mathlib.func

{-
  openlib.func – open-source extended library for Func

  Copyright (C) 2023 Continuation Team

  This file is part of openlib.func.

  openlib.func 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 3 of the License, or
  (at your option) any later version.

  openlib.func 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 openlib.func.  If not, see <https://www.gnu.org/licenses/>.
-}

#pragma version >=0.4.0;


int math::sqrt(int x) asm """
  <{
    //  x
    DUP             // x x
    IFNOTRET        // x
    181 PUSHINT     // x r=181
    s1 s1 PUSH2     // x r=181 xx xx
    128 PUSHPOW2    // x r=181 xx xx _1=340282366920938463463374607431768211456
    GEQ             // x r=181 xx _f
    IF:<{           // x r=181 xx
      128 RSHIFT#   // x r xx
      SWAP          // x xx r
      64 LSHIFT#    // x xx r
      SWAP          // x r xx
    }>              // x r xx
    DUP             // x r xx xx
    64 PUSHPOW2     // x r xx xx _2=18446744073709551616
    GEQ             // x r xx _f
    IF:<{           // x r xx
      64 RSHIFT#    // x r xx
      SWAP          // x xx r
      32 LSHIFT#    // x xx r
      SWAP          // x r xx
    }>              // x r xx
    DUP             // x r xx xx
    32 PUSHPOW2     // x r xx xx _3=4294967296
    GEQ             // x r xx _f
    IF:<{           // x r xx
      32 RSHIFT#    // x r xx
      SWAP          // x xx r
      16 LSHIFT#    // x xx r
      SWAP          // x r xx
    }>              // x r xx
    DUP             // x r xx xx
    16 PUSHPOW2     // x r xx xx _4=65536
    GEQ             // x r xx _f
    IF:<{           // x r xx
      16 RSHIFT#    // x r xx
      SWAP          // x xx r
      8 LSHIFT#     // x xx r
      SWAP          // x r xx
    }>              // x r xx
    16 PUSHPOW2     // x r xx _5=65536
    ADD             // x r _6
    MUL             // x r
    18 RSHIFT#      // x r
    {
      2DUP          // x r x r
      DIV           // x r _7
      ADD           // x r
      1 RSHIFT#     // x r
    } 7 times
    TUCK            // r x r
    DIV             // r r1
    2DUP            // r r1 r r1
    LESS            // r r1 _f
    -ROT CONDSELCHK // IF:<{ DROP }>ELSE<{ NIP }>
  }>c CALLREF // equivalent to inline_ref
""";