kvisc/vm/in/arith.c

// The OS/K Team licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#include <in/instrs.h>

IMPL_COND(sgn);
IMPL_COND(inc);
IMPL_COND(dec);
IMPL_COND(add);
IMPL_COND(sub);
IMPL_COND(mul);
IMPL_COND(div);
IMPL_COND(mod);
IMPL_COND(mul2);
IMPL_COND(div2);

//--------------------------------------------------------------------------

IMPL_START_1(inc)
{
    if (v1 == LONG_MAX) flg |= OF;
    else flg &= ~OF;

    v1++;
}
IMPL_OUT_ZSF;

IMPL_START_1(dec)
{
    if (v1 == LONG_MIN) flg |= OF;
    else flg &= ~OF;

    v1--;
}
IMPL_OUT_ZSF;

//--------------------------------------------------------------------------

IMPL_START_2(add)
{
    if (v1 + v2 < v1) flg |= OF;
    else flg &= ~OF;

    if ( ((v2 > 0) && (v1 > LONG_MAX - v2))
      || ((v2 < 0) && (v1 < LONG_MIN - v2)) )
         flg |= CF;
    else flg &= ~CF;

    v1 += v2;
}
IMPL_OUT_ZSF;

IMPL_START_2(sub)
{
    if (v1 < v2) flg |= CF;
    else flg &= ~CF;

    if ( ((v2 < 0) && (v1 > LONG_MAX + v2))
      || ((v2 > 0) && (v1 < LONG_MIN + v2)) )
         flg |= OF;
    else flg &= ~OF;

    v1 -= v2;
}
IMPL_OUT_ZSF;

//
// i_sub but discards result
//
IMPL_START_2(cmp)
{
    if (v1 < v2) flg |= CF;
    else flg &= ~CF;

    if ( ((v2 < 0) && (v1 > LONG_MAX + v2))
      || ((v2 > 0) && (v1 < LONG_MIN + v2)) )
        flg |= OF;
    else flg &= ~OF;

    SET_ZSF(v1 - v2);
}
IMPL_END;

//--------------------------------------------------------------------------

IMPL_START_2(mul)
{
    v1 *= v2;
}
IMPL_OUT;

IMPL_START_1(mul2)
{
    // Adapted from www.codeproject.com/Tips/618570/UInt-Multiplication-Squaring
    ulong v2 = v1;
    v1 = rax;

    ulong u1 = (v1 & 0xffffffff);
    ulong u2 = (v2 & 0xffffffff);
    ulong t = (u1 * u2);
    ulong w3 = (t & 0xffffffff);
    ulong k = (t >> 32);

    v1 >>= 32;
    t = (v1 * u2) + k;
    k = (t & 0xffffffff);
    ulong w1 = (t >> 32);

    v2 >>= 32;
    t = (u1 * v2) + k;
    k = (t >> 32);

    rdx = (v1 * v2) + w1 + k;
    rax = (t << 32) + w3;
}
IMPL_END;

//--------------------------------------------------------------------------

IMPL_START_2(div)
{
    v1 /= v2;
}
IMPL_OUT;

IMPL_START_2(mod)
{
    v1 %= v2;
}
IMPL_OUT;

IMPL_START_1(div2)
{
    rdx = rax % v1;
    rax = rax / v1;
}
IMPL_END;

//--------------------------------------------------------------------------

IMPL_START_2(sgn)
{
    if (v2 == 0) v1 = 0;

    else if ((long)v2 > 0) {
        flg &= ~CF;
        v1 = 1;
    }

    else {
        flg |= CF;
        v1 = (ulong)-1L;
    }
}
IMPL_OUT_ZSF;

IMPL_START_1(neg)
{
    if (v1 == 0) flg |= CF;

    else {
        flg &= ~CF;

        if (v1 == LONG_MIN) flg |= OF;
        else flg &= ~OF;
    }

    v1 = ~v1 + 1;
}
IMPL_OUT_ZSF;