diff --git a/src/VM/VM.c b/src/VM/VM.c
index b505cf2..1c9105e 100644
--- a/src/VM/VM.c
+++ b/src/VM/VM.c
@@ -49,7 +49,7 @@ i32 VM_boot(VM* vm){
     while (vm->current_pos < vm->data_size){
         u8 opcode = vm->data[vm->current_pos];
 
-        const Instruction* instr = Instruction_getFromOpcode(opcode);
+        const Instruction* instr = Instruction_getByOpcode(opcode);
         // printfe("[at 0x%x] %02X %s\n", (u32)vm->current_pos, opcode, instr->name);
         if(instr == NULL){
             VM_setError(vm, "unknown opcode %02X", opcode);
diff --git a/src/compiler/AST.c b/src/compiler/AST.c
new file mode 100644
index 0000000..6a7ebf3
--- /dev/null
+++ b/src/compiler/AST.c
@@ -0,0 +1,5 @@
+#include "AST.h"
+
+List_define(Argument);
+List_define(Operation);
+List_define(DataDefinition);
\ No newline at end of file
diff --git a/src/compiler/AST.h b/src/compiler/AST.h
index ad37846..74b75cb 100644
--- a/src/compiler/AST.h
+++ b/src/compiler/AST.h
@@ -7,27 +7,37 @@ typedef enum ArgumentType {
     ArgumentType_NoArgument,
     ArgumentType_Register,
     ArgumentType_ConstValue,
-    ArgumentType_Name,
+    ArgumentType_DataName,
     ArgumentType_NamedDataPointer,
     ArgumentType_NamedDataSize,
-};
+} ArgumentType;
 
 typedef struct Argument {
     ArgumentType type;
     u32 value;
 } Argument;
 
+List_declare(Argument);
+
+typedef struct Operation {
+    Opcode op;
+    List_Argument args;
+} Operation;
+
+List_declare(Operation);
+
 typedef struct DataDefinition {
     u8 element_size;
-    u16 size;
-    void* data;
+    u16 count;
     cstr name;
-};
+    void* data;
+} DataDefinition;
 
 List_declare(DataDefinition);
 
 typedef struct AST {
-    DataDefinition
+    List_DataDefinition data;
+    List_Operation operations;
 } AST;
 
 /*
diff --git a/src/compiler/compiler.c b/src/compiler/compiler.c
index 79bb79a..427cc8f 100644
--- a/src/compiler/compiler.c
+++ b/src/compiler/compiler.c
@@ -1,78 +1,19 @@
-#include "Lexer.h"
+#include "Compiler_internal.h"
 
-List_define(Token);
-
-CodePos Lexer_getLineAndColumn(Lexer* cmp, u32 pos){
-    u32 prev_lines_len = 0;
-    if(pos >= cmp->code_len)
-        return CodePos_create(0, 0);
-    
-    for(u32 i = 0; i < cmp->line_lengths.len; i++){
-        u32 line_len = cmp->line_lengths.data[i];
-        if(prev_lines_len + line_len > pos)
-            return CodePos_create(i + 1, pos + 1 - prev_lines_len);
-        prev_lines_len += line_len;
-    }
-
-    return CodePos_create(0, 0);
+#define setError(FORMAT, ...) {\
+    completeLine(cmp);\
+    Compiler_setError(cmp, FORMAT, ##__VA_ARGS__);\
 }
 
-static void completeLine(Lexer* cmp){
-    List_u32_push(&cmp->line_lengths, cmp->column);
-    cmp->column = 0;
-}
-
-void _Lexer_setError(Lexer* cmp, cstr context, cstr format, ...){
-    completeLine(cmp);
-    // happens at the end of file
-    if(cmp->pos >= cmp->code_len)
-        cmp->pos = cmp->code_len - 1;
-    char position_str[32];
-    CodePos code_pos = Lexer_getLineAndColumn(cmp, cmp->pos);
-    sprintf(position_str, "[at %u:%u][", code_pos.line, code_pos.column);
-    char* real_format = strcat_malloc(position_str, context, "] ", format);
-    va_list argv;
-    va_start(argv, format);
-    char* NULLABLE(buf) = vsprintf_malloc(512, real_format, argv);
-    va_end(argv);
-    free(real_format);
-    if(buf == NULL){
-        buf = malloc(16);
-        strcpy(buf, "SPRINTF FAILED");
-    }
-    cmp->state = LexerState_Error;
-    cmp->error_message = buf;
-}
-
-
-#define setError(FORMAT, ...) Lexer_setError(cmp, FORMAT, ##__VA_ARGS__)
-
-#define returnError(FORMAT, ...) {\
-    setError(FORMAT, ##__VA_ARGS__);\
-    return false;\
-}
-
-#define returnErrorIf(STATEMENT, FORMAT, ...) if(STATEMENT) returnError(FORMAT, ##__VA_ARGS__)
-
-#define returnErrorIf_auto(STATEMENT) returnErrorIf(STATEMENT, #STATEMENT)
-
 #define Error_unexpectedCharacter(C) "unexpected character '%c'", C
 #define Error_endOfFile "unexpected end of file"
 
-void Lexer_init(Lexer* cmp){
-    memset(cmp, 0, sizeof(Lexer));
-    cmp->state = LexerState_Initial;
-    cmp->tokens = List_Token_alloc(4096);
-    cmp->line_lengths = List_u32_alloc(1024);
+static void completeLine(Compiler* cmp){
+    List_u32_push(&cmp->line_lengths, cmp->column);
+    cmp->column = 0;
 }
 
-void Lexer_free(Lexer* cmp){
-    free(cmp->code);
-    free(cmp->tokens.data);
-    free(cmp->line_lengths.data);
-}
-
-static void readCommentSingleLine(Lexer* cmp){
+static void readCommentSingleLine(Compiler* cmp){
     char c; // '/'
     Token tok = Token_construct(TokenType_SingleLineComment, cmp->pos - 1, 0);
     cmp->column++;
@@ -97,7 +38,7 @@ static void readCommentSingleLine(Lexer* cmp){
     List_Token_push(&cmp->tokens, tok);
 }
 
-static void readCommentMultiLine(Lexer* cmp){
+static void readCommentMultiLine(Compiler* cmp){
     char c; // '*'
     Token tok = Token_construct(TokenType_MultiLineComment, cmp->pos - 1, 0);
     cmp->column++;
@@ -122,7 +63,7 @@ static void readCommentMultiLine(Lexer* cmp){
     setError(Error_endOfFile);
 }
 
-static void readComment(Lexer* cmp){
+static void readComment(Compiler* cmp){
     char c; // '/'
     if(cmp->pos + 1 == cmp->code_len){
         setError(Error_endOfFile);
@@ -144,7 +85,7 @@ static void readComment(Lexer* cmp){
     else setError(Error_unexpectedCharacter(c));
 }
 
-static void readLabel(Lexer* cmp){
+static void readLabel(Compiler* cmp){
     char c; // '.'
     cmp->pos++;
     cmp->column++;
@@ -179,16 +120,27 @@ static void readLabel(Lexer* cmp){
     else setError(Error_endOfFile);
 }
 
-static void readArguments(Lexer* cmp){
+static void readArguments(Compiler* cmp){
     char c; // space
-    cmp->pos++;
-    cmp->column++;
-    Token tok = Token_construct(TokenType_Argument, cmp->pos, 0);
-    
+    Token tok = Token_construct(TokenType_Unset, cmp->pos, 0);
+    char quot = '\0'; // quotation character of a string value
+
     while(cmp->pos < cmp->code_len){
         c = cmp->code[cmp->pos];
+
+        // string argument reading
+        if(quot != '\0'){
+            if(c == quot && cmp->code[cmp->pos - 1] != '\\'){
+                quot = '\0';
+            }
+            else if(c == '\r' || c == '\n'){
+                setError("line end reached but string hasn't been closed yet");
+                return;
+            }
+        }
+
         // end of line
-        if(c == '\r' || c == '\n' || c == ';'){
+        else if(c == '\r' || c == '\n' || c == ';'){
             tok.length = cmp->pos - tok.begin;
             if(tok.length > 0)
                 List_Token_push(&cmp->tokens, tok);
@@ -197,13 +149,30 @@ static void readArguments(Lexer* cmp){
         }
 
         // new argument begins
-        if(c == ' ' || c == '\t'){
+        else if(c == ' ' || c == '\t'){
             tok.length = cmp->pos - tok.begin;
             if(tok.length > 0)
                 List_Token_push(&cmp->tokens, tok);
-            tok.begin = cmp->pos + 1;
+            tok = Token_construct(TokenType_Unset, cmp->pos + 1, 0);
+        }
+
+        else if(tok.type == TokenType_Unset){
+            if(c == '\''){
+                tok.type = TokenType_Char;
+                quot = c;
+            }
+            else if(c == '"'){
+                tok.type = TokenType_String;
+                quot = c;
+            }
+            else if(c == '@')
+                tok.type = TokenType_NamedDataPointer;
+            else if(c == '#')
+                tok.type = TokenType_NamedDataSize;
+            else if(isDigit(c))
+                tok.type = TokenType_Number;
+            else tok.type = TokenType_Name;
         }
-        
 
         cmp->column++;
         cmp->pos++;
@@ -215,7 +184,7 @@ static void readArguments(Lexer* cmp){
         List_Token_push(&cmp->tokens, tok);
 }
 
-static void readInstruction(Lexer* cmp){
+static void readInstruction(Compiler* cmp){
     Token tok = Token_construct(TokenType_Instruction, cmp->pos, 0);
     cmp->pos++;
     cmp->column++;
@@ -252,86 +221,9 @@ static void readInstruction(Lexer* cmp){
     List_Token_push(&cmp->tokens, tok);
 }
 
-static void readChar(Lexer* cmp){
-    Token tok = Token_construct(TokenType_Char, cmp->pos, 0);
-    cmp->pos++;
-    cmp->column++;
-    
-    while(cmp->pos < cmp->code_len){
-        char c = cmp->code[cmp->pos];
-        // end of line
-        if(c == '\r' || c == '\n'){
-            setError(Error_unexpectedCharacter(cmp->code[--cmp->pos]));
-            return;
-        }
-
-        if(c == '\''){
-            tok.length = cmp->pos - tok.begin + 1;
-            List_Token_push(&cmp->tokens, tok);
-            return;
-        }
-
-        cmp->column++;
-        cmp->pos++;
-    }
-    
-    // end of file
-    setError(Error_endOfFile);
-}
-
-static void readString(Lexer* cmp){
-    Token tok = Token_construct(TokenType_String, cmp->pos, 0);
-    cmp->pos++;
-    cmp->column++;
-    
-    while(cmp->pos < cmp->code_len){
-        char c = cmp->code[cmp->pos];
-        // end of line
-        if(c == '\r' || c == '\n'){
-            setError(Error_unexpectedCharacter(cmp->code[--cmp->pos]));
-            return;
-        }
-
-        if(c == '"'){
-            tok.length = cmp->pos - tok.begin + 1;
-            List_Token_push(&cmp->tokens, tok);
-            return;
-        }
-
-        cmp->column++;
-        cmp->pos++;
-    }
-    
-    // end of file
-    setError(Error_endOfFile);
-}
-
-static void readNumber(Lexer* cmp){
-    Token tok = Token_construct(TokenType_Number, cmp->pos, 0);
-    cmp->pos++;
-    cmp->column++;
-    
-    while(cmp->pos < cmp->code_len){
-        char c = cmp->code[cmp->pos];
-
-        if(c == '\r' || c == '\n' || c == ' ' || c == '\t' || c == ',' || c == ';'){
-            tok.length = cmp->pos - tok.begin;
-            List_Token_push(&cmp->tokens, tok);
-            return;
-        }
-
-        cmp->column++;
-        cmp->pos++;
-    }
-    
-    // end of file
-    tok.length = cmp->pos - tok.begin;
-    List_Token_push(&cmp->tokens, tok);
-}
-
-static bool lex(Lexer* cmp){
-    returnErrorIf_auto(cmp->state != LexerState_Initial);
-    cmp->state = LexerState_Lexing;
+bool Compiler_lex(Compiler* cmp){
+    returnErrorIf_auto(cmp->state != CompilerState_Initial);
+    cmp->state = CompilerState_Lexing;
     cmp->column = 1;
 
     while(cmp->pos < cmp->code_len){
@@ -348,23 +240,15 @@ static bool lex(Lexer* cmp){
             case '.':
                 readLabel(cmp);
                 break;
-            case '"':
-                readString(cmp);
-                break;
-            case '\'':
-                readChar(cmp);
-                break;
             default:
                 // try read instruction
                 if(isAlphabeticalLower(c) || isAlphabeticalUpper(c))
                     readInstruction(cmp);
-                else if(isDigit(c))
-                    readNumber(cmp);
                 else returnError(Error_unexpectedCharacter(c));
                 break;
         }
 
-        if(cmp->state == LexerState_Error)
+        if(cmp->state == CompilerState_Error)
             return false;
         
         c = cmp->code[cmp->pos];
@@ -377,94 +261,3 @@ static bool lex(Lexer* cmp){
     completeLine(cmp);
     return true;
 }
-
-static bool parse(Lexer* cmp){
-    returnErrorIf_auto(cmp->state != LexerState_Lexing);
-    cmp->state = LexerState_Parsing;
-
-    return true;
-}
-static bool compile(Lexer* cmp, FILE* f){
-    returnErrorIf_auto(cmp->state != LexerState_Parsing);
-    cmp->state = LexerState_Compiling;
-
-    return true;
-}
-
-bool Lexer_compileTasm(Lexer* cmp, cstr source_file_name, cstr out_file_name, bool debug){
-    FILE* f = fopen(source_file_name, "rb");
-    if(f == NULL)
-        returnError("ERROR: can't open file '%s'", source_file_name);
-    
-    List_u8 buf = List_u8_alloc(64 * 1024);
-    int ret;
-    while((ret = fgetc(f)) != EOF) {
-        List_u8_push(&buf, ret);
-    }
-    if(ferror(f)){
-        free(buf.data);
-        fclose(f);
-        returnError("can't read file '%s'", source_file_name);
-    }
-    fclose(f);
-
-    if(buf.len == 0){
-        free(buf.data);
-        fclose(f);
-        returnError("soucre file is empty");
-    }
-
-    cmp->code = (char*)buf.data;
-    cmp->code_len = buf.len;
-    List_u8_push(&buf, 0);
-
-    f = fopen(out_file_name, "wb");
-    if(f == NULL){
-        free(buf.data);
-        returnError("ERROR: can't open file '%s'", out_file_name);
-    }
-
-    if(debug){
-        printf("----------------------------------[%s]---------------------------------\n", source_file_name);
-        fputs(cmp->code, stdout);
-        fputc('\n', stdout);
-    }
-    
-    bool success = lex(cmp);
-    if(debug){
-        printf("------------------------------------[lines]-----------------------------------\n");
-        for(u32 i = 0; i < cmp->line_lengths.len; i++){
-            printf("[%u] length: %u\n", i+1, cmp->line_lengths.data[i]);
-        }
-        printf("------------------------------------[tokens]-----------------------------------\n");
-        for(u32 i = 0; i < cmp->tokens.len; i++){
-            Token t = cmp->tokens.data[i];
-            CodePos pos = Lexer_getLineAndColumn(cmp, t.begin);
-            char* tokstr = malloc(4096);
-            strncpy(tokstr, cmp->code + t.begin, t.length);
-            tokstr[t.length] = 0;
-            printf("[l:%3u, c:%3u] %s '%s'\n", 
-                pos.line, pos.column,
-                TokenType_toString(t.type), tokstr);
-            free(tokstr);
-        }
-    }
-    if(!success){
-        fclose(f);
-        return false;
-    }
-
-    success = parse(cmp);
-    if(!success){
-        fclose(f);
-        return false;
-    }
-
-    success = compile(cmp, f);
-    fclose(f);
-    if(success){
-        cmp->state = LexerState_Success;
-    }
-    
-    return success;
-}
diff --git a/src/compiler/compiler.h b/src/compiler/compiler.h
index 5390407..cb5485b 100644
--- a/src/compiler/compiler.h
+++ b/src/compiler/compiler.h
@@ -1,48 +1,32 @@
 #pragma once
 #include "../std.h"
 #include "../collections/List.h"
-#include "token.h"
+#include "Token.h"
 #include "AST.h"
 
-List_declare(Token);
+typedef enum CompilerState {
+    CompilerState_Initial,
+    CompilerState_Lexing,
+    CompilerState_Parsing,
+    CompilerState_Compiling,
+    CompilerState_Error,
+    CompilerState_Success
+} CompilerState;
 
-typedef enum LexerState {
-    LexerState_Initial,
-    LexerState_Lexing,
-    LexerState_Parsing,
-    LexerState_Compiling,
-    LexerState_Error,
-    LexerState_Success
-} LexerState;
-
-typedef struct Lexer {
+typedef struct Compiler {
     char* code;
     u32 code_len;
     u32 column;     // > 0 if code parsing started
     u32 pos;
-    LexerState state;
+    CompilerState state;
     NULLABLE(char* error_message);
     List_Token tokens;
     List_u32 line_lengths;
-} Lexer;
+} Compiler;
 
-void Lexer_init(Lexer* cmp);
-void Lexer_free(Lexer* cmp);
+void Compiler_init(Compiler* cmp);
+void Compiler_free(Compiler* cmp);
 
 /// @brief compile assembly language code to machine code
 /// @return true if no errors, false if any error occured (check cmp->error_message)
-bool Lexer_compileTasm(Lexer* cmp, cstr source_file_name, cstr out_file_name, bool debug);
-
-#define Lexer_setError(cmp, format, ...) _Lexer_setError(cmp, __func__, format ,##__VA_ARGS__)
-void _Lexer_setError(Lexer* cmp, cstr context, cstr format, ...) __attribute__((__format__(__printf__, 3, 4)));
-
-typedef struct CodePos {
-    u32 line; // 0 on error
-    u32 column; // 0 on error
-} CodePos;
-
-#define CodePos_create(L, C) ((CodePos){ .line = L, .column = C })
-
-/// @param pos index in code buffer
-CodePos Lexer_getLineAndColumn(Lexer* cmp, u32 pos);
-
+bool Compiler_compile(Compiler* cmp, cstr source_file_name, cstr out_file_name, bool debug);
diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index e69de29..4e79443 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -0,0 +1,27 @@
+#include "Compiler.h"
+
+void _Compiler_setError(Compiler* cmp, cstr context, cstr format, ...) __attribute__((__format__(__printf__, 3, 4)));
+
+#define Compiler_setError(cmp, format, ...) _Compiler_setError(cmp, __func__, format ,##__VA_ARGS__)
+
+#define returnError(FORMAT, ...) {\
+    setError(FORMAT, ##__VA_ARGS__);\
+    return false;\
+}
+
+#define returnErrorIf(STATEMENT, FORMAT, ...) if(STATEMENT) returnError(FORMAT, ##__VA_ARGS__)
+
+#define returnErrorIf_auto(STATEMENT) returnErrorIf(STATEMENT, #STATEMENT)
+
+typedef struct CodePos {
+    u32 line; // 0 on error
+    u32 column; // 0 on error
+} CodePos;
+
+#define CodePos_create(L, C) ((CodePos){ .line = L, .column = C })
+
+/// @param pos index in code buffer
+CodePos Compiler_getLineAndColumn(Compiler* cmp, u32 pos);
+
+bool Compiler_lex(Compiler* cmp);
+bool Compiler_parse(Compiler* cmp);
diff --git a/src/compiler/parser.c b/src/compiler/parser.c
index 5de8c9d..12b2fa6 100644
--- a/src/compiler/parser.c
+++ b/src/compiler/parser.c
@@ -1,3 +1,12 @@
-#include "compiler.h"
+#include "Compiler_internal.h"
 
-List_define(DataDefinition);
+#define setError(FORMAT, ...) {\
+    Compiler_setError(cmp, FORMAT, ##__VA_ARGS__);\
+}
+
+bool Compiler_parse(Compiler* cmp){
+    returnErrorIf_auto(cmp->state != CompilerState_Lexing);
+    cmp->state = CompilerState_Parsing;
+
+    return true;
+}
diff --git a/src/compiler/token.c b/src/compiler/token.c
index e5f7961..cf62d87 100644
--- a/src/compiler/token.c
+++ b/src/compiler/token.c
@@ -1,19 +1,19 @@
-#include "token.h"
+#include "Token.h"
+
+List_define(Token);
 
 static cstr _TokenType_str[] = {
     "Unset",
     "SingleLineComment",
     "MultiLineComment",
+    "Instruction",
     "Label",
-    "DataDefinition",
     "Number",
     "Char",
     "String",
-    "Instruction",
-    "Register",
-    "DataType",
-    "DataPointer",
-    "DataSize"
+    "Name",
+    "NamedDataPointer",
+    "NamedDataSize"
 };
 
 cstr TokenType_toString(TokenType t){
diff --git a/src/compiler/token.h b/src/compiler/token.h
index a5fee2c..2a4faad 100644
--- a/src/compiler/token.h
+++ b/src/compiler/token.h
@@ -1,20 +1,19 @@
 #pragma once
 #include "../std.h"
+#include "../collections/List.h"
 
 typedef enum TokenType {
-    TokenType_Unset,
-    TokenType_SingleLineComment,
-    TokenType_MultiLineComment,
-    TokenType_Label,
-    TOkenType_DataDefinition,
-    TokenType_Number,
-    TokenType_Char,
-    TokenType_String,
-    TokenType_Instruction,
-    TokenType_Register,
-    TokenType_DataType,
-    TokenType_DataPointer,
-    TokenType_DataSize
+    TokenType_Unset,                // initial value
+    TokenType_SingleLineComment,    // //comment
+    TokenType_MultiLineComment,     // /* comment */
+    TokenType_Instruction,          // abc
+    TokenType_Label,                // .abc:
+    TokenType_Number,               // 0123
+    TokenType_Char,                 // 'A'
+    TokenType_String,               // "aaaa"
+    TokenType_Name,                 // xyz
+    TokenType_NamedDataPointer,     // @xyz
+    TokenType_NamedDataSize         // #xyz
 } TokenType;
 
 cstr TokenType_toString(TokenType t);
@@ -25,4 +24,6 @@ typedef struct Token {
     TokenType type : 8; // type of token (8 bits)
 } Token;
 
+List_declare(Token);
+
 #define Token_construct(TYPE, BEGIN, END) ((Token){ .type = TYPE, .begin = BEGIN, .length = END })
diff --git a/src/instructions/instructions.c b/src/instructions/instructions.c
index 1431253..f6ccedc 100644
--- a/src/instructions/instructions.c
+++ b/src/instructions/instructions.c
@@ -29,7 +29,7 @@ const Instruction instructions[] = {
     // Instruction_construct(CALL),
 };
 
-const Instruction* Instruction_getFromOpcode(Opcode opcode){
+const Instruction* Instruction_getByOpcode(Opcode opcode){
     if(opcode >= ARRAY_SIZE(instructions))
         return NULL;
     
diff --git a/src/instructions/instructions.h b/src/instructions/instructions.h
index 7f06caa..1c8f054 100644
--- a/src/instructions/instructions.h
+++ b/src/instructions/instructions.h
@@ -33,4 +33,4 @@ typedef struct Instruction {
 /// @brief get instruction info from table
 /// @param opcode any byte
 /// @return ptr to struct or NULL
-const Instruction* NULLABLE(Instruction_getFromOpcode)(Opcode opcode);
+const Instruction* NULLABLE(Instruction_getByOpcode)(Opcode opcode);
diff --git a/src/main.c b/src/main.c
index 65382cd..8393dfc 100644
--- a/src/main.c
+++ b/src/main.c
@@ -33,7 +33,7 @@ i32 main(const i32 argc, cstr* argv){
         }
         else if(arg_is("-op") || arg_is("--opcodes")){
             for(u8 opcode = 0; opcode < 255; opcode++){
-                const Instruction* instr = Instruction_getFromOpcode(opcode);
+                const Instruction* instr = Instruction_getByOpcode(opcode);
                 if(instr != NULL){
                     printf("%02X %s\n", opcode, instr->name);
                 }
@@ -134,7 +134,7 @@ i32 bootFromImage(cstr image_file){
 i32 compileSources(cstr source_file, cstr out_file){
     Compiler cmp;
     Compiler_init(&cmp);
-    bool success = Compiler_compileTasm(&cmp, source_file, out_file, true);
+    bool success = Compiler_compile(&cmp, source_file, out_file, true);
     Compiler_free(&cmp);
     if(!success){
         if(cmp.error_message){