// 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"

#define _NEED_ARCH_I
#include "arch_i.h"

IMPL_START_0(nop)
{
}
IMPL_END;

//
// Logical instructions
//

IMPL_START_2(and)
{
    v1 &= v2;
}
IMPL_OUT;

IMPL_START_2(or)
{
    v1 |= v2;
}
IMPL_OUT;

IMPL_START_2(xor)
{
    v1 ^= v2;
}
IMPL_OUT;

IMPL_START_2(shl)
{
    v1 <<= v2;
}
IMPL_OUT;

IMPL_START_2(shr)
{
    v1 >>= v2;
}
IMPL_OUT;

IMPL_START_1(not)
{
    v1 = ~v1;
}
IMPL_OUT;

//
// 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;

//
// Comparison instructions
//

IMPL_START_2(cmp)
{
    if (v1 == v2) {
        ctx->r[FLG].val |= ZF;
        ctx->r[FLG].val &= ~CF;
    }
    
    else if (v1 < v2) {
        ctx->r[FLG].val &= ~ZF;
        ctx->r[FLG].val |= CF;
    }

    else {
        ctx->r[FLG].val &= ~ZF;
        ctx->r[FLG].val &= ~CF;
    }
}
IMPL_END;

IMPL_START_2(test)
{
    ulong v = v1 & v2;
    
    if (v == 0) ctx->r[FLG].val |= ZF;
    else ctx->r[FLG].val &= ~ZF;
}
IMPL_END;

//
// Jump instructions
//

//
// Movement instructions
//

IMPL_START_2(mov)
{
    v1 = v2;
}
IMPL_OUT;

IMPL_START_2(xchg)
{
    ulong t = v1;
    v1 = v2;
    v2 = t;
}
IMPL_OUT;

IMPL_START_1(lea)
{
    assert(p2->mem);
    
    v1 = (p2->type == A_REG ? ctx->r[p2->val].val : p2->val) + p2->off;
}
IMPL_OUT;

//
// Stack manipulation instructions
//

IMPL_START_1(push)
{
    if (ctx->r[RSP].val % 8 > 0 || ctx->r[RBP].val % 8 > 0) {
       _except(ctx, E_STK, "Misaligned stack REGS");
    }

    if (ctx->r[RSP].val > ctx->r[RBP].val) {
        _except(ctx, E_STK, "RSP above RBP");
    }

    writemem64(ctx, v1, ctx->r[RSP].val);
    ctx->r[RSP].val -= 8;
}
IMPL_END;

IMPL_START_1(pop)
{
    if (ctx->r[RSP].val % 8 > 0 || ctx->r[RBP].val % 8 > 0) {
       _except(ctx, E_STK, "Misaligned stack REGS");
    }

    if (ctx->r[RSP].val >= ctx->r[RBP].val) {
        _except(ctx, E_STK, "RBP above RSP");
    }

    ctx->r[RSP].val += 8;
    v1 = readmem64(ctx, ctx->r[RSP].val);
}
IMPL_OUT;

IMPL_START_1(call)
{
    if (ctx->r[RSP].val % 8 > 0 || ctx->r[RBP].val % 8 > 0) {
       _except(ctx, E_STK, "Misaligned stack REGS");
    }

    if (ctx->r[RSP].val > ctx->r[RBP].val) {
        _except(ctx, E_STK, "RSP above RBP");
    }

    writemem64(ctx, ctx->r[RIP].val, ctx->r[RSP].val);
    ctx->r[RSP].val -= 8;
    ctx->r[RIP].val = v1;
}
IMPL_END;

IMPL_START_0(ret)
{
    if (ctx->r[RSP].val % 8 > 0 || ctx->r[RBP].val % 8 > 0) {
       _except(ctx, E_STK, "Misaligned stack REGS");
    }

    if (ctx->r[RSP].val >= ctx->r[RBP].val) {
        _except(ctx, E_STK, "RBP above RSP");
    }

    ctx->r[RSP].val += 8;
    ctx->r[RIP].val = readmem64(ctx, ctx->r[RSP].val);
}
IMPL_END;

IMPL_START_0(pushf)
{
    if (ctx->r[RSP].val % 8 > 0 || ctx->r[RBP].val % 8 > 0) {
       _except(ctx, E_STK, "Misaligned stack REGS");
    }

    if (ctx->r[RSP].val > ctx->r[RBP].val) {
        _except(ctx, E_STK, "RSP above RBP");
    }

    writemem64(ctx, ctx->r[FLG].val, ctx->r[RSP].val);
    ctx->r[RSP].val -= 8;
}
IMPL_END;

IMPL_START_0(popf)
{
    if (ctx->r[RSP].val % 8 > 0 || ctx->r[RBP].val % 8 > 0) {
       _except(ctx, E_STK, "Misaligned stack REGS");
    }

    if (ctx->r[RSP].val >= ctx->r[RBP].val) {
        _except(ctx, E_STK, "RBP above RSP");
    }
    
    CHK_SUPERV(); // XXX

    ctx->r[RSP].val += 8;
    ctx->r[FLG].val = readmem64(ctx, ctx->r[RSP].val);
}
IMPL_END;

//
// Supervisor only instructions
//

IMPL_START_0(cli)
{
    CHK_SUPERV();
    ctx->r[FLG].val &= ~IF;
}
IMPL_END;

IMPL_START_0(sti)
{
    CHK_SUPERV();
    ctx->r[FLG].val |= IF;
}
IMPL_END;

IMPL_START_0(stop)
{
    _except(ctx, E_SHT, "STOP INSTR");
}
IMPL_END;