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/*
 *  nextpnr -- Next Generation Place and Route
 *
 *  Copyright (C) 2021  Symbiflow Authors
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

#ifndef NEXTPNR_H
#error Include "luts.h" via "nextpnr.h" only.
#endif

#include "dynamic_bitarray.h"

#ifndef LUTS_H
#define LUTS_H

NEXTPNR_NAMESPACE_BEGIN

struct CellInfo;
struct Context;

enum LogicLevel {
    LL_Zero,
    LL_One,
    LL_DontCare
};

struct LutCell {
    // LUT cell pins for equation, LSB first.
    std::vector<IdString> pins;
    std::unordered_set<IdString> lut_pins;
    std::unordered_set<IdString> vcc_pins;
    nextpnr::DynamicBitarray<> equation;
};

struct LutBel {
    // LUT BEL pins to LUT array index.
    std::vector<IdString> pins;
    std::unordered_map<IdString, size_t> pin_to_index;

    // What part of the LUT equation does this LUT output use?
    // This assumes contiguous LUT bits.
    uint32_t low_bit;
    uint32_t high_bit;

    int32_t min_pin;
    int32_t max_pin;
};

// Work forward from cell definition and cell -> bel pin map and check that 
// equation is valid.
void check_equation(
        const LutCell & lut_cell,
        const std::unordered_map<IdString, IdString> &cell_to_bel_map,
        const LutBel & lut_bel,
        const std::vector<LogicLevel> &equation,
        uint32_t used_pins);

struct LutElement {
    size_t width;
    std::unordered_map<IdString, LutBel> lut_bels;

    void compute_pin_order();

    std::vector<IdString> pins;
    std::unordered_map<IdString, size_t> pin_to_index;
};

struct LutMapper {
    LutMapper(const LutElement & element) : element(element) {}
    const LutElement & element;

    std::vector<CellInfo*> cells;

    bool remap_luts(const Context *ctx);
};

// Rotate and merge a LUT equation into an array of levels.
//
// If a conflict arises, return false and result is in an indeterminate state.
bool rotate_and_merge_lut_equation(std::vector<LogicLevel> * result,
        const LutBel & lut_bel,
        const nextpnr::DynamicBitarray<> &old_equation,
        const std::vector<size_t> &pin_map,
        uint32_t used_pins);

NEXTPNR_NAMESPACE_END

#endif /* LUTS_H */