-- Copyright (C) 2015 Tomoyuki Fujimori <moyu@dromozoa.com>
--
-- This file is part of dromozoa-commons.
--
-- dromozoa-commons 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.
--
-- dromozoa-commons 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 dromozoa-commons.  If not, see <http://www.gnu.org/licenses/>.

local lua_version_num = require "dromozoa.commons.lua_version_num"

local function add(a, b, x, ...)
  local c = (a + b) % 0x100000000
  if x == nil then
    return c
  else
    return add(c, x, ...)
  end
end

local function sub(a, b)
  return (a - b) % 0x100000000
end

local function mul(a, b, x, ...)
  local a1 = a % 0x10000
  local a2 = (a - a1) / 0x10000
  local c1 = a1 * b
  local c2 = a2 * b % 0x10000
  local c = (c1 + c2 * 0x10000) % 0x100000000
  if x == nil then
    return c
  else
    return mul(c, x, ...)
  end
end

local function div(a, b)
  local c = a / b
  return c - c % 1
end

local function mod(a, b)
  return a % b
end

local function byte(v, endian)
  local d = v % 0x100
  local v = (v - d) / 0x100
  local c = v % 0x100
  local v = (v - c) / 0x100
  local b = v % 0x100
  local a = (v - b) / 0x100
  if endian == ">" then
    return a, b, c, d
  else
    return d, c, b, a
  end
end

local function char(v, endian)
  return string.char(byte(v, endian))
end

local function read(handle, n, endian)
  local a, b, c, d = handle:read(4):byte(1, 4)
  local v
  if endian == ">" then
    v = a * 0x1000000 + b * 0x10000 + c * 0x100 + d
  else
    v = d * 0x1000000 + c * 0x10000 + b * 0x100 + a
  end
  if n == nil or n == 1 then
    return v
  else
    return v, read(handle, n - 1, endian)
  end
end

if lua_version_num >= 503 then
  return assert(load([[
    local function add(a, b, x, ...)
      local c = a + b & 0xffffffff
      if x == nil then
        return c
      else
        return add(c, x, ...)
      end
    end

    local function mul(a, b, x, ...)
      local c = a * b & 0xffffffff
      if x == nil then
        return c
      else
        return mul(c, x, ...)
      end
    end

    local function band(a, b, x, ...)
      local c = a & b
      if x == nil then
        return c
      else
        return band(c, x, ...)
      end
    end

    local function bor(a, b, x, ...)
      local c = a | b
      if x == nil then
        return c
      else
        return bor(c, x, ...)
      end
    end

    local function bxor(a, b, x, ...)
      local c = a ~ b
      if x == nil then
        return c
      else
        return bxor(c, x, ...)
      end
    end

    local function read(handle, n, endian)
      local v
      if endian == ">" then
        v = (">I4"):unpack(handle:read(4))
      else
        v = ("<I4"):unpack(handle:read(4))
      end
      if n == nil or n == 1 then
        return v
      else
        return v, read(handle, n - 1, endian)
      end
    end

    return {
      add = add;
      sub = function (a, b)
        return a - b & 0xffffffff
      end;
      mul = mul;
      div = function (a, b)
        return a // b
      end;
      mod = function (a, b)
        return a % b
      end;
      band = band;
      bor = bor;
      bxor = bxor;
      shl = function (a, b)
        return a << b & 0xffffffff
      end;
      shr = function (a, b)
        return a >> b
      end;
      bnot = function (v)
        return ~v & 0xffffffff
      end;
      rotl = function (a, b)
        return (a << b | a >> 32 - b) & 0xffffffff
      end;
      rotr = function (a, b)
        return (a >> b | a << 32 - b) & 0xffffffff
      end;
      byte = function (v, endian)
        if endian == ">" then
          local a, b, c, d = ("BBBB"):unpack((">I4"):pack(v))
          return a, b, c, d
        else
          local a, b, c, d = ("BBBB"):unpack(("<I4"):pack(v))
          return a, b, c, d
        end
      end;
      char = function (v, endian)
        if endian == ">" then
          return (">I4"):pack(v)
        else
          return ("<I4"):pack(v)
        end
      end;
      read = read;
    }
  ]]))()
elseif bit32 then
  return {
    add = add;
    sub = sub;
    mul = mul;
    div = div;
    mod = mod;
    band = bit32.band;
    bor = bit32.bor;
    bxor = bit32.bxor;
    shl = bit32.lshift;
    shr = bit32.rshift;
    bnot = bit32.bnot;
    rotl = bit32.lrotate;
    rotr = bit32.rrotate;
    byte = byte;
    char = char;
    read = read;
  }
elseif bit then
  local bit_band = bit.band
  local bit_bor = bit.bor
  local bit_bxor = bit.bxor
  local bit_lshift = bit.lshift
  local bit_rshift = bit.rshift
  local bit_bnot = bit.bnot
  local bit_rol = bit.rol
  local bit_ror = bit.ror
  return {
    add = add;
    sub = sub;
    mul = mul;
    div = div;
    mod = mod;
    band = function (...)
      return bit_band(...) % 0x100000000
    end;
    bor = function (...)
      return bit_bor(...) % 0x100000000
    end;
    bxor = function (...)
      return bit_bxor(...) % 0x100000000
    end;
    shl = function (a, b)
      return bit_lshift(a, b) % 0x100000000
    end;
    shr = function (a, b)
      return bit_rshift(a, b) % 0x100000000
    end;
    bnot = function (v)
      return bit_bnot(v) % 0x100000000
    end;
    rotl = function (a, b)
      return bit_rol(a, b) % 0x100000000
    end;
    rotr = function (a, b)
      return bit_ror(a, b) % 0x100000000
    end;
    byte = byte;
    char = char;
    read = read;
  }
else
  local function optimize_unary(fn)
    local t = {}
    for v = 0, 255 do
      t[v] = fn(v) % 0x100
    end
    return function (v)
      local v1 = v % 0x100 v = (v - v1) / 0x100
      local v2 = v % 0x100 v = (v - v2) / 0x100
      local v3 = v % 0x100 v = (v - v3) / 0x100
      return t[v] * 0x1000000 + t[v3] * 0x10000 + t[v2] * 0x100 + t[v1]
    end
  end

  local function optimize_binary(fn)
    local t = {}
    for a = 0, 15 do
      t[a] = {}
      for b = 0, 15 do
        t[a][b] = fn(a, b) % 0x100
      end
    end
    local function f(a, b, x, ...)
      local a1 = a % 0x10 a = (a - a1) / 0x10
      local a2 = a % 0x10 a = (a - a2) / 0x10
      local a3 = a % 0x10 a = (a - a3) / 0x10
      local a4 = a % 0x10 a = (a - a4) / 0x10
      local a5 = a % 0x10 a = (a - a5) / 0x10
      local a6 = a % 0x10 a = (a - a6) / 0x10
      local a7 = a % 0x10 a = (a - a7) / 0x10
      local b1 = b % 0x10 b = (b - b1) / 0x10
      local b2 = b % 0x10 b = (b - b2) / 0x10
      local b3 = b % 0x10 b = (b - b3) / 0x10
      local b4 = b % 0x10 b = (b - b4) / 0x10
      local b5 = b % 0x10 b = (b - b5) / 0x10
      local b6 = b % 0x10 b = (b - b6) / 0x10
      local b7 = b % 0x10 b = (b - b7) / 0x10
      local c = t[a][b] * 0x10000000 + t[a7][b7] * 0x1000000 + t[a6][b6] * 0x100000 + t[a5][b5] * 0x10000 + t[a4][b4] * 0x1000 + t[a3][b3] * 0x100 + t[a2][b2] * 0x10 + t[a1][b1]
      if x == nil then
        return c
      else
        return f(c, x, ...)
      end
    end
    return f
  end

  local function band(a, b, x, ...)
    local c = 0
    local d = 1
    for i = 1, 31 do
      local a1 = a % 2
      local b1 = b % 2
      if a1 + b1 == 2 then
        c = c + d
      end
      a = (a - a1) / 2
      b = (b - b1) / 2
      d = d * 2
    end
    if a + b == 2 then
      c = c + d
    end
    if x == nil then
      return c
    else
      return band(c, x, ...)
    end
  end

  local function bor(a, b, x, ...)
    local c = 0
    local d = 1
    for i = 1, 31 do
      local a1 = a % 2
      local b1 = b % 2
      if a1 + b1 ~= 0 then
        c = c + d
      end
      a = (a - a1) / 2
      b = (b - b1) / 2
      d = d * 2
    end
    if a + b ~= 0 then
      c = c + d
    end
    if x == nil then
      return c
    else
      return bor(c, x, ...)
    end
  end

  local function bxor(a, b, x, ...)
    local c = 0
    local d = 1
    for i = 1, 31 do
      local a1 = a % 2
      local b1 = b % 2
      if a1 ~= b1 then
        c = c + d
      end
      a = (a - a1) / 2
      b = (b - b1) / 2
      d = d * 2
    end
    if a ~= b then
      c = c + d
    end
    if x == nil then
      return c
    else
      return bxor(c, x, ...)
    end
  end

  local function bnot(v)
    local c = 0
    local d = 1
    for i = 1, 31 do
      local v1 = v % 2
      if v1 == 0 then
        c = c + d
      end
      v = (v - v1) / 2
      d = d * 2
    end
    if v == 0 then
      c = c + d
    end
    return c
  end

  local function shl(a, b)
    local b1 = 2 ^ b
    local b2 = 0x100000000 / b1
    return a % b2 * b1
  end

  local function shr(a, b)
    local b1 = 2 ^ b
    local c = a / b1
    return c - c % 1
  end

  local function rotl(a, b)
    local b1 = 2 ^ b
    local b2 = 0x100000000 / b1
    local c1 = a % b2
    local c2 = (a - c1) / b2
    return c1 * b1 + c2
  end

  local function rotr(a, b)
    local b1 = 2 ^ b
    local b2 = 0x100000000 / b1
    local c1 = a % b1
    local c2 = (a - c1) / b1
    return c1 * b2 + c2
  end

  return {
    add = add;
    sub = sub;
    mul = mul;
    div = div;
    mod = mod;
    band = optimize_binary(band);
    bor = optimize_binary(bor);
    bxor = optimize_binary(bxor);
    shl = shl;
    shr = shr;
    bnot = optimize_unary(bnot);
    rotl = rotl;
    rotr = rotr;
    byte = byte;
    char = char;
    read = read;
  }
end