Development Tools

A.1.1 Changing Mapped Areas

The defaults for the mapped sections of variables are as follows:

-	Variables without initial values: Sections B, B_2, and B_1

-	Variables with initial values: Sections D, D_2, and D_1 (ROM) and sections R, R_2, and R_1 (RAM)

-	const variables: Sections C, C_2, and C_1

For changing the area (section) to map variables, specify the section type and section name through #pragma section.

#pragma section <section type> <section name>

Variable declaration/definition

#pragma section

When a section type is specified, only section names of the specified type can be changed.

Note that in the RX family C/C++ compiler, the section to map a variable depends on the alignment value of the variable.

Example

B: Variables without initial values and an alignment value of four bytes are mapped

B_2: Variables without initial values and an alignment value of two bytes are mapped

B_1: Variables without initial values and an alignment value of one byte are mapped

For variables with initial values, the initial value is mapped to ROM and the variable itself is mapped to RAM (both ROM and RAM areas are necessary). When the resetprg.c file of the startup routine is used, the INITSCT function copies the initial values in ROM to the variables in RAM.

The relationship between the section type and the created section is shown in the following.

Name	Section Name	Attribute	Format Type	Initial Value and Write Operation	Alignment Value
Constant area	C12	romdata	Relative	Has initial values and writing is not possible	4 bytes
	C_212	romdata	Relative	Has initial values and writing is not possible	2 bytes
	C_112	romdata	Relative	Has initial values and writing is not possible	1 byte
Initialized data area	D12	romdata	Relative	Has initial values and writing is possible	4 bytes
	D_212	romdata	Relative	Has initial values and writing is possible	2 bytes
	D_112	romdata	Relative	Has initial values and writing is possible	1 byte
Uninitialized data area	B12	data	Relative	Does not have initial values and writing is possible	4 bytes
	B_212	data	Relative	Does not have initial values and writing is possible	2 bytes
	B_112	data	Relative	Does not have initial values and writing is possible	1 byte
switch statement branch table area	W12	romdata	Relative	Has initial values and writing is not possible	4 bytes
	W_212	romdata	Relative	Has initial values and writing is not possible	2 bytes
	W_112	romdata	Relative	Has initial values and writing is not possible	1 byte
C++ initial processing/ postprocessing data area	C$INT	romdata	Relative	Has initial values and writing is not possible	4 bytes
C++ virtual function table area	C$VTBL	romdata	Relative	Has initial values and writing is not possible	4 bytes
Absolute address variable area	$ADDR_ <section>_ <address>*3	data	Absolute	Has or does not have initial values and writing is possible or not possible*4	
Variable vector area	C$VECT	romdata	Relative	Does not have initial values and writing is possible	

Example 1.

Section names can be switched by the section option or the #pragma section extension. However, partial data (e.g., string literal) is not affected by #pragma section. For details, see the detailed description of 4.2.3 #pragma Directive - #pragma section.

Example 2.

Specifying a section with an alignment value of 4 when switching the section names also changes the section name of sections with an alignment value of 1 or 2. When #pragma endian is used to specify an endian that differs from the setting by the endian option, a dedicated section is created and the relevant data stored. For this section, after the section name, _B is added for #pragma endian big and _L is added for #pragma endian little. However, partial data (e.g., string literal) is not affected by #pragma endian. For details, see the detailed description of 4.2.3 #pragma Directive - #pragma endian.

Example 3.

<section> is a C, D, or B section name, and <address> is an absolute address (hexadecimal).

Example 4.

The initial value and write operation depend on the attribute of <section>.