Chapter 40.

VAX Dependent Features

40.1. VAX Command Line Options

The Vax version of

as

accepts any of the following options, gives a warning message that the option

was ignored and proceeds. These options are for compatibility with scripts designed for other people's

assemblers.

 D (Debug)

 S (Symbol Table)

 T (Token Trace)

These are obsolete options used to debug old assemblers.

 d (Displacement size for JUMPs)

This option expects a number following the

 d

. Like options that expect filenames, the number

may immediately follow the

 d

(old standard) or constitute the whole of the command line

argument that follows

 d

(gnu standard).

 V (Virtualize Interpass Temporary File)

Some other assemblers use a temporary file. This option commanded them to keep the informa 

tion in active memory rather than in a disk file.

as

always does this, so this option is redundant.

 J (JUMPify Longer Branches)

Many 32 bit computers permit a variety of branch instructions to do the same job. Some of these

instructions are short (and fast) but have a limited range; others are long (and slow) but can

branch anywhere in virtual memory. Often there are 3 flavors of branch: short, medium and long.

Some other assemblers would emit short and medium branches, unless told by this option to emit

short and long branches.

 t (Temporary File Directory)

Some other assemblers may use a temporary file, and this option takes a filename being the

directory to site the temporary file. Since

as

does not use a temporary disk file, this option

makes no difference.

 t

needs exactly one filename.

The Vax version of the assembler accepts additional options when compiled for VMS:

 h n

External symbol or section (used for global variables) names are not case sensitive on VAX/VMS

and always mapped to upper case. This is contrary to the C language definition which explicitly

distinguishes upper and lower case. To implement a standard conforming C compiler, names

must be changed (mapped) to preserve the case information. The default mapping is to convert

all lower case characters to uppercase and adding an underscore followed by a 6 digit hex value,

representing a 24 digit binary value. The one digits in the binary value represent which characters

are uppercase in the original symbol name.