Chapter 27. M68HC11 and M68HC12 Dependent Features

163

.relax

The relax directive is used by the

GNU Compiler

to emit a specific relocation to mark a group of

instructions for linker relaxation. The sequence of instructions within the group must be known

to the linker so that relaxation can be performed.

.mode [mshort|mlong|mshort double|mlong double]

This directive specifies the ABI. It overrides the

 mshort

,

 mlong

,

 mshort double

and

 mlong double

options.

.far symbol

This directive marks the symbol as a

far

symbol meaning that it uses a

call/rtc

calling con 

vention as opposed to

jsr/rts

. During a final link, the linker will identify references to the

far

symbol and will verify the proper calling convention.

.interrupt symbol

This directive marks the symbol as an interrupt entry point. This information is then used by the

debugger to correctly unwind the frame across interrupts.

.xrefb symbol

This directive is defined for compatibility with the

Specification for Motorola 8 and

16 Bit Assembly Language Input Standard

and is ignored.

27.5. Floating Point

Packed decimal (P) format floating literals are not supported. Feel free to add the code!

The floating point formats generated by directives are these.

.float

Single

precision floating point constants.

.double

Double

precision floating point constants.

.extend

.ldouble

Extended

precision (

long double

) floating point constants.

27.6. Opcodes

27.6.1. Branch Improvement

Certain pseudo opcodes are permitted for branch instructions. They expand to the shortest branch

instruction that reach the target. Generally these mnemonics are made by prepending

j

to the

start of Motorola mnemonic. These pseudo opcodes are not affected by the

 short branchs

or

 force long branchs

options.

The following table summarizes the pseudo operations.