diff --git a/include/Asm/asm.h b/include/Asm/asm.h
index eab8e01..6ef97d6 100644
--- a/include/Asm/asm.h
+++ b/include/Asm/asm.h
@@ -41,6 +41,7 @@ char const * as_get_format_name(As * as);
 
 /* useful */
 int as_decode(As * as, char const * buffer, size_t size);
+int as_decode_file(As * as, char const * filename, FILE * fp);
 int as_parse(As * as, char const * infile, char const * outfile);
 
 int as_open(As * as, char const * outfile);
diff --git a/src/arch.c b/src/arch.c
index d8c4003..f380ffd 100644
--- a/src/arch.c
+++ b/src/arch.c
@@ -63,6 +63,7 @@ struct _Arch
 /* prototypes */
 /* callbacks */
 static char const * _arch_get_filename(Arch * arch);
+static ssize_t _arch_read(Arch * arch, void * buf, size_t size);
 static ssize_t _arch_read_buffer(Arch * arch, void * buf, size_t size);
 static ssize_t _arch_write(Arch * arch, void const * buf, size_t size);
 
@@ -489,6 +490,23 @@ static void _decode_print(ArchInstructionCall * call)
 }
 
 
+/* arch_decode_at */
+int arch_decode_at(Arch * arch, off_t offset, size_t size, off_t base)
+{
+	int ret;
+
+	if(arch->fp == NULL)
+		return -error_set_code(1, "%s", strerror(ENOSYS));
+	if(fseek(arch->fp, offset, SEEK_SET) != 0)
+		return -error_set_code(1, "%s", strerror(errno));
+	/* FIXME implement size, consider offset and base */
+	if((ret = arch_decode(arch)) == 0
+			&& fseek(arch->fp, offset + size, SEEK_SET) != 0)
+		ret = -error_set_code(1, "%s", strerror(errno));
+	return ret;
+}
+
+
 /* arch_exit */
 int arch_exit(Arch * arch)
 {
@@ -519,7 +537,7 @@ int arch_init(Arch * arch, char const * filename, FILE * fp)
 	arch->helper.get_instruction_by_opcode = arch_get_instruction_by_opcode;
 	arch->helper.get_register_by_id_size = arch_get_register_by_id_size;
 	arch->helper.get_register_by_name_size = arch_get_register_by_name_size;
-	arch->helper.read = NULL;
+	arch->helper.read = _arch_read;
 	arch->helper.write = _arch_write;
 	arch->plugin->helper = &arch->helper;
 	return 0;
@@ -568,6 +586,21 @@ static char const * _arch_get_filename(Arch * arch)
 }
 
 
+/* arch_read */
+static ssize_t _arch_read(Arch * arch, void * buf, size_t size)
+{
+	if(fread(buf, size, 1, arch->fp) == 1)
+		return size;
+	if(ferror(arch->fp))
+		return -error_set_code(1, "%s: %s", arch->filename,
+				strerror(errno));
+	if(feof(arch->fp))
+		return -error_set_code(1, "%s: %s", arch->filename,
+				"End of file reached");
+	return -error_set_code(1, "%s: %s", arch->filename, "Read error");
+}
+
+
 /* arch_read_buffer */
 static ssize_t _arch_read_buffer(Arch * arch, void * buf, size_t size)
 {
diff --git a/src/arch.h b/src/arch.h
index a29be9b..258128c 100644
--- a/src/arch.h
+++ b/src/arch.h
@@ -60,5 +60,6 @@ int arch_write(Arch * arch, ArchInstruction * instruction,
 
 /* disassembly */
 int arch_decode(Arch * arch);
+int arch_decode_at(Arch * arch, off_t offset, size_t size, off_t base);
 
 #endif /* !ASM_ARCH_H */
diff --git a/src/asm.c b/src/asm.c
index d906cde..2bde581 100644
--- a/src/asm.c
+++ b/src/asm.c
@@ -154,6 +154,21 @@ int as_decode(As * as, char const * buffer, size_t size)
 }
 
 
+/* as_decode_file */
+int as_decode_file(As * as, char const * filename, FILE * fp)
+{
+	int ret;
+
+	if(fp != NULL)
+		return code_decode_file(as->code, filename, fp);
+	if((fp = fopen(filename, "r")) == NULL)
+		return -error_set_code(1, "%s: %s", filename, strerror(errno));
+	ret = code_decode_file(as->code, filename, fp);
+	fclose(fp);
+	return ret;
+}
+
+
 /* as_parse */
 int as_parse(As * as, char const * infile, char const * outfile)
 {
diff --git a/src/code.c b/src/code.c
index e0eb1ea..c07a743 100644
--- a/src/code.c
+++ b/src/code.c
@@ -137,6 +137,35 @@ int code_decode(Code * code, char const * buffer, size_t size)
 	arch_exit(code->arch);
 	return ret;
 }
+
+
+/* code_decode_file */
+static int _decode_file_callback(void * priv, char const * section,
+		off_t offset, size_t size, off_t base);
+
+int code_decode_file(Code * code, char const * filename, FILE * fp)
+{
+	int ret;
+
+	arch_init(code->arch, filename, fp);
+	format_init(code->format, filename, fp);
+	ret = format_decode(code->format, _decode_file_callback, code);
+	format_exit(code->format);
+	arch_exit(code->arch);
+	return ret;
+}
+
+static int _decode_file_callback(void * priv, char const * section,
+		off_t offset, size_t size, off_t base)
+{
+	Code * code = priv;
+
+	if(section != NULL)
+		printf("%s%s:\n", "\nDisassembly of section ", section);
+	return arch_decode_at(code->arch, offset, size, base);
+}
+
+
 #if 0
 static ArchInstruction * _decode_size(Code * code, size_t * size,
 		ArchInstruction * ai);
diff --git a/src/code.h b/src/code.h
index ead452d..0fe61e7 100644
--- a/src/code.h
+++ b/src/code.h
@@ -50,5 +50,6 @@ int code_section(Code * code, char const * section);
 
 /* disassembly */
 int code_decode(Code * code, char const * buffer, size_t size);
+int code_decode_file(Code * code, char const * filename, FILE * fp);
 
 #endif /* !ASM_CODE_H */
diff --git a/src/deasm.c b/src/deasm.c
index 8c29a22..acc3d98 100644
--- a/src/deasm.c
+++ b/src/deasm.c
@@ -53,7 +53,6 @@ typedef struct _DeasmFormat
 typedef struct _Deasm
 {
 	char const * arch;
-	As * as;
 
 	FormatPluginHelper helper;
 	DeasmFormat * format;
@@ -108,7 +107,6 @@ static int _deasm(char const * arch, char const * format,
 	Deasm deasm;
 
 	deasm.arch = arch;
-	deasm.as = NULL;
 	deasm.helper.format = &deasm;
 	deasm.helper.read = _deasm_helper_read;
 	deasm.helper.seek = _deasm_helper_seek;
@@ -123,8 +121,6 @@ static int _deasm(char const * arch, char const * format,
 		ret = _deasm_do_format(&deasm, format);
 	else
 		ret = _deasm_do(&deasm);
-	if(deasm.as != NULL)
-		as_delete(deasm.as);
 	fclose(deasm.fp);
 	_deasm_format_close_all(&deasm);
 	if(ret != 0)
@@ -205,6 +201,7 @@ static int _deasm_do(Deasm * deasm)
 static int _deasm_do_callback(Deasm * deasm, FormatPlugin * format)
 {
 	int ret;
+	As * as;
 
 #ifdef DEBUG
 	fprintf(stderr, "DEBUG: %s(\"%s\")\n", __func__, format->name);
@@ -217,11 +214,12 @@ static int _deasm_do_callback(Deasm * deasm, FormatPlugin * format)
 		if((deasm->arch = format->detect(format)) == NULL)
 			return -1;
 	}
-	if((deasm->as = as_new(deasm->arch, format->name)) == NULL)
+	if((as = as_new(deasm->arch, format->name)) == NULL)
 		return -error_print("deasm");
-	printf("\n%s: %s-%s\n", deasm->filename, format->name,
-			as_get_arch_name(deasm->as));
-	ret = format->decode(format);
+	printf("\n%s: %s-%s\n", deasm->filename, format->name, as_get_arch_name(
+				as));
+	ret = as_decode_file(as, deasm->filename, deasm->fp);
+	as_delete(as);
 	return ret;
 }
 
diff --git a/src/format.c b/src/format.c
index 6f9485b..1354b64 100644
--- a/src/format.c
+++ b/src/format.c
@@ -39,6 +39,11 @@ struct _Format
 	/* file */
 	char const * filename;
 	FILE * fp;
+
+	/* diassembly */
+	int (*decode_callback)(void * priv, char const * section, off_t offset,
+			size_t size, off_t base);
+	void * decode_priv;
 };
 
 
@@ -105,6 +110,37 @@ char const * format_get_name(Format * format)
 
 
 /* useful */
+/* format_decode */
+static int _decode_callback(Format * format, char const * section,
+		off_t offset, size_t size, off_t base);
+
+int format_decode(Format * format, int (*callback)(void * priv,
+			char const * section, off_t offset, size_t size,
+			off_t base), void * priv)
+{
+	int ret;
+
+	if(format->plugin->decode == NULL)
+		return error_set_code(1, "%s: %s", format_get_name(format),
+				"Disassembly is not supported");
+	format->helper.decode = _decode_callback;
+	format->decode_callback = callback;
+	format->decode_priv = priv;
+	ret = format->plugin->decode(format->plugin);
+	format->decode_callback = NULL;
+	format->decode_priv = NULL;
+	format->helper.decode = NULL;
+	return ret;
+}
+
+static int _decode_callback(Format * format, char const * section,
+		off_t offset, size_t size, off_t base)
+{
+	return format->decode_callback(format->decode_priv, section, offset,
+			size, base);
+}
+
+
 /* format_exit */
 int format_exit(Format * format)
 {
@@ -116,6 +152,7 @@ int format_exit(Format * format)
 	if(format->plugin->exit != NULL)
 		ret = format->plugin->exit(format->plugin);
 	format->helper.format = NULL;
+	format->helper.decode = NULL;
 	format->helper.read = NULL;
 	format->helper.seek = NULL;
 	format->plugin->helper = NULL;
@@ -144,6 +181,7 @@ int format_init(Format * format, char const * filename, FILE * fp)
 	format->filename = filename;
 	format->fp = fp;
 	format->helper.format = format;
+	format->helper.decode = NULL;
 	format->helper.get_filename = _format_get_filename;
 	format->helper.read = _format_read;
 	format->helper.seek = _format_seek;
diff --git a/src/format.h b/src/format.h
index 307bc7d..528df34 100644
--- a/src/format.h
+++ b/src/format.h
@@ -38,4 +38,9 @@ int format_exit(Format * format);
 int format_function(Format * format, char const * function);
 int format_section(Format * format, char const * section);
 
+/* disassembly */
+int format_decode(Format * format, int (*callback)(void * priv,
+			char const * section, off_t offset, size_t size,
+			off_t base), void * priv);
+
 #endif /* !ASM_FORMAT_H */