From d9474f1d7c0c6674179fd0f27cd1c084c8227ed5 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 22 Oct 2021 12:05:41 +0200
Subject: Add interpretation function for VM

---
 src/bytecode/errors.c |  2 ++
 src/bytecode/errors.h |  5 +++++
 src/bytecode/main.c   | 13 ++++++++++---
 src/bytecode/vm.h     | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 69 insertions(+), 3 deletions(-)

(limited to 'src/bytecode')

diff --git a/src/bytecode/errors.c b/src/bytecode/errors.c
index d957cfa..c2ab77f 100644
--- a/src/bytecode/errors.c
+++ b/src/bytecode/errors.c
@@ -15,6 +15,8 @@ static const char* error_msgs[] = {
     [ERR_TOO_MANY_ARGS] = "error: too many arguments",
     [ERR_WRONG_ARG_TYPE] = "error: wrong argument type",
     [ERR_DIVISION_BY_ZERO] = "error: division by zero",
+    [ERR_PC_OOB] = "error: pc out of bounds",
+    [ERR_EMPTY_CHUNK] = "error: empty chunk",
 };
 
 static Error errors[ERR_MAX_NUMBER];
diff --git a/src/bytecode/errors.h b/src/bytecode/errors.h
index 7916f4a..c54d1f4 100644
--- a/src/bytecode/errors.h
+++ b/src/bytecode/errors.h
@@ -2,6 +2,7 @@
 #define BDL_ERRORS_H
 
 typedef enum ErrorType {
+    ERR_TYPE_OK,
     ERR_TYPE_LEXER,
     ERR_TYPE_PARSER,
     ERR_TYPE_RUNTIME,
@@ -22,6 +23,10 @@ typedef enum ErrorValue {
     ERR_TOO_MANY_ARGS,
     ERR_WRONG_ARG_TYPE,
     ERR_DIVISION_BY_ZERO,
+
+    // Bytecode interpreter.
+    ERR_PC_OOB,
+    ERR_EMPTY_CHUNK,
 } ErrorValue;
 
 typedef struct Error {
diff --git a/src/bytecode/main.c b/src/bytecode/main.c
index ca1f441..9a81aaa 100644
--- a/src/bytecode/main.c
+++ b/src/bytecode/main.c
@@ -4,8 +4,13 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "vm.h"
+//
+// Config.
+//
+
+// #define DEBUG_TRACE_EXECUTION
 
+#include "vm.h"
 #include "ops.h"
 #include "debug.h"
 #include "errors.c"
@@ -39,8 +44,10 @@ process_source(const StringView *source) {
     add_code(vm.chunk, const_idx, 1, 1);
     add_code(vm.chunk, OP_RETURN, 1, 1);
 
-    // Disassemble the chunk.
-    disassemble_chunk(vm.chunk, "test chunk");
+    vm_interpret(vm);
+    if (errors_n != 0) {
+        disassemble_chunk(vm.chunk, "test chunk");
+    }
 
     array_free(tokens);
 }
diff --git a/src/bytecode/vm.h b/src/bytecode/vm.h
index 36547cb..d53fcf9 100644
--- a/src/bytecode/vm.h
+++ b/src/bytecode/vm.h
@@ -2,14 +2,19 @@
 #define BDL_VM_H
 
 #include "types.h"
+#include "errors.h"
 #include "chunk.h"
+#include "ops.h"
+#include "debug.h"
 
 typedef struct VM {
     Chunk *chunk;
+    u8 *pc;
 } VM;
 
 VM vm_init(void);
 void vm_free(VM vm);
+void vm_interpret(VM vm);
 
 VM
 vm_init(void) {
@@ -24,4 +29,51 @@ vm_free(VM vm) {
     chunk_free(vm.chunk);
 }
 
+void
+vm_interpret(VM vm) {
+    if (vm.chunk->code == NULL || array_size(vm.chunk->code) == 0) {
+        error_push((Error){
+            .type = ERR_TYPE_RUNTIME,
+            .value = ERR_EMPTY_CHUNK,
+        });
+        return;
+    }
+
+    vm.pc = vm.chunk->code;
+    u8 *last = vm.chunk->code + array_size(vm.chunk->code);
+    while (vm.pc < last) {
+#ifdef DEBUG_TRACE_EXECUTION
+    disassemble_instruction(vm.chunk, (vm.pc - vm.chunk->code));
+#endif
+        u8 instruction = *vm.pc++;
+        switch (instruction) {
+            case OP_CONSTANT: {
+                u8 constant = *vm.pc++;
+                Object obj = vm.chunk->constants[constant];
+                display(obj);
+                printf("\n");
+            } break;
+            case OP_RETURN: {
+                return;
+            } break;
+            default: {
+                error_push((Error){
+                    .type = ERR_TYPE_RUNTIME,
+                    .value = ERR_NOT_IMPLEMENTED,
+                    .line = vm.chunk->lines[0].line,
+                    .col = vm.chunk->lines[0].col,
+                });
+                return;
+            } break;
+        }
+    }
+
+    error_push((Error){
+        .type = ERR_TYPE_RUNTIME,
+        .value = ERR_PC_OOB,
+        .line = vm.chunk->lines[0].line,
+        .col = vm.chunk->lines[0].col,
+    });
+}
+
 #endif // BDL_VM_H
-- 
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