Fixed const2big performance bug

diff --git a/kernel/calc.cc b/kernel/calc.cc
index aa3e8b919505702a87340c51449277ac92b40293..99980e92d70b88789afb1a1431e09c52ea06ab4f 100644 (file)
--- a/kernel/calc.cc
+++ b/kernel/calc.cc
@@ -41,21 +41,28 @@ static void extend_u0(RTLIL::Const &arg, int width, bool is_signed)
 
 static BigInteger const2big(const RTLIL::Const &val, bool as_signed, int &undef_bit_pos)
 {
-       BigInteger result = 0, this_bit = 1;
-       for (size_t i = 0; i < val.bits.size(); i++) {
-               if (val.bits[i] == RTLIL::State::S1) {
-                       if (as_signed && i+1 == val.bits.size())
-                               result -= this_bit;
-                       else
-                               result += this_bit;
-               }
-               else if (val.bits[i] != RTLIL::State::S0) {
-                       if (undef_bit_pos < 0)
-                               undef_bit_pos = i;
-               }
-               this_bit *= 2;
+       BigUnsigned mag;
+
+       BigInteger::Sign sign = BigInteger::positive;
+       State inv_sign_bit = RTLIL::State::S1;
+       size_t num_bits = val.bits.size();
+
+       if (as_signed && num_bits && val.bits[num_bits-1] == RTLIL::State::S1) {
+               inv_sign_bit = RTLIL::State::S0;
+               sign = BigInteger::negative;
+               num_bits--;
        }
-       return result;
+
+       for (size_t i = 0; i < num_bits; i++)
+               if (val.bits[i] == RTLIL::State::S0 || val.bits[i] == RTLIL::State::S1)
+                       mag.setBit(i, val.bits[i] == inv_sign_bit);
+               else if (undef_bit_pos < 0)
+                       undef_bit_pos = i;
+
+       if (sign == BigInteger::negative)
+               mag += 1;
+
+       return BigInteger(mag, sign);
 }
 
 static RTLIL::Const big2const(const BigInteger &val, int result_len, int undef_bit_pos)