mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-23 15:32:26 +00:00
125 lines
3.9 KiB
Plaintext
125 lines
3.9 KiB
Plaintext
@c Copyright (C) 2007-2017 Free Software Foundation, Inc.
|
|
@c This is part of the GAS manual.
|
|
@c For copying conditions, see the file as.texinfo.
|
|
|
|
@ifset GENERIC
|
|
@page
|
|
@node CR16-Dependent
|
|
@chapter CR16 Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter CR16 Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex CR16 support
|
|
@menu
|
|
* CR16 Operand Qualifiers:: CR16 Machine Operand Qualifiers
|
|
* CR16 Syntax:: Syntax for the CR16
|
|
@end menu
|
|
|
|
@node CR16 Operand Qualifiers
|
|
@section CR16 Operand Qualifiers
|
|
@cindex CR16 Operand Qualifiers
|
|
|
|
The National Semiconductor CR16 target of @code{@value{AS}} has a few machine dependent operand qualifiers.
|
|
|
|
Operand expression type qualifier is an optional field in the instruction operand, to determines the type of the expression field of an operand. The @code{@@} is required. CR16 architecture uses one of the following expression qualifiers:
|
|
|
|
@table @code
|
|
@item s
|
|
- @code{Specifies expression operand type as small}
|
|
@item m
|
|
- @code{Specifies expression operand type as medium}
|
|
@item l
|
|
- @code{Specifies expression operand type as large}
|
|
@item c
|
|
- @code{Specifies the CR16 Assembler generates a relocation entry for the operand, where pc has implied bit, the expression is adjusted accordingly. The linker uses the relocation entry to update the operand address at link time.}
|
|
@item got/GOT
|
|
- @code{Specifies the CR16 Assembler generates a relocation entry for the operand, offset from Global Offset Table. The linker uses this relocation entry to update the operand address at link time}
|
|
@item cgot/cGOT
|
|
- @code{Specifies the CompactRISC Assembler generates a relocation entry for the operand, where pc has implied bit, the expression is adjusted accordingly. The linker uses the relocation entry to update the operand address at link time.}
|
|
@end table
|
|
|
|
CR16 target operand qualifiers and its size (in bits):
|
|
|
|
@table @samp
|
|
@item Immediate Operand: s
|
|
4 bits.
|
|
|
|
@item Immediate Operand: m
|
|
16 bits, for movb and movw instructions.
|
|
|
|
@item Immediate Operand: m
|
|
20 bits, movd instructions.
|
|
|
|
@item Immediate Operand: l
|
|
32 bits.
|
|
|
|
@item Absolute Operand: s
|
|
Illegal specifier for this operand.
|
|
|
|
@item Absolute Operand: m
|
|
20 bits, movd instructions.
|
|
|
|
@item Displacement Operand: s
|
|
8 bits.
|
|
|
|
@item Displacement Operand: m
|
|
16 bits.
|
|
|
|
@item Displacement Operand: l
|
|
24 bits.
|
|
|
|
@end table
|
|
|
|
For example:
|
|
@example
|
|
1 @code{movw $_myfun@@c,r1}
|
|
|
|
This loads the address of _myfun, shifted right by 1, into r1.
|
|
|
|
2 @code{movd $_myfun@@c,(r2,r1)}
|
|
|
|
This loads the address of _myfun, shifted right by 1, into register-pair r2-r1.
|
|
|
|
3 @code{_myfun_ptr:}
|
|
@code{.long _myfun@@c}
|
|
@code{loadd _myfun_ptr, (r1,r0)}
|
|
@code{jal (r1,r0)}
|
|
|
|
This .long directive, the address of _myfunc, shifted right by 1 at link time.
|
|
|
|
4 @code{loadd _data1@@GOT(r12), (r1,r0)}
|
|
|
|
This loads the address of _data1, into global offset table (ie GOT) and its offset value from GOT loads into register-pair r2-r1.
|
|
|
|
5 @code{loadd _myfunc@@cGOT(r12), (r1,r0)}
|
|
|
|
This loads the address of _myfun, shifted right by 1, into global offset table (ie GOT) and its offset value from GOT loads into register-pair r1-r0.
|
|
@end example
|
|
|
|
@node CR16 Syntax
|
|
@section CR16 Syntax
|
|
@menu
|
|
* CR16-Chars:: Special Characters
|
|
@end menu
|
|
|
|
@node CR16-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, CR16
|
|
@cindex CR16 line comment character
|
|
The presence of a @samp{#} on a line indicates the start of a comment
|
|
that extends to the end of the current line. If the @samp{#} appears
|
|
as the first character of a line, the whole line is treated as a
|
|
comment, but in this case the line can also be a logical line number
|
|
directive (@pxref{Comments}) or a preprocessor control command
|
|
(@pxref{Preprocessing}).
|
|
|
|
@cindex line separator, CR16
|
|
@cindex statement separator, CR16
|
|
@cindex CR16 line separator
|
|
The @samp{;} character can be used to separate statements on the same
|
|
line.
|