92 lines
3 KiB
Text
92 lines
3 KiB
Text
@c Copyright 2007, 2008 Free Software Foundation, Inc.
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@c This is part of the GAS manual.
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@c For copying conditions, see the file as.texinfo.
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@ifset GENERIC
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@page
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@node CR16-Dependent
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@chapter CR16 Dependent Features
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@end ifset
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@ifclear GENERIC
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@node Machine Dependencies
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@chapter CR16 Dependent Features
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@end ifclear
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@cindex CR16 support
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@menu
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* CR16 Operand Qualifiers:: CR16 Machine Operand Qualifiers
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@end menu
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@node CR16 Operand Qualifiers
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@section CR16 Operand Qualifiers
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@cindex CR16 Operand Qualifiers
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The National Semiconductor CR16 target of @code{@value{AS}} has a few machine dependent operand qualifiers.
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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:
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@table @code
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@item s
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- @code{Specifies expression operand type as small}
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@item m
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- @code{Specifies expression operand type as medium}
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@item l
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- @code{Specifies expression operand type as large}
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@item c
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- @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.}
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@item got/GOT
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- @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}
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@item cgot/cGOT
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- @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.}
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@end table
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CR16 target operand qualifiers and its size (in bits):
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@table @samp
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@item Immediate Operand
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- s ---- 4 bits
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@item
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- m ---- 16 bits, for movb and movw instructions.
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@item
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- m ---- 20 bits, movd instructions.
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@item
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- l ---- 32 bits
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@item Absolute Operand
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- s ---- Illegal specifier for this operand.
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@item
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- m ---- 20 bits, movd instructions.
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@item Displacement Operand
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- s ---- 8 bits
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@item
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- m ---- 16 bits
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@item
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- l ---- 24 bits
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@end table
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For example:
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@example
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1 @code{movw $_myfun@@c,r1}
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This loads the address of _myfun, shifted right by 1, into r1.
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2 @code{movd $_myfun@@c,(r2,r1)}
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This loads the address of _myfun, shifted right by 1, into register-pair r2-r1.
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3 @code{_myfun_ptr:}
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@code{.long _myfun@@c}
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@code{loadd _myfun_ptr, (r1,r0)}
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@code{jal (r1,r0)}
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This .long directive, the address of _myfunc, shifted right by 1 at link time.
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4 @code{loadd _data1@@GOT(r12), (r1,r0)}
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This loads the address of _data1, into global offset table (ie GOT) and its offset value from GOT loads into register-pair r2-r1.
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5 @code{loadd _myfunc@@cGOT(r12), (r1,r0)}
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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.
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@end example
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