fixes ordering of instructions for decoding

CMakeLists.txt

@@ -36,7 +36,8 @@ FILE(GLOB GEN_SOURCES
 
 set(LIB_SOURCES 
     src/iss/plugin/instruction_count.cpp
-	src/iss/arch/tgc_c.cpp    
+	src/iss/arch/tgc_c.cpp
+    src/iss/arch/tgc_c_decoder.cpp
 	src/vm/interp/vm_tgc_c.cpp
 	src/vm/fp_functions.cpp
     ${GEN_SOURCES}

gen_input/templates/CORENAME.h.gtl

@@ -69,6 +69,7 @@ def getCString(def val){
 #include <array>
 #include <iss/arch/traits.h>
 #include <iss/arch_if.h>
+#include <iss/arch/instruction_decoder.h>
 #include <iss/vm_if.h>
 
 namespace iss {
@@ -120,6 +121,8 @@ template <> struct traits<${coreDef.name.toLowerCase()}> {
         ${instr.instruction.name} = ${index},<%}%>
         MAX_OPCODE
     };
+
+    static std::unique_ptr<instruction_decoder<${coreDef.name.toLowerCase()}>> get_decoder();
 };
 
 struct ${coreDef.name.toLowerCase()}: public arch_if {

gen_input/templates/CORENAME_decoder.cpp.gtl

@@ -0,0 +1,86 @@
+#include "${coreDef.name.toLowerCase()}.h"
+#include <vector>
+#include <array>
+#include <cstdlib>
+#include <algorithm>
+
+namespace iss {
+namespace arch {
+namespace {
+// according to
+// https://stackoverflow.com/questions/8871204/count-number-of-1s-in-binary-representation
+#ifdef __GCC__
+constexpr size_t bit_count(uint32_t u) { return __builtin_popcount(u); }
+#elif __cplusplus < 201402L
+constexpr size_t uCount(uint32_t u) { return u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111); }
+constexpr size_t bit_count(uint32_t u) { return ((uCount(u) + (uCount(u) >> 3)) & 030707070707) % 63; }
+#else
+constexpr size_t bit_count(uint32_t u) {
+    size_t uCount = u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111);
+    return ((uCount + (uCount >> 3)) & 030707070707) % 63;
+}
+#endif
+
+using opcode_e = traits<${coreDef.name.toLowerCase()}>::opcode_e;
+
+/****************************************************************************
+ * start opcode definitions
+ ****************************************************************************/
+struct instruction_desriptor {
+    size_t length;
+    uint32_t value;
+    uint32_t mask;
+    opcode_e op;
+};
+
+const std::array<instruction_desriptor, ${instructions.size}> instr_descr = {{
+     /* entries are: size, valid value, valid mask, function ptr */<%instructions.each{instr -> %>
+    {${instr.length}, ${instr.encoding}, ${instr.mask}, opcode_e::${instr.instruction.name}},<%}%>
+}};
+
+}
+
+template<>
+struct instruction_decoder<${coreDef.name.toLowerCase()}> {
+    using opcode_e = traits<${coreDef.name.toLowerCase()}>::opcode_e;
+    using code_word_t=traits<${coreDef.name.toLowerCase()}>::code_word_t;
+
+    struct instruction_pattern {
+        uint32_t value;
+        uint32_t mask;
+        opcode_e id;
+    };
+
+    std::array<std::vector<instruction_pattern>, 4> qlut;
+
+    template<typename T>
+    unsigned decode_instruction(T);
+
+    instruction_decoder() {
+        for (auto instr : instr_descr) {
+            auto quadrant = instr.value & 0x3;
+            qlut[quadrant].push_back(instruction_pattern{instr.value, instr.mask, instr.op});
+        }
+        for(auto& lut: qlut){
+            std::sort(std::begin(lut), std::end(lut), [](instruction_pattern const& a, instruction_pattern const& b){
+                return bit_count(a.mask) < bit_count(b.mask);
+            });
+        }
+    }
+};
+
+template<>
+unsigned instruction_decoder<${coreDef.name.toLowerCase()}>::decode_instruction<traits<${coreDef.name.toLowerCase()}>::code_word_t>(traits<${coreDef.name.toLowerCase()}>::code_word_t instr){
+    auto res = std::find_if(std::begin(qlut[instr&0x3]), std::end(qlut[instr&0x3]), [instr](instruction_pattern const& e){
+        return !((instr&e.mask) ^ e.value );
+    });
+    return static_cast<unsigned>(res!=std::end(qlut[instr&0x3])? res->id : opcode_e::MAX_OPCODE);
+}
+
+
+std::unique_ptr<instruction_decoder<${coreDef.name.toLowerCase()}>> traits<${coreDef.name.toLowerCase()}>::get_decoder(){
+    return std::make_unique<instruction_decoder<${coreDef.name.toLowerCase()}>>();
+}
+
+}
+}

gen_input/templates/CORENAME_instr.yaml.gtl

@@ -12,5 +12,6 @@
 ${name}: <% instrList.findAll{!it.instruction.name.startsWith("__")}.each { %>
   - ${it.instruction.name}:
     encoding: ${it.encoding}
-    mask: ${it.mask}<%}}%>
+    mask: ${it.mask}<%if(it.attributes.size) {%>
+    attributes: ${it.attributes}<%}}}%>
 

gen_input/templates/interp/CORENAME.cpp.gtl

@@ -73,6 +73,7 @@ public:
     using addr_t      = typename super::addr_t;
     using reg_t       = typename traits::reg_t;
     using mem_type_e  = typename traits::mem_type_e;
+    using opcode_e    = typename traits::opcode_e;
     
     vm_impl();
 
@@ -94,7 +95,6 @@ protected:
 
     inline const char *name(size_t index){return traits::reg_aliases.at(index);}
 
-    typename arch::traits<ARCH>::opcode_e decode_inst_id(code_word_t instr);
     virt_addr_t execute_inst(finish_cond_e cond, virt_addr_t start, uint64_t icount_limit) override;
 
     // some compile time constants
@@ -111,13 +111,7 @@ protected:
     std::array<compile_func, LUT_SIZE_C> lut_00, lut_01, lut_10;
     std::array<compile_func, LUT_SIZE> lut_11;
 
-    struct instruction_pattern {
-        uint32_t value;
-        uint32_t mask;
-        typename arch::traits<ARCH>::opcode_e id;
-    };
-
-    std::array<std::vector<instruction_pattern>, 4> qlut;
+    std::unique_ptr<instruction_decoder<ARCH>> decoder;
 
     inline void raise(uint16_t trap_id, uint16_t cause){
         auto trap_val =  0x80ULL << 24 | (cause << 16) | trap_id;
@@ -139,42 +133,7 @@ protected:
 
     template<typename T>
     T& pc_assign(T& val){super::ex_info.branch_taken=true; return val;}
-    inline uint8_t readSpace1(typename super::mem_type_e space, uint64_t addr){
-        auto ret = super::template read_mem<uint8_t>(space, addr);
-        if(this->core.trap_state) throw 0;
-        return ret;
-    }
-    inline uint16_t readSpace2(typename super::mem_type_e space, uint64_t addr){
-        auto ret = super::template read_mem<uint16_t>(space, addr);
-        if(this->core.trap_state) throw 0;
-        return ret;
-    }
-    inline uint32_t readSpace4(typename super::mem_type_e space, uint64_t addr){
-        auto ret = super::template read_mem<uint32_t>(space, addr);
-        if(this->core.trap_state) throw 0;
-        return ret;
-    }
-    inline uint64_t readSpace8(typename super::mem_type_e space, uint64_t addr){
-        auto ret = super::template read_mem<uint64_t>(space, addr);
-        if(this->core.trap_state) throw 0;
-        return ret;
-    }
-    inline void writeSpace1(typename super::mem_type_e space, uint64_t addr, uint8_t data){
-        super::write_mem(space, addr, data);
-        if(this->core.trap_state) throw 0;
-    }
-    inline void writeSpace2(typename super::mem_type_e space, uint64_t addr, uint16_t data){
-        super::write_mem(space, addr, data);
-        if(this->core.trap_state) throw 0;
-    }
-    inline void writeSpace4(typename super::mem_type_e space, uint64_t addr, uint32_t data){
-        super::write_mem(space, addr, data);
-        if(this->core.trap_state) throw 0;
-    }
-    inline void writeSpace8(typename super::mem_type_e space, uint64_t addr, uint64_t data){
-        super::write_mem(space, addr, data);
-        if(this->core.trap_state) throw 0;
-    }
+
     template<unsigned W, typename U, typename S = typename std::make_signed<U>::type>
     inline S sext(U from) {
         auto mask = (1ULL<<W) - 1;
@@ -194,20 +153,6 @@ protected:
     ${it}<%}%>
 <%}%>
 private:
-    /****************************************************************************
-     * start opcode definitions
-     ****************************************************************************/
-    struct InstructionDesriptor {
-        size_t length;
-        uint32_t value;
-        uint32_t mask;
-        typename arch::traits<ARCH>::opcode_e op;
-    };
-
-    const std::array<InstructionDesriptor, ${instructions.size}> instr_descr = {{
-         /* entries are: size, valid value, valid mask, function ptr */<%instructions.each{instr -> %>
-        {${instr.length}, ${instr.encoding}, ${instr.mask}, arch::traits<ARCH>::opcode_e::${instr.instruction.name}},<%}%>
-    }};
 
     //static constexpr typename traits::addr_t upper_bits = ~traits::PGMASK;
     iss::status fetch_ins(virt_addr_t pc, uint8_t * data){
@@ -247,16 +192,7 @@ constexpr size_t bit_count(uint32_t u) {
 template <typename ARCH>
 vm_impl<ARCH>::vm_impl(ARCH &core, unsigned core_id, unsigned cluster_id)
 : vm_base<ARCH>(core, core_id, cluster_id) {
-    unsigned id=0;
-    for (auto instr : instr_descr) {
-        auto quadrant = instr.value & 0x3;
-        qlut[quadrant].push_back(instruction_pattern{instr.value, instr.mask, instr.op});
-    }
-    for(auto& lut: qlut){
-        std::sort(std::begin(lut), std::end(lut), [](instruction_pattern const& a, instruction_pattern const& b){
-            return bit_count(a.mask) > bit_count(b.mask);
-        });
-    }
+    decoder = traits::get_decoder();
 }
 
 inline bool is_count_limit_enabled(finish_cond_e cond){
@@ -267,19 +203,11 @@ inline bool is_jump_to_self_enabled(finish_cond_e cond){
     return (cond & finish_cond_e::JUMP_TO_SELF) == finish_cond_e::JUMP_TO_SELF;
 }
 
-template <typename ARCH>
-typename arch::traits<ARCH>::opcode_e vm_impl<ARCH>::decode_inst_id(code_word_t instr){
-    for(auto& e: qlut[instr&0x3]){
-        if(!((instr&e.mask) ^ e.value )) return e.id;
-    }
-    return arch::traits<ARCH>::opcode_e::MAX_OPCODE;
-}
-
 template <typename ARCH>
 typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e cond, virt_addr_t start, uint64_t icount_limit){
     auto pc=start;
-    auto* PC = reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::PC]);
-    auto* NEXT_PC = reinterpret_cast<uint32_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::NEXT_PC]);
+    auto* PC = reinterpret_cast<uint32_t*>(this->regs_base_ptr+traits::reg_byte_offsets[traits::PC]);
+    auto* NEXT_PC = reinterpret_cast<uint32_t*>(this->regs_base_ptr+traits::reg_byte_offsets[traits::NEXT_PC]);
     auto& trap_state = this->core.trap_state;
     auto& icount = this->core.icount;
     auto& cycle = this->core.cycle;
@@ -296,11 +224,11 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
         } else {
             if (is_jump_to_self_enabled(cond) &&
                     (instr == 0x0000006f || (instr&0xffff)==0xa001)) throw simulation_stopped(0); // 'J 0' or 'C.J 0'
-            auto inst_id = decode_inst_id(instr);
+            auto inst_id = static_cast<opcode_e>(decoder->decode_instruction(instr));
             // pre execution stuff
             if(this->sync_exec && PRE_SYNC) this->do_sync(PRE_SYNC, static_cast<unsigned>(inst_id));
             switch(inst_id){<%instructions.eachWithIndex{instr, idx -> %>
-            case arch::traits<ARCH>::opcode_e::${instr.name}: {
+            case opcode_e::${instr.name}: {
                 <%instr.fields.eachLine{%>${it}
                 <%}%>if(this->disass_enabled){
                     /* generate console output when executing the command */<%instr.disass.eachLine{%>
@@ -308,8 +236,8 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
                 }
                 // used registers<%instr.usedVariables.each{ k,v->
                 if(v.isArray) {%>
-                auto* ${k} = reinterpret_cast<uint${nativeTypeSize(v.type.size)}_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::${k}0]);<% }else{ %> 
-                auto* ${k} = reinterpret_cast<uint${nativeTypeSize(v.type.size)}_t*>(this->regs_base_ptr+arch::traits<ARCH>::reg_byte_offsets[arch::traits<ARCH>::${k}]);
+                auto* ${k} = reinterpret_cast<uint${nativeTypeSize(v.type.size)}_t*>(this->regs_base_ptr+traits::reg_byte_offsets[traits::${k}0]);<% }else{ %> 
+                auto* ${k} = reinterpret_cast<uint${nativeTypeSize(v.type.size)}_t*>(this->regs_base_ptr+traits::reg_byte_offsets[traits::${k}]);
                 <%}}%>// calculate next pc value
                 *NEXT_PC = *PC + ${instr.length/8};
                 // execute instruction<%instr.behavior.eachLine{%>

src/iss/arch/tgc_c.h

@@ -36,6 +36,7 @@
 #include <array>
 #include <iss/arch/traits.h>
 #include <iss/arch_if.h>
+#include <iss/arch/instruction_decoder.h>
 #include <iss/vm_if.h>
 
 namespace iss {
@@ -176,6 +177,8 @@ template <> struct traits<tgc_c> {
         DII = 89,
         MAX_OPCODE
     };
+
+    static std::unique_ptr<instruction_decoder<tgc_c>> get_decoder();
 };
 
 struct tgc_c: public arch_if {

src/iss/arch/tgc_c_decoder.cpp

@@ -0,0 +1,175 @@
+#include "tgc_c.h"
+#include <vector>
+#include <array>
+#include <cstdlib>
+#include <algorithm>
+
+namespace iss {
+namespace arch {
+namespace {
+// according to
+// https://stackoverflow.com/questions/8871204/count-number-of-1s-in-binary-representation
+#ifdef __GCC__
+constexpr size_t bit_count(uint32_t u) { return __builtin_popcount(u); }
+#elif __cplusplus < 201402L
+constexpr size_t uCount(uint32_t u) { return u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111); }
+constexpr size_t bit_count(uint32_t u) { return ((uCount(u) + (uCount(u) >> 3)) & 030707070707) % 63; }
+#else
+constexpr size_t bit_count(uint32_t u) {
+    size_t uCount = u - ((u >> 1) & 033333333333) - ((u >> 2) & 011111111111);
+    return ((uCount + (uCount >> 3)) & 030707070707) % 63;
+}
+#endif
+
+using opcode_e = traits<tgc_c>::opcode_e;
+
+/****************************************************************************
+ * start opcode definitions
+ ****************************************************************************/
+struct instruction_desriptor {
+    size_t length;
+    uint32_t value;
+    uint32_t mask;
+    opcode_e op;
+};
+
+const std::array<instruction_desriptor, 90> instr_descr = {{
+     /* entries are: size, valid value, valid mask, function ptr */
+    {32, 0b00000000000000000000000000110111, 0b00000000000000000000000001111111, opcode_e::LUI},
+    {32, 0b00000000000000000000000000010111, 0b00000000000000000000000001111111, opcode_e::AUIPC},
+    {32, 0b00000000000000000000000001101111, 0b00000000000000000000000001111111, opcode_e::JAL},
+    {32, 0b00000000000000000000000001100111, 0b00000000000000000111000001111111, opcode_e::JALR},
+    {32, 0b00000000000000000000000001100011, 0b00000000000000000111000001111111, opcode_e::BEQ},
+    {32, 0b00000000000000000001000001100011, 0b00000000000000000111000001111111, opcode_e::BNE},
+    {32, 0b00000000000000000100000001100011, 0b00000000000000000111000001111111, opcode_e::BLT},
+    {32, 0b00000000000000000101000001100011, 0b00000000000000000111000001111111, opcode_e::BGE},
+    {32, 0b00000000000000000110000001100011, 0b00000000000000000111000001111111, opcode_e::BLTU},
+    {32, 0b00000000000000000111000001100011, 0b00000000000000000111000001111111, opcode_e::BGEU},
+    {32, 0b00000000000000000000000000000011, 0b00000000000000000111000001111111, opcode_e::LB},
+    {32, 0b00000000000000000001000000000011, 0b00000000000000000111000001111111, opcode_e::LH},
+    {32, 0b00000000000000000010000000000011, 0b00000000000000000111000001111111, opcode_e::LW},
+    {32, 0b00000000000000000100000000000011, 0b00000000000000000111000001111111, opcode_e::LBU},
+    {32, 0b00000000000000000101000000000011, 0b00000000000000000111000001111111, opcode_e::LHU},
+    {32, 0b00000000000000000000000000100011, 0b00000000000000000111000001111111, opcode_e::SB},
+    {32, 0b00000000000000000001000000100011, 0b00000000000000000111000001111111, opcode_e::SH},
+    {32, 0b00000000000000000010000000100011, 0b00000000000000000111000001111111, opcode_e::SW},
+    {32, 0b00000000000000000000000000010011, 0b00000000000000000111000001111111, opcode_e::ADDI},
+    {32, 0b00000000000000000010000000010011, 0b00000000000000000111000001111111, opcode_e::SLTI},
+    {32, 0b00000000000000000011000000010011, 0b00000000000000000111000001111111, opcode_e::SLTIU},
+    {32, 0b00000000000000000100000000010011, 0b00000000000000000111000001111111, opcode_e::XORI},
+    {32, 0b00000000000000000110000000010011, 0b00000000000000000111000001111111, opcode_e::ORI},
+    {32, 0b00000000000000000111000000010011, 0b00000000000000000111000001111111, opcode_e::ANDI},
+    {32, 0b00000000000000000001000000010011, 0b11111110000000000111000001111111, opcode_e::SLLI},
+    {32, 0b00000000000000000101000000010011, 0b11111110000000000111000001111111, opcode_e::SRLI},
+    {32, 0b01000000000000000101000000010011, 0b11111110000000000111000001111111, opcode_e::SRAI},
+    {32, 0b00000000000000000000000000110011, 0b11111110000000000111000001111111, opcode_e::ADD},
+    {32, 0b01000000000000000000000000110011, 0b11111110000000000111000001111111, opcode_e::SUB},
+    {32, 0b00000000000000000001000000110011, 0b11111110000000000111000001111111, opcode_e::SLL},
+    {32, 0b00000000000000000010000000110011, 0b11111110000000000111000001111111, opcode_e::SLT},
+    {32, 0b00000000000000000011000000110011, 0b11111110000000000111000001111111, opcode_e::SLTU},
+    {32, 0b00000000000000000100000000110011, 0b11111110000000000111000001111111, opcode_e::XOR},
+    {32, 0b00000000000000000101000000110011, 0b11111110000000000111000001111111, opcode_e::SRL},
+    {32, 0b01000000000000000101000000110011, 0b11111110000000000111000001111111, opcode_e::SRA},
+    {32, 0b00000000000000000110000000110011, 0b11111110000000000111000001111111, opcode_e::OR},
+    {32, 0b00000000000000000111000000110011, 0b11111110000000000111000001111111, opcode_e::AND},
+    {32, 0b00000000000000000000000000001111, 0b00000000000000000111000001111111, opcode_e::FENCE},
+    {32, 0b00000000000000000000000001110011, 0b11111111111111111111111111111111, opcode_e::ECALL},
+    {32, 0b00000000000100000000000001110011, 0b11111111111111111111111111111111, opcode_e::EBREAK},
+    {32, 0b00000000001000000000000001110011, 0b11111111111111111111111111111111, opcode_e::URET},
+    {32, 0b00010000001000000000000001110011, 0b11111111111111111111111111111111, opcode_e::SRET},
+    {32, 0b00110000001000000000000001110011, 0b11111111111111111111111111111111, opcode_e::MRET},
+    {32, 0b00010000010100000000000001110011, 0b11111111111111111111111111111111, opcode_e::WFI},
+    {32, 0b01111011001000000000000001110011, 0b11111111111111111111111111111111, opcode_e::DRET},
+    {32, 0b00000000000000000001000001110011, 0b00000000000000000111000001111111, opcode_e::CSRRW},
+    {32, 0b00000000000000000010000001110011, 0b00000000000000000111000001111111, opcode_e::CSRRS},
+    {32, 0b00000000000000000011000001110011, 0b00000000000000000111000001111111, opcode_e::CSRRC},
+    {32, 0b00000000000000000101000001110011, 0b00000000000000000111000001111111, opcode_e::CSRRWI},
+    {32, 0b00000000000000000110000001110011, 0b00000000000000000111000001111111, opcode_e::CSRRSI},
+    {32, 0b00000000000000000111000001110011, 0b00000000000000000111000001111111, opcode_e::CSRRCI},
+    {32, 0b00000000000000000001000000001111, 0b00000000000000000111000001111111, opcode_e::FENCE_I},
+    {32, 0b00000010000000000000000000110011, 0b11111110000000000111000001111111, opcode_e::MUL},
+    {32, 0b00000010000000000001000000110011, 0b11111110000000000111000001111111, opcode_e::MULH},
+    {32, 0b00000010000000000010000000110011, 0b11111110000000000111000001111111, opcode_e::MULHSU},
+    {32, 0b00000010000000000011000000110011, 0b11111110000000000111000001111111, opcode_e::MULHU},
+    {32, 0b00000010000000000100000000110011, 0b11111110000000000111000001111111, opcode_e::DIV},
+    {32, 0b00000010000000000101000000110011, 0b11111110000000000111000001111111, opcode_e::DIVU},
+    {32, 0b00000010000000000110000000110011, 0b11111110000000000111000001111111, opcode_e::REM},
+    {32, 0b00000010000000000111000000110011, 0b11111110000000000111000001111111, opcode_e::REMU},
+    {16, 0b0000000000000000, 0b1110000000000011, opcode_e::CADDI4SPN},
+    {16, 0b0100000000000000, 0b1110000000000011, opcode_e::CLW},
+    {16, 0b1100000000000000, 0b1110000000000011, opcode_e::CSW},
+    {16, 0b0000000000000001, 0b1110000000000011, opcode_e::CADDI},
+    {16, 0b0000000000000001, 0b1110111110000011, opcode_e::CNOP},
+    {16, 0b0010000000000001, 0b1110000000000011, opcode_e::CJAL},
+    {16, 0b0100000000000001, 0b1110000000000011, opcode_e::CLI},
+    {16, 0b0110000000000001, 0b1110000000000011, opcode_e::CLUI},
+    {16, 0b0110000100000001, 0b1110111110000011, opcode_e::CADDI16SP},
+    {16, 0b0110000000000001, 0b1111000001111111, opcode_e::__reserved_clui},
+    {16, 0b1000000000000001, 0b1111110000000011, opcode_e::CSRLI},
+    {16, 0b1000010000000001, 0b1111110000000011, opcode_e::CSRAI},
+    {16, 0b1000100000000001, 0b1110110000000011, opcode_e::CANDI},
+    {16, 0b1000110000000001, 0b1111110001100011, opcode_e::CSUB},
+    {16, 0b1000110000100001, 0b1111110001100011, opcode_e::CXOR},
+    {16, 0b1000110001000001, 0b1111110001100011, opcode_e::COR},
+    {16, 0b1000110001100001, 0b1111110001100011, opcode_e::CAND},
+    {16, 0b1010000000000001, 0b1110000000000011, opcode_e::CJ},
+    {16, 0b1100000000000001, 0b1110000000000011, opcode_e::CBEQZ},
+    {16, 0b1110000000000001, 0b1110000000000011, opcode_e::CBNEZ},
+    {16, 0b0000000000000010, 0b1111000000000011, opcode_e::CSLLI},
+    {16, 0b0100000000000010, 0b1110000000000011, opcode_e::CLWSP},
+    {16, 0b1000000000000010, 0b1111000000000011, opcode_e::CMV},
+    {16, 0b1000000000000010, 0b1111000001111111, opcode_e::CJR},
+    {16, 0b1000000000000010, 0b1111111111111111, opcode_e::__reserved_cmv},
+    {16, 0b1001000000000010, 0b1111000000000011, opcode_e::CADD},
+    {16, 0b1001000000000010, 0b1111000001111111, opcode_e::CJALR},
+    {16, 0b1001000000000010, 0b1111111111111111, opcode_e::CEBREAK},
+    {16, 0b1100000000000010, 0b1110000000000011, opcode_e::CSWSP},
+    {16, 0b0000000000000000, 0b1111111111111111, opcode_e::DII},
+}};
+
+}
+
+template<>
+struct instruction_decoder<tgc_c> {
+    using opcode_e = traits<tgc_c>::opcode_e;
+    using code_word_t=traits<tgc_c>::code_word_t;
+
+    struct instruction_pattern {
+        uint32_t value;
+        uint32_t mask;
+        opcode_e id;
+    };
+
+    std::array<std::vector<instruction_pattern>, 4> qlut;
+
+    template<typename T>
+    unsigned decode_instruction(T);
+
+    instruction_decoder() {
+        for (auto instr : instr_descr) {
+            auto quadrant = instr.value & 0x3;
+            qlut[quadrant].push_back(instruction_pattern{instr.value, instr.mask, instr.op});
+        }
+        for(auto& lut: qlut){
+            std::sort(std::begin(lut), std::end(lut), [](instruction_pattern const& a, instruction_pattern const& b){
+                return bit_count(a.mask) > bit_count(b.mask);
+            });
+        }
+    }
+};
+
+template<>
+unsigned instruction_decoder<tgc_c>::decode_instruction<traits<tgc_c>::code_word_t>(traits<tgc_c>::code_word_t instr){
+    auto res = std::find_if(std::begin(qlut[instr&0x3]), std::end(qlut[instr&0x3]), [instr](instruction_pattern const& e){
+        return !((instr&e.mask) ^ e.value );
+    });
+    return static_cast<unsigned>(res!=std::end(qlut[instr&0x3])? res->id : opcode_e::MAX_OPCODE);
+}
+
+
+std::unique_ptr<instruction_decoder<tgc_c>> traits<tgc_c>::get_decoder(){
+    return std::make_unique<instruction_decoder<tgc_c>>();
+}
+
+}
+}