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/*
* Support functions for VHDL output.
*
* Copyright (C) 2008-2009 Nick Gasson (nick@nickg.me.uk)
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "vhdl_target.h"
#include "support.hh"
#include "state.hh"
#include <cassert>
#include <iostream>
void require_support_function(support_function_t f)
{
vhdl_scope *scope = get_active_entity()->get_arch()->get_scope();
if (!scope->have_declared(support_function::function_name(f)))
scope->add_decl(new support_function(f));
}
const char *support_function::function_name(support_function_t type)
{
switch (type) {
case SF_UNSIGNED_TO_BOOLEAN: return "Unsigned_To_Boolean";
case SF_SIGNED_TO_BOOLEAN: return "Signed_To_Boolean";
case SF_BOOLEAN_TO_LOGIC: return "Boolean_To_Logic";
case SF_REDUCE_OR: return "Reduce_OR";
case SF_REDUCE_AND: return "Reduce_AND";
case SF_REDUCE_XOR: return "Reduce_XOR";
case SF_REDUCE_XNOR: return "Reduce_XNOR";
case SF_TERNARY_LOGIC: return "Ternary_Logic";
case SF_TERNARY_UNSIGNED: return "Ternary_Unsigned";
case SF_TERNARY_SIGNED: return "Ternary_Signed";
case SF_LOGIC_TO_INTEGER: return "Logic_To_Integer";
case SF_SIGNED_TO_LOGIC: return "Signed_To_Logic";
case SF_UNSIGNED_TO_LOGIC: return "Unsigned_To_Logic";
default:
assert(false);
}
return "Invalid";
}
vhdl_type *support_function::function_type(support_function_t type)
{
switch (type) {
case SF_UNSIGNED_TO_BOOLEAN:
case SF_SIGNED_TO_BOOLEAN:
return vhdl_type::boolean();
case SF_BOOLEAN_TO_LOGIC:
case SF_REDUCE_OR:
case SF_REDUCE_AND:
case SF_REDUCE_XOR:
case SF_REDUCE_XNOR:
case SF_TERNARY_LOGIC:
case SF_SIGNED_TO_LOGIC:
case SF_UNSIGNED_TO_LOGIC:
return vhdl_type::std_logic();
case SF_TERNARY_SIGNED:
return new vhdl_type(VHDL_TYPE_SIGNED);
case SF_TERNARY_UNSIGNED:
return new vhdl_type(VHDL_TYPE_UNSIGNED);
case SF_LOGIC_TO_INTEGER:
return vhdl_type::integer();
}
assert(false);
return vhdl_type::boolean();
}
void support_function::emit_ternary(std::ostream &of, int level) const
{
of << nl_string(level) << "begin" << nl_string(indent(level))
<< "if T then return X; else return Y; end if;";
}
void support_function::emit_reduction(std::ostream &of, int level,
const char *op, char unit) const
{
// Emit a VHDL function emulating a Verilog reduction operator
// Where op is the corresponding VHDL operator and unit is the
// right-unit of the operator
of << "(X : std_logic_vector) return std_logic is"
<< nl_string(indent(level))
<< "variable R : std_logic := '" << unit << "';" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "for I in X'Range loop" << nl_string(indent(indent(level)))
<< "R := X(I) " << op << " R;" << nl_string(indent(level))
<< "end loop;" << nl_string(indent(level))
<< "return R;";
}
void support_function::emit(std::ostream &of, int level) const
{
of << nl_string(level) << "function " << function_name(type_);
switch (type_) {
case SF_UNSIGNED_TO_BOOLEAN:
of << "(X : unsigned) return Boolean is" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "return X /= To_Unsigned(0, X'Length);";
break;
case SF_SIGNED_TO_BOOLEAN:
of << "(X : signed) return Boolean is" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "return X /= To_Signed(0, X'Length);";
break;
case SF_BOOLEAN_TO_LOGIC:
of << "(B : Boolean) return std_logic is" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "if B then" << nl_string(indent(indent(level)))
<< "return '1';" << nl_string(indent(level))
<< "else" << nl_string(indent(indent(level)))
<< "return '0';" << nl_string(indent(level))
<< "end if;";
break;
case SF_UNSIGNED_TO_LOGIC:
of << "(X : unsigned) return std_logic is" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "return X(0);";
break;
case SF_SIGNED_TO_LOGIC:
of << "(X : signed) return std_logic is" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "return X(0);";
break;
case SF_REDUCE_OR:
emit_reduction(of, level, "or", '0');
break;
case SF_REDUCE_AND:
emit_reduction(of, level, "and", '1');
break;
case SF_REDUCE_XOR:
emit_reduction(of, level, "xor", '0');
break;
case SF_REDUCE_XNOR:
emit_reduction(of, level, "xnor", '0');
break;
case SF_TERNARY_LOGIC:
of << "(T : Boolean; X, Y : std_logic) return std_logic is";
emit_ternary(of, level);
break;
case SF_TERNARY_SIGNED:
of << "(T : Boolean; X, Y : signed) return signed is";
emit_ternary(of, level);
break;
case SF_TERNARY_UNSIGNED:
of << "(T : Boolean; X, Y : unsigned) return unsigned is";
emit_ternary(of, level);
break;
case SF_LOGIC_TO_INTEGER:
of << "(X : std_logic) return integer is" << nl_string(level)
<< "begin" << nl_string(indent(level))
<< "if X = '1' then return 1; else return 0; end if;";
break;
default:
assert(false);
}
of << nl_string(level) << "end function;";
}
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