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Chapter 40. VAX Dependent Features

The

 h n

option determines how we map names. This takes several values. No

 h

switch at all

allows case hacking as described above. A value of zero (

 h0

) implies names should be upper

case, and inhibits the case hack. A value of 2 (

 h2

) implies names should be all lower case, with

no case hack. A value of 3 (

 h3

) implies that case should be preserved. The value 1 is unused.

The

 H

option directs

as

to display every mapped symbol during assembly.

Symbols whose names include a dollar sign

$

are exceptions to the general name mapping. These

symbols are normally only used to reference VMS library names. Such symbols are always

mapped to upper case.

 +

The

 +

option causes

as

to truncate any symbol name larger than 31 characters. The

 +

option

also prevents some code following the

_main

symbol normally added to make the object file

compatible with Vax 11 "C".

 1

This option is ignored for backward compatibility with

as

version 1.x.

 H

The

 H

option causes

as

to print every symbol which was changed by case mapping.

40.2. VAX Floating Point

Conversion of flonums to floating point is correct, and compatible with previous assemblers. Rounding

is towards zero if the remainder is exactly half the least significant bit.

D

,

F

,

G

and

H

floating point formats are understood.

Immediate floating literals (e.g.

S`$6.9

) are rendered correctly. Again, rounding is towards zero in

the boundary case.

The

.float

directive produces

f

format numbers. The

.double

directive produces

d

format num 

bers.

40.3. Vax Machine Directives

The Vax version of the assembler supports four directives for generating Vax floating point constants.

They are described in the table below.

.dfloat

This expects zero or more flonums, separated by commas, and assembles Vax

d

format 64 bit

floating point constants.

.ffloat

This expects zero or more flonums, separated by commas, and assembles Vax

f

format 32 bit

floating point constants.