interpreter 5: flags packed into a struct and passed as parameters

diff --git a/interpreter5.cpp b/interpreter5.cpp
new file mode 100644 (file)
index 0000000..ff400c6
--- /dev/null
+++ b/interpreter5.cpp
@@ -0,0 +1,155 @@
+#include "bytecode.h"
+#include <utility>
+#include "interpreter.h"
+
+namespace interpreter5
+{
+
+    struct Flags
+    {
+        unsigned int zero:16;
+        unsigned int negative:16;
+    };
+
+    struct CpuState
+    {
+        int32_t regs[16] = {0};
+        uint32_t cycle_count = 0;
+    };
+
+
+    struct ReturnException
+    {
+    };
+
+
+    struct ReturnVal
+    {
+        uint8_t *pc;
+        Flags flags;
+    };
+
+
+#define PARAMS CpuState *state, uint8_t *pc, Flags flags
+#define ARGS state, pc, flags
+#define RETURN_VAL {pc, flags}
+
+    ReturnVal op_return(PARAMS)
+    {
+        state->cycle_count += 1;
+        throw ReturnException();
+    }
+
+    ReturnVal op_add(PARAMS)
+    {
+        uint8_t reg = *pc++;
+        uint8_t dest = reg>>4, src = reg & 0xf;
+
+        int32_t v = state->regs[dest];
+        v += state->regs[src];
+
+        flags.zero = (v == 0);
+        flags.negative = (v < 0);
+        state->regs[dest] = v;
+        state->cycle_count += 2;
+        return RETURN_VAL;
+    }
+
+    ReturnVal op_sub(PARAMS)
+    {
+        uint8_t reg = *pc++;
+        uint8_t dest = reg>>4, src = reg & 0xf;
+
+        int32_t v = state->regs[dest];
+        v -= state->regs[src];
+
+        flags.zero = (v == 0);
+        flags.negative = (v < 0);
+        state->regs[dest] = v;
+        state->cycle_count += 2;
+        return RETURN_VAL;
+    }
+
+    ReturnVal op_mov(PARAMS)
+    {
+        uint8_t reg = *pc++;
+        uint8_t dest = reg>>4, src = reg & 0xf;
+
+        state->regs[dest] = state->regs[src];
+        state->cycle_count += 2;
+        return RETURN_VAL;
+
+    }
+
+    ReturnVal op_movi(PARAMS)
+    {
+        uint8_t reg = *pc++;
+        uint8_t dest = reg>>4;
+
+        int32_t imm = *(int32_t *)pc;
+        pc += 4;
+
+        state->regs[dest] = imm;
+        state->cycle_count += 6;
+        return RETURN_VAL;
+
+    }
+
+    ReturnVal op_b(PARAMS)
+    {
+        int8_t rel = *pc++;
+        pc += rel;
+        state->cycle_count += 2;
+        return RETURN_VAL;
+    }
+
+    ReturnVal op_bnz(PARAMS)
+    {
+        int8_t rel = *pc++;
+        if(!flags.zero)
+        {
+            pc += rel;
+        }
+        state->cycle_count += 2;
+        return RETURN_VAL;
+    }
+
+    ReturnVal (*dispatch_table[])(PARAMS) =
+    {
+        op_return,
+        op_add,
+        op_sub,
+        op_mov,
+        op_movi,
+        op_b,
+        op_bnz
+    };
+
+    std::pair<int32_t, uint32_t> interpreter_run(uint8_t *program, int32_t param)
+    {
+        CpuState local_state;
+        CpuState *state = &local_state;
+        uint8_t *pc = program;
+        state->regs[X0] = param;
+        state->cycle_count = 0;
+        Flags flags = {0, 0};
+        try
+        {
+            while(true)
+            {
+                uint8_t opcode = *pc++;
+                ReturnVal ret = dispatch_table[opcode](ARGS);
+                pc = ret.pc;
+                flags = ret.flags;
+            }
+
+
+        } catch(ReturnException ex)
+        {
+            return std::make_pair(state->regs[X0], state->cycle_count);
+        }
+
+    }
+
+
+}

diff --git a/interpreter_trials.cpp b/interpreter_trials.cpp
index 00dc05d4bd3c12b6b90fcf50fca805dd540cabd3..c09bdf0d4427cb17f2c522cc279038a16cbfcd10 100644 (file)
--- a/interpreter_trials.cpp
+++ b/interpreter_trials.cpp
@@ -52,4 +52,12 @@ static void interpreter4_fibonacci(benchmark::State& state) {
 }
 BENCHMARK(interpreter4_fibonacci);
 
+static void interpreter5_fibonacci(benchmark::State& state) {
+    for (auto _ : state)
+    {
+        run(interpreter5::interpreter_run);
+    }
+}
+BENCHMARK(interpreter5_fibonacci);
+
 BENCHMARK_MAIN();

diff --git a/meson.build b/meson.build
index 308f090fe20155a05002c2d9c928927e46f38aa7..5440d8c70914b76366f39f0320a3a1956fddd749 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -11,4 +11,5 @@ executable('interpreter_trials',
        'interpreter2.cpp',
        'interpreter3.cpp',
        'interpreter4.cpp',
+       'interpreter5.cpp',
                                        dependencies : benchmark_dep)