mirror of
https://github.com/autc04/Retro68.git
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107 lines
2.7 KiB
C
107 lines
2.7 KiB
C
/* Plural expression evaluation.
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Copyright (C) 2000-2003, 2007, 2015-2016 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef STATIC
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#define STATIC static
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#endif
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/* Evaluate the plural expression and return an index value. */
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STATIC
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unsigned long int
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internal_function
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plural_eval (const struct expression *pexp, unsigned long int n)
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{
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switch (pexp->nargs)
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{
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case 0:
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switch (pexp->operation)
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{
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case var:
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return n;
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case num:
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return pexp->val.num;
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default:
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break;
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}
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/* NOTREACHED */
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break;
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case 1:
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{
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/* pexp->operation must be lnot. */
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unsigned long int arg = plural_eval (pexp->val.args[0], n);
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return ! arg;
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}
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case 2:
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{
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unsigned long int leftarg = plural_eval (pexp->val.args[0], n);
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if (pexp->operation == lor)
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return leftarg || plural_eval (pexp->val.args[1], n);
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else if (pexp->operation == land)
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return leftarg && plural_eval (pexp->val.args[1], n);
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else
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{
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unsigned long int rightarg = plural_eval (pexp->val.args[1], n);
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switch (pexp->operation)
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{
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case mult:
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return leftarg * rightarg;
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case divide:
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#if !INTDIV0_RAISES_SIGFPE
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if (rightarg == 0)
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raise (SIGFPE);
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#endif
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return leftarg / rightarg;
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case module:
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#if !INTDIV0_RAISES_SIGFPE
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if (rightarg == 0)
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raise (SIGFPE);
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#endif
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return leftarg % rightarg;
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case plus:
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return leftarg + rightarg;
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case minus:
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return leftarg - rightarg;
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case less_than:
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return leftarg < rightarg;
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case greater_than:
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return leftarg > rightarg;
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case less_or_equal:
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return leftarg <= rightarg;
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case greater_or_equal:
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return leftarg >= rightarg;
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case equal:
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return leftarg == rightarg;
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case not_equal:
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return leftarg != rightarg;
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default:
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break;
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}
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}
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/* NOTREACHED */
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break;
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}
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case 3:
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{
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/* pexp->operation must be qmop. */
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unsigned long int boolarg = plural_eval (pexp->val.args[0], n);
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return plural_eval (pexp->val.args[boolarg ? 1 : 2], n);
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}
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}
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/* NOTREACHED */
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return 0;
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}
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