/**
 * Compiler implementation of the
 * $(LINK2 http://www.dlang.org, D programming language).
 *
 * Copyright:   Copyright (c) 1999-2016 by Digital Mars, All Rights Reserved
 * Authors:     $(LINK2 http://www.digitalmars.com, Walter Bright)
 * License:     $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
 * Source:      $(DMDSRC _builtin.d)
 */

module ddmd.builtin;

import core.stdc.math;
import core.stdc.string;
import ddmd.arraytypes;
import ddmd.dmangle;
import ddmd.errors;
import ddmd.expression;
import ddmd.func;
import ddmd.globals;
import ddmd.mtype;
import ddmd.root.ctfloat;
import ddmd.root.stringtable;
import ddmd.tokens;

private:

/**
 * Handler for evaluating builtins during CTFE.
 *
 * Params:
 *  loc = The call location, for error reporting.
 *  fd = The callee declaration, e.g. to disambiguate between different overloads
 *       in a single handler (LDC).
 *  arguments = The function call arguments.
 * Returns:
 *  An Expression containing the return value of the call.
 */
extern (C++) alias builtin_fp = Expression function(Loc loc, FuncDeclaration fd, Expressions* arguments);

__gshared StringTable builtins;

public extern (C++) void add_builtin(const(char)* mangle, builtin_fp fp)
{
    builtins.insert(mangle, strlen(mangle), cast(void*)fp);
}

builtin_fp builtin_lookup(const(char)* mangle)
{
    if (const sv = builtins.lookup(mangle, strlen(mangle)))
        return cast(builtin_fp)sv.ptrvalue;
    return null;
}

extern (C++) Expression eval_unimp(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    return null;
}

extern (C++) Expression eval_sin(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    return new RealExp(loc, CTFloat.sin(arg0.toReal()), arg0.type);
}

extern (C++) Expression eval_cos(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    return new RealExp(loc, CTFloat.cos(arg0.toReal()), arg0.type);
}

extern (C++) Expression eval_tan(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    return new RealExp(loc, CTFloat.tan(arg0.toReal()), arg0.type);
}

extern (C++) Expression eval_sqrt(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    return new RealExp(loc, CTFloat.sqrt(arg0.toReal()), arg0.type);
}

extern (C++) Expression eval_fabs(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    return new RealExp(loc, CTFloat.fabs(arg0.toReal()), arg0.type);
}

extern (C++) Expression eval_bsf(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKint64);
    uinteger_t n = arg0.toInteger();
    if (n == 0)
        error(loc, "bsf(0) is undefined");
    n = (n ^ (n - 1)) >> 1; // convert trailing 0s to 1, and zero rest
    int k = 0;
    while (n)
    {
        ++k;
        n >>= 1;
    }
    return new IntegerExp(loc, k, Type.tint32);
}

extern (C++) Expression eval_bsr(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKint64);
    uinteger_t n = arg0.toInteger();
    if (n == 0)
        error(loc, "bsr(0) is undefined");
    int k = 0;
    while (n >>= 1)
    {
        ++k;
    }
    return new IntegerExp(loc, k, Type.tint32);
}

extern (C++) Expression eval_bswap(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKint64);
    uinteger_t n = arg0.toInteger();
    enum BYTEMASK = 0x00FF00FF00FF00FFL;
    enum SHORTMASK = 0x0000FFFF0000FFFFL;
    enum INTMASK = 0x0000FFFF0000FFFFL;
    // swap adjacent ubytes
    n = ((n >> 8) & BYTEMASK) | ((n & BYTEMASK) << 8);
    // swap adjacent ushorts
    n = ((n >> 16) & SHORTMASK) | ((n & SHORTMASK) << 16);
    TY ty = arg0.type.toBasetype().ty;
    // If 64 bits, we need to swap high and low uints
    if (ty == Tint64 || ty == Tuns64)
        n = ((n >> 32) & INTMASK) | ((n & INTMASK) << 32);
    return new IntegerExp(loc, n, arg0.type);
}

extern (C++) Expression eval_popcnt(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKint64);
    uinteger_t n = arg0.toInteger();
    int cnt = 0;
    while (n)
    {
        cnt += (n & 1);
        n >>= 1;
    }
    return new IntegerExp(loc, cnt, arg0.type);
}

extern (C++) Expression eval_yl2x(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    Expression arg1 = (*arguments)[1];
    assert(arg1.op == TOKfloat64);
    const x = arg0.toReal();
    const y = arg1.toReal();
    real_t result = 0;
    CTFloat.yl2x(&x, &y, &result);
    return new RealExp(loc, result, arg0.type);
}

extern (C++) Expression eval_yl2xp1(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    Expression arg0 = (*arguments)[0];
    assert(arg0.op == TOKfloat64);
    Expression arg1 = (*arguments)[1];
    assert(arg1.op == TOKfloat64);
    const x = arg0.toReal();
    const y = arg1.toReal();
    real_t result = 0;
    CTFloat.yl2xp1(&x, &y, &result);
    return new RealExp(loc, result, arg0.type);
}

public extern (C++) void builtin_init()
{
    builtins._init(47);
    // @safe @nogc pure nothrow real function(real)
    add_builtin("_D4core4math3sinFNaNbNiNfeZe", &eval_sin);
    add_builtin("_D4core4math3cosFNaNbNiNfeZe", &eval_cos);
    add_builtin("_D4core4math3tanFNaNbNiNfeZe", &eval_tan);
    add_builtin("_D4core4math4sqrtFNaNbNiNfeZe", &eval_sqrt);
    add_builtin("_D4core4math4fabsFNaNbNiNfeZe", &eval_fabs);
    add_builtin("_D4core4math5expm1FNaNbNiNfeZe", &eval_unimp);
    add_builtin("_D4core4math4exp21FNaNbNiNfeZe", &eval_unimp);
    // @trusted @nogc pure nothrow real function(real)
    add_builtin("_D4core4math3sinFNaNbNiNeeZe", &eval_sin);
    add_builtin("_D4core4math3cosFNaNbNiNeeZe", &eval_cos);
    add_builtin("_D4core4math3tanFNaNbNiNeeZe", &eval_tan);
    add_builtin("_D4core4math4sqrtFNaNbNiNeeZe", &eval_sqrt);
    add_builtin("_D4core4math4fabsFNaNbNiNeeZe", &eval_fabs);
    add_builtin("_D4core4math5expm1FNaNbNiNeeZe", &eval_unimp);
    add_builtin("_D4core4math4exp21FNaNbNiNeeZe", &eval_unimp);
    // @safe @nogc pure nothrow double function(double)
    add_builtin("_D4core4math4sqrtFNaNbNiNfdZd", &eval_sqrt);
    // @safe @nogc pure nothrow float function(float)
    add_builtin("_D4core4math4sqrtFNaNbNiNffZf", &eval_sqrt);
    // @safe @nogc pure nothrow real function(real, real)
    add_builtin("_D4core4math5atan2FNaNbNiNfeeZe", &eval_unimp);
    if (CTFloat.yl2x_supported)
    {
        add_builtin("_D4core4math4yl2xFNaNbNiNfeeZe", &eval_yl2x);
    }
    else
    {
        add_builtin("_D4core4math4yl2xFNaNbNiNfeeZe", &eval_unimp);
    }
    if (CTFloat.yl2xp1_supported)
    {
        add_builtin("_D4core4math6yl2xp1FNaNbNiNfeeZe", &eval_yl2xp1);
    }
    else
    {
        add_builtin("_D4core4math6yl2xp1FNaNbNiNfeeZe", &eval_unimp);
    }
    // @safe @nogc pure nothrow long function(real)
    add_builtin("_D4core4math6rndtolFNaNbNiNfeZl", &eval_unimp);
    // @safe @nogc pure nothrow real function(real)
    add_builtin("_D3std4math3sinFNaNbNiNfeZe", &eval_sin);
    add_builtin("_D3std4math3cosFNaNbNiNfeZe", &eval_cos);
    add_builtin("_D3std4math3tanFNaNbNiNfeZe", &eval_tan);
    add_builtin("_D3std4math4sqrtFNaNbNiNfeZe", &eval_sqrt);
    add_builtin("_D3std4math4fabsFNaNbNiNfeZe", &eval_fabs);
    add_builtin("_D3std4math5expm1FNaNbNiNfeZe", &eval_unimp);
    add_builtin("_D3std4math4exp21FNaNbNiNfeZe", &eval_unimp);
    // @trusted @nogc pure nothrow real function(real)
    add_builtin("_D3std4math3sinFNaNbNiNeeZe", &eval_sin);
    add_builtin("_D3std4math3cosFNaNbNiNeeZe", &eval_cos);
    add_builtin("_D3std4math3tanFNaNbNiNeeZe", &eval_tan);
    add_builtin("_D3std4math4sqrtFNaNbNiNeeZe", &eval_sqrt);
    add_builtin("_D3std4math4fabsFNaNbNiNeeZe", &eval_fabs);
    add_builtin("_D3std4math5expm1FNaNbNiNeeZe", &eval_unimp);
    add_builtin("_D3std4math4exp21FNaNbNiNeeZe", &eval_unimp);
    // @safe @nogc pure nothrow double function(double)
    add_builtin("_D3std4math4sqrtFNaNbNiNfdZd", &eval_sqrt);
    // @safe @nogc pure nothrow float function(float)
    add_builtin("_D3std4math4sqrtFNaNbNiNffZf", &eval_sqrt);
    // @safe @nogc pure nothrow real function(real, real)
    add_builtin("_D3std4math5atan2FNaNbNiNfeeZe", &eval_unimp);
    if (CTFloat.yl2x_supported)
    {
        add_builtin("_D3std4math4yl2xFNaNbNiNfeeZe", &eval_yl2x);
    }
    else
    {
        add_builtin("_D3std4math4yl2xFNaNbNiNfeeZe", &eval_unimp);
    }
    if (CTFloat.yl2xp1_supported)
    {
        add_builtin("_D3std4math6yl2xp1FNaNbNiNfeeZe", &eval_yl2xp1);
    }
    else
    {
        add_builtin("_D3std4math6yl2xp1FNaNbNiNfeeZe", &eval_unimp);
    }
    // @safe @nogc pure nothrow long function(real)
    add_builtin("_D3std4math6rndtolFNaNbNiNfeZl", &eval_unimp);
    // @safe @nogc pure nothrow int function(uint)
    add_builtin("_D4core5bitop3bsfFNaNbNiNfkZi", &eval_bsf);
    add_builtin("_D4core5bitop3bsrFNaNbNiNfkZi", &eval_bsr);
    // @safe @nogc pure nothrow int function(ulong)
    add_builtin("_D4core5bitop3bsfFNaNbNiNfmZi", &eval_bsf);
    add_builtin("_D4core5bitop3bsrFNaNbNiNfmZi", &eval_bsr);
    // @safe @nogc pure nothrow uint function(uint)
    add_builtin("_D4core5bitop5bswapFNaNbNiNfkZk", &eval_bswap);
    // @safe @nogc pure nothrow int function(uint)
    add_builtin("_D4core5bitop7_popcntFNaNbNiNfkZi", &eval_popcnt);
    // @safe @nogc pure nothrow ushort function(ushort)
    add_builtin("_D4core5bitop7_popcntFNaNbNiNftZt", &eval_popcnt);
    // @safe @nogc pure nothrow int function(ulong)
    if (global.params.is64bit)
        add_builtin("_D4core5bitop7_popcntFNaNbNiNfmZi", &eval_popcnt);
}

/**********************************
 * Determine if function is a builtin one that we can
 * evaluate at compile time.
 */
public extern (C++) BUILTIN isBuiltin(FuncDeclaration fd)
{
    if (fd.builtin == BUILTINunknown)
    {
        builtin_fp fp = builtin_lookup(mangleExact(fd));
        fd.builtin = fp ? BUILTINyes : BUILTINno;
    }
    return fd.builtin;
}

/**************************************
 * Evaluate builtin function.
 * Return result; NULL if cannot evaluate it.
 */
public extern (C++) Expression eval_builtin(Loc loc, FuncDeclaration fd, Expressions* arguments)
{
    if (fd.builtin == BUILTINyes)
    {
        builtin_fp fp = builtin_lookup(mangleExact(fd));
        assert(fp);
        return fp(loc, fd, arguments);
    }
    return null;
}
