From 802a113dc94f71b6d757fec2951258a94b557387 Mon Sep 17 00:00:00 2001 From: Nick Clifton Date: Mon, 28 Feb 2005 18:05:06 +0000 Subject: Update documentation about ARC's extension instructions. --- gas/doc/c-arc.texi | 148 +++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 137 insertions(+), 11 deletions(-) (limited to 'gas/doc') diff --git a/gas/doc/c-arc.texi b/gas/doc/c-arc.texi index 700a01d..f03fa9c 100644 --- a/gas/doc/c-arc.texi +++ b/gas/doc/c-arc.texi @@ -1,4 +1,4 @@ -@c Copyright 2000, 2001 Free Software Foundation, Inc. +@c Copyright 2000, 2001, 2005 Free Software Foundation, Inc. @c This is part of the GAS manual. @c For copying conditions, see the file as.texinfo. @@ -34,7 +34,7 @@ @cindex @code{-marc[5|6|7|8]} command line option, ARC @item -marc[5|6|7|8] -This option selects the core processor variant. Using +This option selects the core processor variant. Using @code{-marc} is the same as @code{-marc@value{ARC_CORE_DEFAULT}}, which is also the default. @@ -46,10 +46,10 @@ Base instruction set. @cindex @code{arc6} arc6, ARC @item arc6 -Jump-and-link (jl) instruction. No requirement of an instruction between -setting flags and conditional jump. For example: +Jump-and-link (jl) instruction. No requirement of an instruction between +setting flags and conditional jump. For example: -@smallexample +@smallexample @ta mov.f r0,r1 beq foo @end smallexample @@ -137,36 +137,161 @@ machine directives: @cindex @code{extAuxRegister} directive, ARC @item .extAuxRegister @var{name},@var{address},@var{mode} -*TODO* +The ARCtangent A4 has extensible auxiliary register space. The +auxiliary registers can be defined in the assembler source code by +using this directive. The first parameter is the @var{name} of the +new auxiallry register. The second parameter is the @var{address} of +the register in the auxiliary register memory map for the variant of +the ARC. The third parameter specifies the @var{mode} in which the +register can be operated is and it can be one of: + +@table @code +@item r (readonly) +@item w (write only) +@item r|w (read or write) +@end table + +For example: @smallexample .extAuxRegister mulhi,0x12,w @end smallexample +This specifies an extension auxiliary register called @emph{mulhi} +which is at address 0x12 in the memory space and which is only +writable. + @cindex @code{extCondCode} directive, ARC @item .extCondCode @var{suffix},@var{value} -*TODO* +The condition codes on the ARCtangent A4 are extensible and can be +specified by means of this assembler directive. They are specified +by the suffix and the value for the condition code. They can be used to +specify extra condition codes with any values. For example: @smallexample .extCondCode is_busy,0x14 + + add.is_busy r1,r2,r3 + bis_busy _main @end smallexample @cindex @code{extCoreRegister} directive, ARC @item .extCoreRegister @var{name},@var{regnum},@var{mode},@var{shortcut} -*TODO* +Specifies an extension core register @var{name} for the application. +This allows a register @var{name} with a valid @var{regnum} between 0 +and 60, with the following as valid values for @var{mode} + +@table @samp +@item @emph{r} (readonly) +@item @emph{w} (write only) +@item @emph{r|w} (read or write) +@end table + + +The other parameter gives a description of the register having a +@var{shortcut} in the pipeline. The valid values are: + +@table @code +@item can_shortcut +@item cannot_shortcut +@end table + +For example: @smallexample .extCoreRegister mlo,57,r,can_shortcut @end smallexample +This defines an extension core register mlo with the value 57 which +can shortcut the pipeline. + @cindex @code{extInstruction} directive, ARC @item .extInstruction @var{name},@var{opcode},@var{subopcode},@var{suffixclass},@var{syntaxclass} -*TODO* +The ARCtangent A4 allows the user to specify extension instructions. +The extension instructions are not macros. The assembler creates +encodings for use of these instructions according to the specification +by the user. The parameters are: + +@table @bullet +@item @var{name} +Name of the extension instruction + +@item @var{opcode} +Opcode to be used. (Bits 27:31 in the encoding). Valid values +0x10-0x1f or 0x03 + +@item @var{subopcode} +Subopcode to be used. Valid values are from 0x09-0x3f. However the +correct value also depends on @var{syntaxclass} + +@item @var{suffixclass} +Determines the kinds of suffixes to be allowed. Valid values are +@code{SUFFIX_NONE}, @code{SUFFIX_COND}, +@code{SUFFIX_FLAG} which indicates the absence or presence of +conditional suffixes and flag setting by the extension instruction. +It is also possible to specify that an instruction sets the flags and +is conditional by using @code{SUFFIX_CODE} | @code{SUFFIX_FLAG}. + +@item @var{syntaxclass} +Determines the syntax class for the instruction. It can have the +following values: + +@table @code +@item{SYNTAX_2OP}: +2 Operand Instruction +@item{SYNTAX_3OP}: +3 Operand Instruction +@end table + +In addition there could be modifiers for the syntax class as described +below: + +@itemize @minus +Syntax Class Modifiers are: + +@item @code{OP1_MUST_BE_IMM}: +Modifies syntax class SYNTAX_3OP, specifying that the first operand +of a three-operand instruction must be an immediate (i.e. the result +is discarded). OP1_MUST_BE_IMM is used by bitwise ORing it with +SYNTAX_3OP as given in the example below. This could usually be used +to set the flags using specific instructions and not retain results. + +@item @code{OP1_IMM_IMPLIED}: +Modifies syntax class SYNTAX_20P, it specifies that there is an +implied immediate destination operand which does not appear in the +syntax. For example, if the source code contains an instruction like: @smallexample - .extInstruction mul64,0x14,0x0,SUFFIX_COND,SYNTAX_3OP|OP1_MUST_BE_IMM +inst r1,r2 @end smallexample +it really means that the first argument is an implied immediate (that +is, the result is discarded). This is the same as though the source +code were: inst 0,r1,r2. You use OP1_IMM_IMPLIED by bitwise ORing it +with SYNTAX_20P. + +@end itemize +@end table + +For example, defining 64-bit multiplier with immediate operands: + +@smallexample +.extInstruction mp64,0x14,0x0,SUFFIX_COND | SUFFIX_FLAG , + SYNTAX_3OP|OP1_MUST_BE_IMM +@end smallexample + +The above specifies an extension instruction called mp64 which has 3 operands, +sets the flags, can be used with a condition code, for which the +first operand is an immediate. (Equivalent to discarding the result +of the operation). + +@smallexample + .extInstruction mul64,0x14,0x00,SUFFIX_COND, SYNTAX_2OP|OP1_IMM_IMPLIED +@end smallexample + +This describes a 2 operand instruction with an implicit first +immediate operand. The result of this operation would be discarded. + @cindex @code{half} directive, ARC @item .half @var{expressions} *TODO* @@ -204,4 +329,5 @@ between the two - even for the implicit default core version @cindex opcodes for ARC For information on the ARC instruction set, see @cite{ARC Programmers -Reference Manual}, ARC Cores Ltd. +Reference Manual}, ARC International (www.arc.com) + -- cgit v1.1