Chapter 8. Assembler Directives

57

The third expression is also absolute, and is also optional. If it is present, it is the maximum number of

bytes that should be skipped by this alignment directive. If doing the alignment would require skipping

more bytes than the specified maximum, then the alignment is not done at all. You can omit the fill

value (the second argument) entirely by simply using two commas after the required alignment; this

can be useful if you want the alignment to be filled with no op instructions when appropriate.

The

.p2alignw

and

.p2alignl

directives are variants of the

.p2align

directive. The

.p2alignw

directive treats the fill pattern as a two byte word value. The

.p2alignl

directives treats the fill

pattern as a four byte longword value. For example,

.p2alignw 2,0x368d

will align to a multiple

of 4. If it skips two bytes, they will be filled in with the value 0x368d (the exact placement of the bytes

depends upon the endianness of the processor). If it skips 1 or 3 bytes, the fill value is undefined.

8.67.

.previous

This is one of the ELF section stack manipulation directives. The others are

.section

(Section 8.78

.section name

),

.subsection

(Section 8.89

.subsection name

),

.pushsection

(Section 8.73

.pushsection name, subsection

), and

.popsection

(Section 8.68

.popsection

).

This directive swaps the current section (and subsection) with most recently referenced section (and

subsection) prior to this one. Multiple

.previous

directives in a row will flip between two sections

(and their subsections).

In terms of the section stack, this directive swaps the current section with the top section on the section

stack.

8.68.

.popsection

This is one of the ELF section stack manipulation directives. The others are

.section

(Section 8.78

.section name

),

.subsection

(Section 8.89

.subsection name

),

.pushsection

(Section 8.73

.pushsection name, subsection

), and

.previous

(Section 8.67

.previous

).

This directive replaces the current section (and subsection) with the top section (and subsection) on

the section stack. This section is popped off the stack.

8.69.

.print string

as

will print

string

on the standard output during assembly. You must put

string

in double quotes.

8.70.

.protected names

This is one of the ELF visibility directives. The other two are

.hidden

(Section 8.42

.hidden

names

) and

.internal

(Section 8.49

.internal names

).

This directive overrides the named symbols default visibility (which is set by their binding: local,

global or weak). The directive sets the visibility to

protected

which means that any references to

the symbols from within the components that defines them must be resolved to the definition in that

component, even if a definition in another component would normally preempt this.

8.71.

.psize lines, columns

Use this directive to declare the number of lines  and, optionally, the number of columns  to use for

each page, when generating listings.