CHAPTER 4: ASSEMBLER

4.7.7 Location Defining Pseudo-Instructions (.org, .align)

The absolute addressing pseudo-instructions (.align and .org) work to specify absolute location of a section in different precision such as 2n words alignment level and complete absolute address level.

.org pseudo-instruction

Instruction format

.org <Address>

<Address>:

Absolute address specification

•Only decimal, binary and hexadecimal numbers can be described.

•The addresses that can be specified are from 0 to 65,535 (0xffff).

•One or more spaces or tabs are necessary between the instruction and the address.

Sample description:

.code

.org 0x0100

Function

Specifies an absolute address location of a CODE, DATA or BSS section in an assembly source file. The section with the .org pseudo-instruction is taken as an absolute section.

Precautions

• If an overlap occurs as the result of specifying absolute locations with the .org pseudo-instruction, an

error will result.

 

 

Examples:

 

 

 

.bss

 

 

 

.org

0x00

 

 

.comm

RAM0

4

... RAM secured area (0x00–0x03)

.org

0x01

 

 

.comm

RAM1

4

... Error (because the area of 0x01–0x03 is overlapped)

• When the .org pseudo-instruction appears in a section, a new absolute section starts at that point. The section type does not change. The .org pseudo-instruction keeps its effect only in that section until the next section definer (.code, .data or .bss) or the next location definer (.org or .align) appears.

Example:

 

:

 

.code

... The latest relocatable section definition.

:

 

.org 0x100

... Starts new absolute CODE section from address 0x100.

:

 

.bss

... This section is relocatable not affected by the ".org" pseudo-instruction.

:

 

.code

... This section is also relocatable not affected by the ".org" pseudo-instruction.

:

 

•If the .org pseudo-instruction is defined immediately after a section definer (.code, .data or .bss), the section definer does not start a new section. But .org starts a new section with the attribute of the

section definer.

 

Example:

 

.code

... This does not start a new CODE section.

.org 0x100

... This starts an absolute CODE section.

:

 

74

EPSON

S5U1C63000A MANUAL

 

 

(S1C63 FAMILY ASSEMBLER PACKAGE)