Chapter 4. Syntax

27

A label is a symbol immediately followed by a colon (

:

). Whitespace before a label or after a colon

is permitted, but you may not have whitespace between a label's symbol and its colon. Section 6.1

Labels.

For HPPA targets, labels need not be immediately followed by a colon, but the definition of a label

must begin in column zero. This also implies that only one label may be defined on each line.

label:

.directive

followed by something

another_label:

# This is an empty statement.

instruction

operand_1, operand_2, ...

4.6. Constants

A constant is a number, written so that its value is known by inspection, without knowing any context.

Like this:

.byte

74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.

.ascii "Ring the bell\7"

# A string constant.

.octa

0x123456789abcdef0123456789ABCDEF0 # A bignum.

.float 0f 314159265358979323846264338327\

95028841971.693993751E 40

#   pi, a flonum.

4.6.1. Character Constants

There are two kinds of character constants. A character stands for one character in one byte and

its value may be used in numeric expressions. String constants (properly called string literals) are

potentially many bytes and their values may not be used in arithmetic expressions.

4.6.1.1. Strings

A string is written between double quotes. It may contain double quotes or null characters. The way

to get special characters into a string is to escape these characters: precede them with a backslash

\

character. For example

\\

represents one backslash: the first

\

is an escape which tells

as

to interpret

the second character literally as a backslash (which prevents

as

from recognizing the second

\

as an

escape character). The complete list of escapes follows.

\b

Mnemonic for backspace; for ASCII this is octal code 010.

\f

Mnemonic for FormFeed; for ASCII this is octal code 014.

\n

Mnemonic for newline; for ASCII this is octal code 012.