.align pseudo-op

Purpose

Advances the current location counter until a boundary specified by the Number parameter is reached.

Syntax

.align Number [, Number2]

Description

The .align pseudo-op is normally used in a control section (csect) that contains data or in a csect that contains prefixed instructions.

The Number parameter specifies the log base 2 (binary logarithm) for the required alignment of the location counter. For example, if you specify 2, the .align pseudo-op requests word alignment, and if you specify 3, the .align pseudo-op requests double word alignment.

If the Number2 parameter is specified, alignment occurs only if the location is within Number2 bytes of the required alignment boundary. This is most useful before a prefixed instruction to prevent the instruction from crossing a 64-byte boundary.

If the Number2 parameter is not specified, the assembler aligns the location counter by inserting bytes. In most cases, 0s are inserted, but if the current csect has a storage-mapping class of PR or GL, no-op instructions are inserted. For more information about storage-mapping classes, see the .csect pseudo-op.

Parameters

Item	Description
Number	Specifies an absolute expression that evaluates to an integer value from 0 to 12, inclusive. The value indicates the log base 2 of the desired alignment. For example, an alignment of 8 (a double word) would be represented by an integer value of 3; an alignment of 4096 (one page) would be represented by an integer value of 12.
Number2	Specifies an absolute expression that evaluates to a number. Alignment occurs only if the location counter is closer to the desired alignment boundary than Number2 bytes. If the value specified by the Number2 parameter is greater than 2^Number, the Number2 parameter is ignored.

Examples

The following examples demonstrate the use of the .align pseudo-op:


                .csect   progdata[RW]
                .byte    1
                         # Location counter now at odd number
                .align   1
                         # Location counter is now at the next
                         # halfword boundary.
                .byte    3,4
                .
                .
                .
                .align   2       # Insure that the label cont
                                 # and the .long pseudo-op are
                                 # aligned on a full word
                                 # boundary.
        cont:   .long    5004381


                .csect [PR]
                …
                .align 6,8	# Align the program counter if the 
                                 # current location counter is less 
                                 # than 8 bytes from a 64-bit byte  
                                 # boundary
                plw r3,0x10000(r4)	# Load a word into r3