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#
# This file is part of the program psim.
#
# Copyright (C) 1994-1995, Andrew Cagney <cagney@highland.com.au>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
# Instruction decode:
#
# The table that follows is used by gen to construct a decision tree
# that can identify each possible instruction. Gen then outputs this
# decision tree as (according to config) a table or switch statement
# as the function idecode.
#
# In parallel to this, as mentioned above, WITH_EXPANDED_SEMANTICS
# determines of the semantic functions themselves should be expanded
# in a similar way.
#
# The table contains the following entries:
#
# <valid>
#
# Must be 1 for the entry to be considered. The last entry must be
# zero.
#
# <first>
# <last>
#
# Range of bits (within the instruction) that should be searched for
# an instruction field. Within such ranges, gen looks for opcodes
# (constants), registers (strings) and reserved bits (slash) and
# according to the rules that follows includes or excludes them from
# a possible instruction field.
#
# <force_first>
# <force_last>
#
# If an instructioin field was found, enlarge the field size so that
# it is forced to at least include bits starting from <force_first>
# (<force_last>). To stop this occuring, use <force_first> = <last>
# + 1 and <force_last> = <first> - 1.
#
# <force_slash>
#
# Treat `/' fields as a constant instead of variable when looking for
# an instruction field.
#
# <force_expansion>
#
# Treat any contained register (string) fields as constant when
# determining the instruction field. For the instruction decode (and
# controled by IDECODE_EXPAND_SEMANTICS) this forces the expansion of
# what would otherwize be non constant bits of an instruction.
#
# <use_switch>
#
# Should this table be expanded using a switch statement (val 1) and
# if so, should it be padded with entries so as to force the compiler
# to generate a jump table (val 2).
#
# <special_mask>
# <special_value>
# <special_rule>
#
# Special rule to fine tune how specific (or groups) of instructions
# are expanded. The applicability of the rule is determined by
#
# <special_mask> != 0 && (instruction> & <special_mask>) == <special_value>
#
# Where <instruction> is obtained by looking only at constant fields
# with in an instructions spec. When determining an expansion, the
# rule is only considered when a node contains a single instruction.
# <special_rule> can be any of:
#
# 0: for this instruction, expand by earlier rules
# 1: expand bits <force_low> .. <force_hi> only
# 2: boolean expansion of only zero/non-zero cases
#
0: 5: 0: 5:0:: 1:0x00000000:0x00000000:0
21:31:32:-1:0:: 1:0x00000000:0x00000000:0
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