/*
 * nanowasm, a tiny WebAssembly/Wasm interpreter
 * Copyright (C) 2023-2025  Xavier Del Campo Romero
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include <nanowasm/nw.h>
#include <nw/io.h>
#include <nw/ops.h>

static enum nw_state loop(struct nw_mod *m);

static enum nw_state get_default_target(struct nw_mod *const m)
{
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_c *const c = &m->sm.code;
    struct nw_sm_leb128 *const l = &c->leb128;
    nw_varuint32 target;
    const enum nw_state n = nwp_varuint32(cfg, l, &target, cfg->user);

    if (n)
        return n;

    m->next = c->next;
    return NW_AGAIN;
}

static enum nw_state get_entry(struct nw_mod *const m)
{
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_c *const c = &m->sm.code;
    struct nw_sm_c_t *const t = &c->u.target;
    struct nw_sm_leb128 *const l = &c->leb128;
    nw_varuint32 entry;
    const enum nw_state n = nwp_varuint32(cfg, l, &entry, cfg->user);

    if (n)
        return n;

    t->i++;
    m->next = loop;
    return NW_AGAIN;
}

static enum nw_state loop(struct nw_mod *const m)
{
    const struct nw_sm_c *const c = &m->sm.code;
    const struct nw_sm_c_t *const t = &c->u.target;

    m->next = t->i >= t->count ? get_default_target : get_entry;
    return NW_AGAIN;
}

static enum nw_state get_target_count(struct nw_mod *const m)
{
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_c *const c = &m->sm.code;
    struct nw_sm_leb128 *const l = &c->leb128;
    struct nw_sm_c_t *const t = &c->u.target;
    const enum nw_state n = nwp_varuint32(cfg, l, &t->count, cfg->user);

    if (n)
        return n;

    m->next = loop;
    return NW_AGAIN;
}

void nwp_op_check_br_table(struct nw_mod *const m)
{
    static const struct nw_sm_c_t t;

    m->sm.code.u.target = t;
    m->next = get_target_count;
}