Method emit_state_init

src/vm_codegen.cpp:111–665

    }

    void VMCodeGen::emit_state_init(X64Emitter& e, std::size_t, std::size_t data_island_size,
                                    std::uint32_t block_table_count, bool skip_regs_zero) {
        const auto& cfg = vm_.dispatcher_regs();
        const auto& st  = vm_.state_layout();

        // zero VM regs[]
        if (!skip_regs_zero) {
            const std::uint8_t zpool[7] = {rx::rax, rx::rcx, rx::rdx, rx::r8, rx::r9, rx::r10, rx::r11};
            SeedRng zero_rng(vm_.cipher_init_state() ^ 0x2E07117EU);
            
            for (std::uint8_t i = 0; i < vm_.reg_count(); ++i) {
                const std::uint8_t Z = zpool[zero_rng.pick(7)];
                e.xor_reg_reg(Z, Z);
                e.mov_mem_reg(
                    cfg.state_ptr,
                    static_cast<std::int32_t>(st.regs_base + i * 8),
                    Z,
                    true
                );
            }
        }

        // cipher state init, random per seed
        e.mov_reg_imm64(rx::rax, vm_.cipher_init_state());
        e.mov_reg_reg(cfg.cipher_state, rx::rax);
        e.mov_mem_reg(
            cfg.state_ptr,
            static_cast<std::int32_t>(st.cipher_extra) + 48,
            rx::rax,
            true
        );

        // mult/add constants into VMState slots
        std::uint64_t mult = 0, add = 0;
        switch (vm_.cipher_kind()) {
            case CipherKind::ARX:         mult = 0;                     add = vm_.cipher_k1(); break;
            case CipherKind::LcgSub:      mult = 0x5851F42D4C957F2DULL; add = vm_.cipher_k1(); break;
            case CipherKind::SBoxAdd:     mult = 0x100000001B3ULL;      add = vm_.cipher_k1(); break;
            case CipherKind::FeistelByte: mult = vm_.cipher_k1();       add = vm_.cipher_k2(); break;
        }
        constexpr std::int32_t kCipherAddOff  = 0;
        constexpr std::int32_t kCipherMultOff = 8;

        e.mov_reg_imm64(rx::rax, add);
        e.mov_mem_reg(
            cfg.state_ptr,
            static_cast<std::int32_t>(st.cipher_extra) + kCipherAddOff,
            rx::rax,
            true
        );

        e.mov_reg_imm64(rx::rax, mult);
        e.mov_mem_reg(
            cfg.state_ptr,
            static_cast<std::int32_t>(st.cipher_extra) + kCipherMultOff,
            rx::rax,
            true
        );