Microchip Technology XC8 Standard Compiler (Workstation) SW006021-1 SW006021-1 User Manual
Product codes
SW006021-1
MPLAB
®
XC8 C Compiler User’s Guide
DS52053B-page 254
2012 Microchip Technology Inc.
6.4.8
Program Sections
Program sections, or psects, are simply a section of code or data. They are a way of
grouping together parts of a program (via the psect’s name) even though the source
code may not be physically adjacent in the source file, or even where spread over
several modules. For an introductory guide to psects, see Section 5.15.1 “Program
Sections”.
grouping together parts of a program (via the psect’s name) even though the source
code may not be physically adjacent in the source file, or even where spread over
several modules. For an introductory guide to psects, see Section 5.15.1 “Program
Sections”.
A psect is identified by a name and has several attributes. The PSECT assembler direc-
tive is used to define a psect. It takes as arguments a name and an optional
comma-separated list of flags. See Section 5.15.2 “Compiler-Generated Psects” for
a list of all psects that the code generator defines. Chapter 7. “Linker” has more infor-
mation on the operation of the linker and on options that can be used to control psect
placement in memory.
tive is used to define a psect. It takes as arguments a name and an optional
comma-separated list of flags. See Section 5.15.2 “Compiler-Generated Psects” for
a list of all psects that the code generator defines. Chapter 7. “Linker” has more infor-
mation on the operation of the linker and on options that can be used to control psect
placement in memory.
The assembler associates no significance to the name of a psect and the linker is also
not aware of which psects are compiler-generated or which are user-defined. Unless
defined as abs (absolute), psects are relocatable.
not aware of which psects are compiler-generated or which are user-defined. Unless
defined as abs (absolute), psects are relocatable.
Code or data that is not explicitly placed into a psect will become part of the default
(unnamed) psect.
(unnamed) psect.
6.4.9
Assembler Directives
Assembler directives, or pseudo-ops, are used in a similar way to instruction mnemon-
ics. With the exception of PAGESEL and BANKSEL, these directives do not generate
instructions. The DB, DW and DDW directives place data bytes into the current psect. The
directives are listed in Table 6-5, and are detailed below in the following sections.
ics. With the exception of PAGESEL and BANKSEL, these directives do not generate
instructions. The DB, DW and DDW directives place data bytes into the current psect. The
directives are listed in Table 6-5, and are detailed below in the following sections.
TABLE 6-5:
ASPIC[18] ASSEMBLER DIRECTIVES
Directive
Purpose
GLOBAL
Make symbols accessible to other modules or allow reference to other
modules’ symbols
modules’ symbols
END
End assembly
PSECT
Declare or resume program section
ORG
Set location counter within current psect
EQU
Define symbol value
SET
Define or re-define symbol value
DB
Define constant byte(s)
DW
Define constant word(s)
DDW
Define double-width constant word(s) (PIC18 devices only)
DS
Reserve storage
DABS
Define absolute storage
IF
Conditional assembly
ELSIF
Alternate conditional assembly
ELSE
Alternate conditional assembly
ENDIF
End conditional assembly
FNCALL
Inform the linker that one function calls another
FNROOT
Inform the linker that a function is the “root” of a call graph
MACRO
Macro definition
ENDM
End macro definition
LOCAL
Define local tabs
ALIGN
Align output to the specified boundary
BANKSEL
Generate code to select bank of operand