w = Prev->get_ct(word);
-            if (w) {
-                bptr->f = Prev->get_ct(word);
-                bptr++;
-            } else {
-                cell n;
-                std::from_chars(word.cbegin(), word.cend(), n, 10);
-
-                bptr->f = Prev->get_ct("_lit");
-                bptr++;
-                bptr->c = n;
-                bptr++;
-            }
-        }
-    }
-};
-
-template<cS Name, func Body, addr Flags, auto... Next>
-struct native_dict
-{
-    constexpr static native_word<Name, Body,
-        [] {
-            if constexpr (sizeof...(Next))
-                return &native_dict<Next...>::word;
-            else
-                return (const word_base *)nullptr;
-        }()> word {Flags};
-};
-
-template<func Prol, auto *Prev, cS Name, cS Body, addr Flags, auto... Next>
-struct comp_dict
-{
-    constexpr static comp_word<Prol, Name, Body,
-        [] {
-            if constexpr (sizeof...(Next))
-                return &comp_dict<Prol, Prev, Next...>::word;
-            else
-                return Prev;
-        }()> word {Flags};
-};
-
 struct forth : public word_list
 {
     static constexpr bool enable_exceptions = true;
@@ -330,144 +232,7 @@ struct forth : public word_list
     }
 
     template<forth** fthp>
-    static void initialize(cell *end_value)
-    {
-        assert<error::init_error>(*fthp);
-
-        static auto& fth = **fthp;
-
-        constexpr static func lit_impl = [](auto) {
-            auto ptr = std::bit_cast<cell *>(++fth.ip);
-            fth.push(*ptr);
-        };
-        auto f_dict   = [](auto) { fth.push(std::bit_cast<cell>(&fth)); };
-        auto f_add    = [](auto) { fth.top() += fth.pop(); };
-        auto f_minus  = [](auto) { fth.top() -= fth.pop(); };
-        auto f_times  = [](auto) { fth.top() *= fth.pop(); };
-        auto f_divide = [](auto) { fth.top() /= fth.pop(); };
-        auto f_mod    = [](auto) { fth.top() %= fth.pop(); };
-        auto f_bitand = [](auto) { fth.top() &= fth.pop(); };
-        auto f_bitor  = [](auto) { fth.top() |= fth.pop(); };
-        auto f_bitxor = [](auto) { fth.top() ^= fth.pop(); };
-        auto f_lshift = [](auto) { fth.top() <<= fth.pop(); };
-        auto f_rshift = [](auto) { fth.top() >>= fth.pop(); };
-        auto f_lbrac  = [](auto) { fth.compiling = false; };
-        auto f_rbrac  = [](auto) { fth.compiling = true; };
-        auto f_imm    = [](auto) {
-            const_cast<word_base *>(fth.next)->make_immediate(); };
-        auto f_lit    = [](auto) {
-            //assert<error::compile_only_word>(fth.compiling);
-            *fth.here++ = std::bit_cast<cell>(&lit_impl);
-            *fth.here++ = fth.pop(); };
-        auto f_peek = [](auto) { fth.push(*std::bit_cast<cell *>(fth.pop())); };
-        auto f_poke = [](auto) {
-            auto [p, v] = fth.pop<2>();
-            *std::bit_cast<cell *>(p) = v; };
-        auto f_cpeek = [](auto) { fth.push(*std::bit_cast<char *>(fth.pop())); };
-        auto f_cpoke = [](auto) {
-            auto [p, v] = fth.pop<2>();
-            *std::bit_cast<char *>(p) = v; };
-        auto f_swap = [](auto) { auto [a, b] = fth.pop<2>(); fth.push(a, b); };
-        auto f_drop = [](auto) { fth.pop(); };
-        auto f_dup  = [](auto) { fth.push(fth.top()); };
-        auto f_rot  = [](auto) { auto [a, b, c] = fth.pop<3>(); fth.push(b, a, c); };
-        auto f_eq   = [](auto) { auto v = fth.pop(); fth.top() = -(fth.top() == v); };
-        auto f_lt   = [](auto) { auto v = fth.pop(); fth.top() = -(fth.top() < v); };
-        auto f_tick = [](auto) {
-            auto w = fth.parse();
-
-            if (auto g = fth.get(w); g)
-                fth.push(std::bit_cast<cell>((*g)->body()));
-            else
-                fth.push(0); };
-        auto f_colon = [](auto) {
-            const auto prologue = forth::prologue<fthp>;
-            auto w = fth.parse();
-            fth.add(w);
-            *fth.here++ = std::bit_cast<cell>(prologue);
-            fth.compiling = true; };
-        auto f_semic = [](auto) { *fth.here++ = 0; fth.compiling = false; };
-        auto f_comm  = [](auto) { fth.sourcei = npos; };
-        auto f_cell  = [](auto) { fth.push(sizeof(cell)); };
-        auto f_jmp   = [](auto) {
-            auto ptr = ++fth.ip;
-            fth.ip = *std::bit_cast<func **>(ptr) - 1;
-        };
-        auto f_jmp0  = [](auto) {
-            auto ptr = ++fth.ip;
-
-            if (fth.pop() == 0)
-                fth.ip = *std::bit_cast<func **>(ptr) - 1;
-        };
-        auto f_postpone = [](auto) {
-            assert<error::compile_only_word>(fth.compiling);
-
-            auto w = fth.parse();
-            auto g = fth.get(w);
-
-            assert<error::word_not_found>(g.has_value());
-
-            *fth.here++ = std::bit_cast<cell>((*g)->body());
-        };
-
-        constexpr static auto& dict1 = native_dict<
-            cS{"_d"}, f_dict, 0,
-            cS{"_lit"}, lit_impl, 0,
-            cS{"swap"}, f_swap, 0,
-            cS{"drop"}, f_drop, 0,
-            cS{"dup"}, f_dup, 0,
-            cS{"rot"}, f_rot, 0,
-            cS{"+"}, f_add, 0,
-            cS{"-"}, f_minus, 0,
-            cS{"*"}, f_times, 0,
-            cS{"/"}, f_divide, 0,
-            cS{"mod"}, f_mod, 0,
-            cS{"and"}, f_bitand, 0,
-            cS{"or"}, f_bitor, 0,
-            cS{"xor"}, f_bitxor, 0,
-            cS{"lshift"}, f_lshift, 0,
-            cS{"rshift"}, f_rshift, 0,
-            cS{"["}, f_lbrac, word_base::immediate,
-            cS{"]"}, f_rbrac, 0,
-            cS{"immediate"}, f_imm, 0,
-            cS{"literal"}, f_lit, word_base::immediate,
-            cS{"@"}, f_peek, 0,
-            cS{"!"}, f_poke, 0,
-            cS{"c@"}, f_cpeek, 0,
-            cS{"c!"}, f_cpoke, 0,
-            cS{"="}, f_eq, 0,
-            cS{"<"}, f_lt, 0,
-            cS{"\'"}, f_tick, 0,
-            cS{":"}, f_colon, 0,
-            cS{";"}, f_semic, word_base::immediate,
-            cS{"\\"}, f_comm, word_base::immediate,
-            cS{"cell"}, f_cell, 0,
-            cS{"_jmp"}, f_jmp, 0,
-            cS{"_jmp0"}, f_jmp0, 0,
-            cS{"chars"}, [](auto) {}, 0,
-            cS{"postpone"}, f_postpone, word_base::immediate
-        >::word;
-        constexpr static auto& dict2 = comp_dict<forth::prologue<fthp>, &dict1
-            , cS{"1-"    }, cS{"1 -" }, 0
-            , cS{"1+"    }, cS{"1 +" }, 0
-            , cS{"cell+" }, cS{"cell +"}, 0
-            , cS{"cells" }, cS{"cell *"}, 0
-            , cS{"char+" }, cS{"1 +" }, 0
-            , cS{"-rot"  }, cS{"rot rot"}, 0
-            , cS{"2drop" }, cS{"drop drop"}, 0
-            , cS{"0="    }, cS{"0 ="}, 0
-            , cS{"0<"    }, cS{"0 <"}, 0
-            , cS{"<>"    }, cS{"= 0="}, 0
-            , cS{">"     }, cS{"swap <"}, 0
-            , cS{"invert"}, cS{"-1 xor"}, 0
-            , cS{"negate"}, cS{"-1 *"}, 0
-            , cS{"2*"    }, cS{"2 *"}, 0
-            , cS{"bl"    }, cS{"32"}, 0
-        >::word;
-
-        fth.next = &dict2;
-        fth.end = end_value;
-    }
+    static void initialize(cell *end_value);
 
     static auto error_string(error err) noexcept -> std::string_view {
         using enum error;
@@ -504,6 +269,104 @@ struct forth : public word_list
     std::array<func *, return_size> rstack;
 };
 
+template<cS Name, func Body, auto *Prev = (const word_base *)nullptr>
+struct native_word : public word_base
+{
+    constexpr static auto N = (sizeof(Name) + sizeof(cell) - 1) & ~(sizeof(cell) - 1);
+    std::array<char, N> namebuf;
+    func body;
+
+    consteval const func *get_ct(std::string_view name) const {
+        if (name == std::string_view{Name.data})
+            return &body;
+        else if constexpr (Prev != nullptr)
+            return Prev->get_ct(name);
+        else
+            return nullptr;
+    }
+
+    consteval native_word(addr flags = 0):
+        word_base{Prev, N | flags}, namebuf{}, body{Body}
+    {
+        std::copy(Name.data, Name.data + sizeof(Name), namebuf.data());
+    }
+};
+
+template<const func Prol, cS Name, cS Body, auto *Prev = (const word_base *)nullptr>
+struct comp_word : public native_word<Name, Prol, Prev>
+{
+    static constexpr std::size_t B =
+        [] {
+            std::size_t b = 1;
+            std::string_view sv {Body.data};
+            auto sourcei = sv.find_first_not_of(" \t\r\n");
+            while (sourcei != std::string_view::npos) {
+                const auto word = word_list::parse(Body.data, sourcei);
+
+                b++;
+                if (!Prev->get_ct(word))
+                    b++;
+            }
+            return b;
+        }();
+
+    union bodyt {
+        const func *f;
+        cell c;
+    };
+
+    std::array<bodyt, B> bodybuf {};
+
+    consteval comp_word(addr flags = 0):
+        native_word<Name, Prol, Prev>{flags}
+    {
+        auto bptr = bodybuf.begin();
+        std::string_view sv {Body};
+        auto sourcei = sv.find_first_not_of(" \t\r\n");
+        while (sourcei != std::string_view::npos) {
+            const auto word = word_list::parse(Body, sourcei);
+
+            auto w = Prev->get_ct(word);
+            if (w) {
+                bptr->f = Prev->get_ct(word);
+                bptr++;
+            } else {
+                cell n;
+                std::from_chars(word.cbegin(), word.cend(), n, 10);
+
+                bptr->f = Prev->get_ct("_lit");
+                bptr++;
+                bptr->c = n;
+                bptr++;
+            }
+        }
+    }
+};
+
+template<cS Name, func Body, addr Flags, auto... Next>
+struct native_dict
+{
+    constexpr static native_word<Name, Body,
+        [] {
+            if constexpr (sizeof...(Next))
+                return &native_dict<Next...>::word;
+            else
+                return (const word_base *)nullptr;
+        }()> word {Flags};
+};
+
+template<func Prol, auto *Prev, cS Name, cS Body, addr Flags, auto... Next>
+struct comp_dict
+{
+    constexpr static comp_word<Prol, Name, Body,
+        [] {
+            if constexpr (sizeof...(Next))
+                return &comp_dict<Prol, Prev, Next...>::word;
+            else
+                return Prev;
+        }()> word {Flags};
+};
+
 std::optional<const word_base *> word_list::get(std::string_view sv) const
 {
     for (auto lt = next; lt; lt = lt->next) {
@@ -514,6 +377,127 @@ std::optional<const word_base *> word_list::get(std::string_view sv) const
     return {};
 }
 
+template<forth** fthp>
+void forth::initialize(cell *end_value)
+{
+    assert<error::init_error>(*fthp);
+
+    static auto& fth = **fthp;
+    static auto _d = std::bit_cast<cell>(*fthp);
+
+    constexpr static func lit_impl = [](auto) {
+        auto ptr = std::bit_cast<cell *>(++fth.ip);
+        fth.push(*ptr);
+    };
+
+    constexpr static auto& dict1 = native_dict<
+          cS{"_d"   }, [](auto) { fth.push(_d); }, 0
+        , cS{"sp"   }, [](auto) { fth.push(_d + sizeof(cell)); }, 0
+        , cS{"rp"   }, [](auto) { fth.push(_d + 2 * sizeof(cell)); }, 0
+        , cS{"ip"   }, [](auto) { fth.push(_d + 3 * sizeof(cell)); }, 0
+        , cS{"dp"   }, [](auto) { fth.push(_d + 4 * sizeof(cell)); }, 0
+        , cS{"state"}, [](auto) { fth.push(_d + 7 * sizeof(cell)); }, 0
+        , cS{"base" }, [](auto) { fth.push(_d + 9 * sizeof(cell)); }, 0
+        , cS{"_lit" }, lit_impl, 0
+        , cS{"swap" }, [](auto) { auto [a, b] = fth.pop<2>(); fth.push(a, b); }, 0
+        , cS{"drop" }, [](auto) { fth.pop(); }, 0
+        , cS{"dup"  }, [](auto) { fth.push(fth.top()); }, 0
+        , cS{"rot"  }, [](auto) { auto [a, b, c] = fth.pop<3>(); fth.push(b, a, c); }, 0
+        , cS{"+"    }, [](auto) { fth.top() += fth.pop(); }, 0
+        , cS{"-"    }, [](auto) { fth.top() -= fth.pop(); }, 0
+        , cS{"*"    }, [](auto) { fth.top() *= fth.pop(); }, 0
+        , cS{"/"    }, [](auto) { fth.top() /= fth.pop(); }, 0
+        , cS{"mod"  }, [](auto) { fth.top() %= fth.pop(); }, 0
+        , cS{"and"  }, [](auto) { fth.top() &= fth.pop(); }, 0
+        , cS{"or"   }, [](auto) { fth.top() |= fth.pop(); }, 0
+        , cS{"xor"  }, [](auto) { fth.top() ^= fth.pop(); }, 0
+        , cS{"lshift"}, [](auto) { fth.top() <<= fth.pop(); }, 0
+        , cS{"rshift"}, [](auto) { fth.top() >>= fth.pop(); }, 0
+        , cS{"["    }, [](auto) { fth.compiling = false; }, word_base::immediate
+        , cS{"]"    }, [](auto) { fth.compiling = true; }, 0
+        , cS{"immediate"}, [](auto) { const_cast<word_base *>(fth.next)->make_immediate(); }, 0
+        , cS{"literal"}, [](auto) {
+            //assert<error::compile_only_word>(fth.compiling);
+            *fth.here++ = std::bit_cast<cell>(&lit_impl);
+            *fth.here++ = fth.pop(); }, word_base::immediate
+        , cS{"@"    }, [](auto) { fth.push(*std::bit_cast<cell *>(fth.pop())); }, 0
+        , cS{"!"    }, [](auto) { auto [p, v] = fth.pop<2>(); *std::bit_cast<cell *>(p) = v; }, 0
+        , cS{"c@"   }, [](auto) { fth.push(*std::bit_cast<char *>(fth.pop())); }, 0
+        , cS{"c!"   }, [](auto) { auto [p, v] = fth.pop<2>(); *std::bit_cast<char *>(p) = v; }, 0
+        , cS{"="    }, [](auto) { auto v = fth.pop(); fth.top() = -(fth.top() == v); }, 0
+        , cS{"<"    }, [](auto) { auto v = fth.pop(); fth.top() = -(fth.top() < v); }, 0
+        , cS{"\'"   }, [](auto) {
+            auto w = fth.parse();
+            auto g = fth.get(w);
+            fth.push(g ? std::bit_cast<cell>((*g)->body()) : 0); }, 0
+        , cS{":"    }, [](auto) {
+            const auto prologue = forth::prologue<fthp>;
+            auto w = fth.parse();
+            fth.add(w);
+            *fth.here++ = std::bit_cast<cell>(prologue);
+            fth.compiling = true; }, 0
+        , cS{";"    }, [](auto) { *fth.here++ = 0; fth.compiling = false; }, word_base::immediate
+        , cS{"\\"   }, [](auto) { fth.sourcei = npos; }, word_base::immediate
+        , cS{"cell" }, [](auto) { fth.push(sizeof(cell)); }, 0
+        , cS{"_jmp" }, [](auto) {
+            auto ptr = ++fth.ip;
+            fth.ip = *std::bit_cast<func **>(ptr) - 1; }, 0
+        , cS{"_jmp0"}, [](auto) {
+            auto ptr = ++fth.ip;
+            if (fth.pop() == 0)
+                fth.ip = *std::bit_cast<func **>(ptr) - 1; }, 0
+        , cS{"chars"}, [](auto) {}, 0
+        , cS{"postpone"}, [](auto) {
+            assert<error::compile_only_word>(fth.compiling);
+            auto w = fth.parse();
+            auto g = fth.get(w);
+            assert<error::word_not_found>(g.has_value());
+            *fth.here++ = std::bit_cast<cell>((*g)->body()); }, word_base::immediate
+    >::word;
+    constexpr static auto& dict2 = comp_dict<forth::prologue<fthp>, &dict1
+        , cS{"align"  }, cS{"here dup aligned swap - allot"}, 0
+        , cS{"aligned"}, cS{"cell 1- + cell 1- invert and"}, 0
+        , cS{"decimal"}, cS{"10 base !"}, 0
+        , cS{"hex"   }, cS{"16 base !"}, 0
+        , cS{"<="    }, cS{"2dup < >r = r> or"}, 0
+        , cS{"2!"    }, cS{"swap over ! cell+ !"}, 0
+        , cS{"2@"    }, cS{"dup cell+ @ swap @"}, 0
+        , cS{"c,"    }, cS{"here c! 1 allot"}, 0
+        , cS{","     }, cS{"here ! cell allot"}, 0
+        , cS{"allot" }, cS{"dp +!"}, 0
+        , cS{"+!"    }, cS{"dup >r swap r> @ + swap !"}, 0
+        , cS{"2swap" }, cS{"rot >r rot r>"}, 0
+        , cS{"2dup"  }, cS{"over over"}, 0
+        , cS{"2over" }, cS{"3 pick 3 pick"}, 0
+        , cS{">r"    }, cS{"rp@ cell - rp ! rp@ cell+ @ rp@ ! rp@ cell+ !"}, 0
+        , cS{"r>"    }, cS{"rp@ @ rp@ cell+ rp ! rp@ @ swap rp@ !"}, 0
+        , cS{"over"  }, cS{"1 pick"}, 0
+        , cS{"pick"  }, cS{"cells cell+ sp@ + @"}, 0
+        , cS{"sp@"   }, cS{"sp @"}, 0
+        , cS{"rp@"   }, cS{"rp @ cell+"}, 0
+        , cS{"here"  }, cS{"dp @"}, 0
+        , cS{"latest"}, cS{"_d @"}, 0
+        , cS{"1-"    }, cS{"1 -" }, 0
+        , cS{"1+"    }, cS{"1 +" }, 0
+        , cS{"cell+" }, cS{"cell +"}, 0
+        , cS{"cells" }, cS{"cell *"}, 0
+        , cS{"char+" }, cS{"1 +" }, 0
+        , cS{"-rot"  }, cS{"rot rot"}, 0
+        , cS{"2drop" }, cS{"drop drop"}, 0
+        , cS{"0="    }, cS{"0 ="}, 0
+        , cS{"0<"    }, cS{"0 <"}, 0
+        , cS{"<>"    }, cS{"= 0="}, 0
+        , cS{">"     }, cS{"swap <"}, 0
+        , cS{"invert"}, cS{"-1 xor"}, 0
+        , cS{"negate"}, cS{"-1 *"}, 0
+        , cS{"2*"    }, cS{"2 *"}, 0
+        , cS{"bl"    }, cS{"32"}, 0
+    >::word;
+
+    fth.next = &dict2;
+    fth.end = end_value;
+}
+
 //static_assert(offsetof(word_base, flags_len) == 1 * sizeof(cell));
 //static_assert(offsetof(forth, sp)        == 1 * sizeof(cell));
 //static_assert(offsetof(forth, rp)        == 2 * sizeof(cell));