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

#include "instrs.h"
#include "arch_i.h"

//
// Unsigned arithmetic instructions
//

IMPL_START_2(add)
{
    v1 += v2;
}
IMPL_OUT;

IMPL_START_2(sub)
{
    v1 -= v2;
}
IMPL_OUT;

IMPL_START_1(mul)
{
    // Adapted from www.codeproject.com/Tips/618570/UInt-Multiplication-Squaring
    ulong v2 = v1;
    v1 = ctx->r[RAX].val;

    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);
    
    ctx->r[RDX].val = (v1 * v2) + w1 + k;
    ctx->r[RAX].val = (t << 32) + w3;
}
IMPL_END;

IMPL_START_1(div)
{
    ctx->r[RDX].val = ctx->r[RAX].val % v1;
    ctx->r[RAX].val = ctx->r[RAX].val / v1;
}
IMPL_END;

IMPL_START_1(inc)
{
    v1++;
}
IMPL_OUT;

IMPL_START_1(dec)
{
    v1--;
}
IMPL_OUT;