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Diffstat (limited to 'sim/igen/ld-decode.h')
| -rw-r--r-- | sim/igen/ld-decode.h | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/sim/igen/ld-decode.h b/sim/igen/ld-decode.h new file mode 100644 index 00000000000..b24a231266a --- /dev/null +++ b/sim/igen/ld-decode.h @@ -0,0 +1,235 @@ +/* This file is part of the program psim. + + Copyright (C) 1994,1995,1996, 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 table: + + <decode-rule> ::= + { <option> } + ":" [ <first> ] + ":" [ <last> ] + ":" [ <force-first> ] + ":" [ <force-last> ] + ":" [ <constant-field-names> ] + ":" [ <word-nr> ] + ":" [ <format-names> ] + ":" [ <model-names> ] + ":" [ <constant> ] + ":" [ <path> { "," <path> } ] + { ":" <special-mask> + ":" [ "!" ] <special-value> + ":" <word-nr> } + <nl> + ; + + + <path> ::= <int> "," <int> ;; + + <option> ::= + <reserved-options> + | <code-options> + | <optimize-options> + | <decode-options> + | <constant> + | <search-options> + ; + + <reserved-options> ::= "zero-reserved" ; + <gen-options> ::= "array" | "switch" | "padded-switch" | "goto-switch" ; + <optimize-options> ::= "duplicate" | "combine" + <decode-options> ::= "normal" | "boolean" ; + <search-options> ::= "constants" | "variables" | "mixed" + + Ignore the below: + + + The instruction decode table contains rules that dictate how igen + is going to firstly break down the opcode table and secondly + + 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. + + <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 instruction 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_reserved> + + Treat `/' (reserved) fields as a constant (zero) 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). Or a branch table (val 3). + + <special_mask> + <special_value> + <special_rule> + <special_constant> + + 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 + 3: boolean expansion of equality of special constant + + */ + + +typedef enum { + normal_decode_rule, + boolean_rule, +} decode_special_type; + + +typedef enum { + invalid_gen, + array_gen, + switch_gen, + padded_switch_gen, + goto_switch_gen, +} decode_gen_type; + + +enum { + decode_cond_mask_field, + decode_cond_value_field, + decode_cond_word_nr_field, + nr_decode_cond_fields, +}; + +typedef struct _decode_path decode_path; +struct _decode_path { + int opcode_nr; + decode_path *parent; +}; + +typedef struct _decode_path_list decode_path_list; +struct _decode_path_list { + decode_path *path; + decode_path_list *next; +}; + + +typedef struct _decode_cond decode_cond; +struct _decode_cond { + int word_nr; + int mask[max_insn_bit_size]; + int value[max_insn_bit_size]; + int is_equal; + decode_cond *next; +}; + +typedef enum { + decode_find_mixed, + decode_find_constants, + decode_find_strings, +} decode_search_type; + +enum { + decode_options_field, + decode_first_field, + decode_last_field, + decode_force_first_field, + decode_force_last_field, + decode_constant_field_names_field, + decode_word_nr_field, + decode_format_names_field, + decode_model_names_field, + decode_paths_field, + nr_decode_fields, + min_nr_decode_fields = decode_last_field + 1, +}; + + +typedef struct _decode_table decode_table; +struct _decode_table { + line_ref *line; + decode_special_type type; + decode_gen_type gen; + decode_search_type search; + int first; + int last; + int force_first; + int force_last; + filter *constant_field_names; + int word_nr; + /* if a boolean */ + unsigned constant; + /* options */ + int with_zero_reserved; + int with_duplicates; + int with_combine; + /* conditions on the rule being applied */ + decode_path_list *paths; + filter *format_names; + filter *model_names; + decode_cond *conditions; + decode_table *next; +}; + + +extern decode_table *load_decode_table +(char *file_name); + +extern int decode_table_max_word_nr +(decode_table *rule); + +extern void dump_decode_rule +(lf *file, + char *prefix, + decode_table *rule, + char *suffix); |