// 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/arch.h>

#ifdef _NEED_DISASM
#define _except __except

static inline void _except(ctx_t *ctx, int x, char *fmt, ...)
{
    va_list ap;

    log("Disassembly error: ");

    va_start(ap, fmt);
    vlog(fmt, ap);
    va_end(ap);

    log("\n");

    if (ctx->disf)
        fclose(ctx->disf);

    exit(-1);
}

#endif

static void scan_param(ctx_t *ctx, acc_t *p)
{
    ushort c;
    reg_t *r;

    c = ctx->get(ctx);

    if (A_IS_MEM(c)) {
        p->mem = 1;
        p->off = 0;
        p->mlen = c & 0xF;
        c = ctx->get(ctx);
    }

    else if (A_IS_OFF(c)) {
        p->mem = 1;
        p->mlen = c & 0xF;
        p->off = (short)ctx->get(ctx);

        p->offreg = ctx->get(ctx);

        if (p->offreg > NREGS) {
            _except(ctx, E_ILL, "Inexistent REG (offreg)");
        }

        if (p->offreg != INV) {
            r = &ctx->r[p->offreg];

            if (r->flags & (RES | CTL)) {
                _except(ctx, E_ACC, "Reserved REG (offreg): %s", r->name);
            }
        }

        c = ctx->get(ctx);
    }

    if (c >= A_IMM16) {
        // Check for double access code
        if (p->type != A_REG)
            _except(ctx, E_ILL, "Bad access code");

        p->type = c;
        c = ctx->get(ctx);
    }

    p->val = c;

    if (p->type == A_IMM32) {
        p->ilen = 4;
        p->val = p->val | ((ulong)ctx->get(ctx) << 16);
    }

    else if (p->type == A_IMM64) {
        p->ilen = 8;
        p->val = p->val | ((ulong)ctx->get(ctx) << 16);
        p->val = p->val | ((ulong)ctx->get(ctx) << 32);
        p->val = p->val | ((ulong)ctx->get(ctx) << 48);
    }

    else if (p->type == A_REG) {
        if (p->val > NREGS) {
            _except(ctx, E_ILL, "Inexistent REG");
        }

        r = &ctx->r[p->val];

        if (r->flags & (RES | CTL)) {
            _except(ctx, E_ACC, "Reserved REG: %s", r->name);
        }
    }
}

#ifndef _NEED_DISASM
void decode(ctx_t *ctx)
#else
void disasm(ctx_t *ctx)
#endif
{
    instr_t *i;
    acc_t p1 = { 0 }, p2 = { 0 };

    uint rep = 0;
    ulong orig_rip = rip;
    ushort c = ctx->get(ctx);

    if (ISPREF(c)) {
        if (c == PREF_REP) {
            rep = 1;
            c = ctx->get(ctx);
        }
    }

    else if (!ISINSTR(c)) {
        _except(ctx, E_ILL, "Bad opcode: 0x%04hX", c);
    }

    i = &ctx->i[c];

    // Scan for parameters
    if (i->prm1 != NOPRM) {
        scan_param(ctx, &p1);
        if (i->prm2 != NOPRM) {
            scan_param(ctx, &p2);
        }
    }

#ifdef _NEED_DISASM
    dumpinstr(ctx, orig_rip, rep, c, &p1, &p2);
#else

do_rep:
    dumpinstr(ctx, orig_rip, rep, c, &p1, &p2);
    i->func(ctx, &p1, &p2);


    if (rep && rcx > 0) {
        rcx--;
        goto do_rep;
    }

#endif
}