// 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 <pc/device.h>

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

#define MAX_RFRAME_IDX 255

//
// Register frames
//
ulong **rfs = NULL;

size_t rfs_used = 0;
size_t rfs_current_idx = 0;

#define CHK_INDEX(idx)                                                       \
    if ((size_t)idx > MAX_RFRAME_IDX)                                        \
        _except(E_UDF, "cpudev: invalid rframe index: #%u", idx);

#define CHK_FRAME(idx)                                                      \
    CHK_INDEX(idx);                                                         \
    if (rfs[idx] == NULL)                                                   \
        _except(E_UDF,                                                      \
            "cpudev: operation on inactive reframe #%u", idx);

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

long cpudev_getmaxidx(dev_t *dev)
{
    R(RAX) = MAX_RFRAME_IDX;
    return 0;
}

long cpudev_getrfusage(dev_t *dev)
{
    R(RAX) = rfs_used;
    return 0;
}

long cpudev_getcuridx(dev_t *dev)
{
    R(RAX) = rfs_current_idx;
    return 0;
}

long cpudev_leastavail(dev_t *dev)
{
    size_t it;

    for (it = 0; it <= MAX_RFRAME_IDX; it++)
    {
        if (rfs[it] == NULL)
        {
            R(RAX) = it;
            return 0;
        }
    }

    R(RAX) = -1;
    return 0;
}

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

long cpudev_isactive(dev_t *dev)
{
    CHK_INDEX(R(AX0));

    R(RAX) = (rfs[R(AX0)] != NULL);

    return 0;
}

long cpudev_activate(dev_t *dev)
{
    CHK_INDEX(R(AX0));
    
    if (rfs[R(AX0)] != NULL)
        _except(E_UDF,
            "cpudev: activating already activated rframe: #%u", R(AX0));

    rfs[R(AX0)] = calloc(NREGS, sizeof(ulong));

    if (rfs[R(AX0)] == 0)
        return -1;

    rfs_used++;

    return 0;
}

long cpudev_deactivate(dev_t *dev)
{
    CHK_FRAME(R(AX0));
    
    if (R(AX0) == 0)
        _except(E_UDF, "cpudev: deactivating rframe #0");

    free(rfs[R(AX0)]);
    rfs[R(AX0)] = NULL;

    rfs_used--;
    assert(rfs_used > 0);

    return 0;
}

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

long cpudev_copyframe(dev_t *dev)
{
    CHK_FRAME(R(AX0));
    CHK_FRAME(R(AX1));

    if (R(AX0) == R(AX1))
        return -1;

    memcpy(rfs[R(AX0)], rfs[R(AX1)], NREGS * sizeof(ulong));

    return 0;
}

long cpudev_moveframe(dev_t *dev)
{
    CHK_INDEX(R(AX0));
    CHK_FRAME(R(AX1));

    if (R(AX1) == 0)
        _except(E_UDF, "cpudev: trying to move frame #0");

    if (rfs[R(AX0)] != NULL)
        _except(E_UDF, "cpudev: trying to move frame #%u "
                            "active frame #%u", R(AX1), R(AX0));

    rfs[R(AX0)] = rfs[R(AX1)];
    rfs[R(AX1)] = NULL;

    return 0;
}

long cpudev_switchframe(dev_t *dev)
{
    CHK_FRAME(R(AX0));

    rfs_current_idx = R(AX0);
    ctx->rf = rfs[R(AX0)];

    return 0;
}

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

long cpudev_loadargs(dev_t *dev)
{
    CHK_FRAME(R(AX0));

    R(AX5) = rfs[R(AX0)][AX5];
    R(AX4) = rfs[R(AX0)][AX4];
    R(AX3) = rfs[R(AX0)][AX3];
    R(AX2) = rfs[R(AX0)][AX2];
    R(AX1) = rfs[R(AX0)][AX1];
    R(AX0) = rfs[R(AX0)][AX0];

    return 0;
    
}
long cpudev_loadreg(dev_t *dev)
{
    CHK_FRAME(R(AX0));

    if ((ushort)R(AX1) >= NREGS || R(AX1) == RZX)
        _except(E_UDF,
            "cpudev: register invalid or index out of range: #%u", R(AX1));

    R(RAX) = rfs[R(AX0)][R(AX1)];

    return 0;
}

long cpudev_storereg(dev_t *dev)
{
    CHK_FRAME(R(AX0));

    if ((ushort)R(AX1) >= NREGS)
        _except(E_UDF, "cpudev: register index out of range: #%u", R(AX1));

    rfs[R(AX0)][R(AX1)] = R(AX2);

    return 0;
}

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

#define CHK_IDT_INDEX(idx)                                                  \
    if ((ulong)idx >= IDT_SLOTS)                                            \
        _except(E_UDF, "cpudev: invalid IDT slot index: #%u", idx);

/* except.h */
ulong idt[IDT_SLOTS] = { 0 };
bool idt_masked[IDT_SLOTS] = { 0 };         // deliberately masked by software
bool idt_handling[IDT_SLOTS] = { 0 };       // a handler is already running

long cpudev_idtadd(dev_t *dev)
{
    CHK_FRAME(R(AX1));
    CHK_IDT_INDEX(R(AX0));

    if (idt[R(AX0)] != 0)
        _except(E_UDF, "cpudev: IDT slot index already in use: #%u", R(AX0));

    assert(idt_handling[R(AX0)] == 0);

    idt[R(AX0)] = R(AX1);

    return 0;
}

long cpudev_idtdel(dev_t *dev)
{
    CHK_IDT_INDEX(R(AX0));

    if (idt[R(AX0)] == 0)
        _except(E_UDF, "cpudev: IDT slot index not in use: #%u", R(AX0));

    idt[R(AX0)] = 0;
    idt_handling[R(AX0)] = 0;

    return 0;
}

long cpudev_idtquery(dev_t *dev)
{
    if (R(AX0) >= IDT_SLOTS || idt[R(AX0)] == 0)
        R(RAX) = R(RDX) = 0;

    else {
        R(RAX) = 1;
        R(RDX) = idt[R(AX0)];
    }

    return 0;
}

long cpudev_idtdone(dev_t *dev)
{
    CHK_IDT_INDEX(R(AX0));

    if (idt_handling[R(AX0)] == 0)
        _except(E_UDF, "cpudev: idtdone, not handling E/I #%u", R(AX0));

    idt_handling[R(AX0)]--;

    return 0;
}

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

long cpudev_poweron(dev_t *dev)
{
    rfs = calloc(MAX_RFRAME_IDX + 2, sizeof(reg_t *));
    
    if (rfs == NULL)
        return -1;

    rfs[0] = ctx->rf;
    rfs_used = 1;

    dev->state = DEVGOOD;
    
    dev->fslots[16] = cpudev_getmaxidx;
    dev->fslots[17] = cpudev_getrfusage;
    dev->fslots[18] = cpudev_getcuridx;
    dev->fslots[19] = cpudev_leastavail;
    dev->fslots[20] = cpudev_isactive;
    dev->fslots[21] = cpudev_activate;
    dev->fslots[22] = cpudev_deactivate;
    dev->fslots[23] = cpudev_copyframe;
    dev->fslots[24] = cpudev_moveframe;
    dev->fslots[25] = cpudev_switchframe;

    dev->fslots[32] = cpudev_loadargs;
    dev->fslots[33] = cpudev_loadreg;
    dev->fslots[48] = cpudev_storereg;

    dev->fslots[64] = cpudev_idtadd;
    dev->fslots[65] = cpudev_idtdel;
    dev->fslots[66] = cpudev_idtquery;
    dev->fslots[67] = cpudev_idtdone;

    return 0;
}

long cpudev_poweroff(dev_t *dev)
{
    size_t i;

    if (rfs)
    {
        for (i = 0; i <= MAX_RFRAME_IDX; i++)
            free(rfs[i]);

        free(rfs);
    }

    dev->state = DEVPWOF;

    return 0;
}

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

dev_t cpudev =
{
    .type = "cpu",
    .name = "K-CPU",
    .modl = "Prisma 1",
    .vend = "The OS/K Team",

    .major = KARCH_MAJOR,
    .minor = KARCH_MINOR,
    .revis = KARCH_REVIS,

    .fpwon = cpudev_poweron,
    .fpwoff = cpudev_poweroff,
};