yosys/backends/functional/cxx_runtime/sim.h

/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2024  Emily Schmidt <emily@yosyshq.com>
 *
 *  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 SIM_H
#define SIM_H

#include <array>
#include <cassert>

template<size_t n>
class Signal {
    template<size_t m> friend class Signal;
    std::array<bool, n> _bits;
public:
    Signal() { }
    Signal(uint32_t val)
    {
        for(size_t i = 0; i < n; i++)
            if(i < 32)
                _bits[i] = val & (1<<i);
            else
                _bits[i] = false;
    }

    Signal(std::initializer_list<uint32_t> vals)
    {
        size_t k, i;

        k = 0;
        for (auto val : vals) {
            for(i = 0; i < 32; i++)
                if(i + k < n)
                    _bits[i + k] = val & (1<<i);
            k += 32;
        }
        for(; k < n; k++)
            _bits[k] = false;
    }

    template<typename T>
    static Signal from_array(T vals)
    {
        size_t k, i;
        Signal ret;

        k = 0;
        for (auto val : vals) {
            for(i = 0; i < 32; i++)
                if(i + k < n)
                    ret._bits[i + k] = val & (1<<i);
            k += 32;
        }
        for(; k < n; k++)
            ret._bits[k] = false;
        return ret;
    }

    static Signal from_signed(int32_t val)
    {
        Signal<n> ret;
        for(size_t i = 0; i < n; i++)
            if(i < 32)
                ret._bits[i] = val & (1<<i);
            else
                ret._bits[i] = val < 0;
        return ret;
    }
    static Signal repeat(bool b)
    {
        Signal<n> ret;
        for(size_t i = 0; i < n; i++)
            ret._bits[i] = b;
        return ret;
    }

    int size() const { return n; }
    bool operator[](int i) const { assert(n >= 0 && i < n); return _bits[i]; }

    template<size_t m>
    Signal<m> slice(size_t offset) const
    {
        Signal<m> ret;

        assert(offset + m <= n);
        std::copy(_bits.begin() + offset, _bits.begin() + offset + m, ret._bits.begin());
        return ret;
    }

    bool any() const
    {
        for(int i = 0; i < n; i++)
            if(_bits[i])
                return true;
        return false;
    }

    bool all() const
    {
        for(int i = 0; i < n; i++)
            if(!_bits[i])
                return false;
        return true;
    }

    bool parity() const
    {
        bool result = false;
        for(int i = 0; i < n; i++)
            result ^= _bits[i];
        return result;
    }

    bool sign() const { return _bits[n-1]; }

    template<typename T>
    T as_numeric() const
    {
        T ret = 0;
        for(size_t i = 0; i < std::min<size_t>(sizeof(T) * 8, n); i++)
            if(_bits[i])
                ret |= ((T)1)<<i;
        return ret;
    }

    template<typename T>
    T as_numeric_clamped() const
    {
        for(size_t i = sizeof(T) * 8; i < n; i++)
            if(_bits[i])
                return ~((T)0);
        return as_numeric<T>();
    }

    uint32_t as_int() const { return as_numeric<uint32_t>(); }

    Signal<n> operator ~() const
    {
        Signal<n> ret;
        for(size_t i = 0; i < n; i++)
            ret._bits[i] = !_bits[i];
        return ret;
    }

    Signal<n> operator -() const
    {
        Signal<n> ret;
        bool carry = true;
        for(size_t i = 0; i < n; i++) {
            int r = !_bits[i] + carry;
            ret._bits[i] = (r & 1) != 0;
            carry = (r >> 1) != 0;
        }
        return ret;
    }

    Signal<n> operator +(Signal<n> const &b) const
    {
        Signal<n> ret;
        size_t i;
        int x = 0;
        for(i = 0; i < n; i++){
            x += (int)_bits[i] + (int)b._bits[i];
            ret._bits[i] = x & 1;
            x >>= 1;
        }
        return ret;
    }

    Signal<n> operator -(Signal<n> const &b) const
    {
        Signal<n> ret;
        int x = 1;
        for(size_t i = 0; i < n; i++){
            x += (int)_bits[i] + (int)!b._bits[i];
            ret._bits[i] = x & 1;
            x >>= 1;
        }
        return ret;
    }

    bool operator ==(Signal<n> const &b) const
    {
        for(size_t i = 0; i < n; i++)
            if(_bits[i] != b._bits[i])
                return false;
        return true;
    }

    bool operator >=(Signal<n> const &b) const
    {
        for(size_t i = n; i-- != 0; )
            if(_bits[i] != b._bits[i])
                return _bits[i];
        return true;
    }

    bool operator >(Signal<n> const &b) const
    {
        for(size_t i = n; i-- != 0; )
            if(_bits[i] != b._bits[i])
                return _bits[i];
        return false;
    }

    bool operator !=(Signal<n> const &b) const { return !(*this == b); }
    bool operator <=(Signal<n> const &b) const { return b <= *this; }
    bool operator <(Signal<n> const &b) const { return b < *this; }

    bool signed_greater_than(Signal<n> const &b) const
    {
        if(_bits[n-1] != b._bits[n-1])
            return b._bits[n-1];
        return *this > b;
    }

    bool signed_greater_equal(Signal<n> const &b) const
    {
        if(_bits[n-1] != b._bits[n-1])
            return b._bits[n-1];
        return *this >= b;
    }

    Signal<n> operator &(Signal<n> const &b) const
    {
        Signal<n> ret;
        for(size_t i = 0; i < n; i++)
            ret._bits[i] = _bits[i] && b._bits[i];
        return ret;
    }

    Signal<n> operator |(Signal<n> const &b) const
    {
        Signal<n> ret;
        for(size_t i = 0; i < n; i++)
            ret._bits[i] = _bits[i] || b._bits[i];
        return ret;
    }

    Signal<n> operator ^(Signal<n> const &b) const
    {
        Signal<n> ret;
        for(size_t i = 0; i < n; i++)
            ret._bits[i] = _bits[i] != b._bits[i];
        return ret;
    }

    template<size_t nb>
    Signal<n> operator <<(Signal<nb> const &b) const
    {
        Signal<n> ret = 0;
        size_t amount = b.template as_numeric_clamped<size_t>();
        if(amount < n)
            std::copy(_bits.begin(), _bits.begin() + (n - amount), ret._bits.begin() + amount);
        return ret;
    }

    template<size_t nb>
    Signal<n> operator >>(Signal<nb> const &b) const
    {
        Signal<n> ret = 0;
        size_t amount = b.template as_numeric_clamped<size_t>();
        if(amount < n)
            std::copy(_bits.begin() + amount, _bits.end(), ret._bits.begin());
        return ret;
    }

    template<size_t nb>
    Signal<n> arithmetic_shift_right(Signal<nb> const &b) const
    {
        Signal<n> ret = Signal::repeat(sign());
        size_t amount = b.template as_numeric_clamped<size_t>();
        if(amount < n)
            std::copy(_bits.begin() + amount, _bits.end(), ret._bits.begin());
        return ret;
    }

    template<size_t ns>
    Signal<n> pmux(Signal<n*ns> const &b, Signal<ns> const &s) const
    {
        bool found;
        Signal<n> ret;

        found = false;
        ret = *this;
        for(size_t i = 0; i < ns; i++){
            if(s._bits[i]){
                if(found)
                    return 0;
                found = true;
                ret = b.template slice<n>(n * i);
            }
        }
        return ret;
    }

    template<size_t m>
    Signal<n+m> concat(Signal<m> const& b) const
    {
        Signal<n + m> ret;
        std::copy(_bits.begin(), _bits.end(), ret._bits.begin());
        std::copy(b._bits.begin(), b._bits.end(), ret._bits.begin() + n);
        return ret;
    }

    template<size_t m>
    Signal<m> zero_extend() const
    {
        assert(m >= n);
        Signal<m> ret = 0;
        std::copy(_bits.begin(), _bits.end(), ret._bits.begin());
        return ret;
    }

    template<size_t m>
    Signal<m> sign_extend() const
    {
        assert(m >= n);
        Signal<m> ret = Signal<m>::repeat(sign());
        std::copy(_bits.begin(), _bits.end(), ret._bits.begin());
        return ret;
    }
};

template<size_t a, size_t d>
class Memory {
    std::array<Signal<d>, 1<<a> _contents;
public:
    Signal<d> read(Signal<a> addr) const
    {
        return _contents[addr.template as_numeric<size_t>()];
    }
    Memory write(Signal<a> addr, Signal<d> data) const
    {
        Memory ret = *this;
        ret._contents[addr.template as_numeric<size_t>()] = data;
        return ret;
    }
};

#endif