Zilog ZUSBOPTS - Manual (Page 241)

UM017105-0511 Address Spaces and Segments
Zilog Developer Studio II – ZNEO™
User Manual
213
Segments
Segments are used to represent regions of memory. Only one segment is considered active
at any time during the assembly process. A segment must be defined before setting it as
the current segment. Every segment is associated with one and only one address space.
Predefined Segments
For convenience, the segments listed in Table 19 are predefined by the assembler.
User-Defined Segments
You can define a new segment using the following directives:
DEFINE MYSEG,SPACE=ROM
SEGMENT MYSEG
MYSEG becomes the current segment when the assembler processes the SEGMENT direc-
tive, and MYSEG remains the current segment until a new SEGMENT directive appears.
MYSEG can be used as a segment name in the linker command file.
You can define a new segment in ERAM space using the following directives:
DEFINE MYDATA,SPACE=ERAM
SEGMENT MYDATA
The DEFINE directive creates a new segment and attaches it to a space. For more informa-
tion about using the DEFINE directive, see the DEFINE section on page 231. The SEG -
Table 19. Predefined Segments
Segment ID Space Alignment Type Contents
CODE EROM 2 bytes Relocatable Code
EROM_DATA EROM 1 byte Relocatable Constant data, tables, and strings
EROM_TEXT EROM 1 byte Relocatable Constant strings
ROM_DATA ROM 1 byte Relocatable Constant data, tables, and strings
ROM_TEXT ROM 1 byte Relocatable Constant strings
__VECTORS ROM 1 byte Absolute Interrupt vector table
NEAR_DATA RAM 1 byte Relocatable Initialized near data
NEAR_BSS RAM 1 byte Relocatable Uninitialized near data
NEAR_TEXT RAM 1 byte Relocatable Near strings
FAR_DATA RAM 1 byte Relocatable Initialized far data
FAR_BSS RAM 1 byte Relocatable Uninitialized far data
FAR_TEXT RAM 1 byte Relocatable Far strings
IOSEG IODATA 1 byte Relocatable I/O data