source: mainline/uspace/lib/c/generic/context.c@ a35a3d8

/*
 * Copyright (c) 2018 CZ.NIC, z.s.p.o.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <context.h>
#include <setjmp.h>
#include <libarch/tls.h>
#include <libarch/fibril.h>
#include <libarch/faddr.h>

/**
 * Saves current context to the variable pointed to by `self`,
 * and restores the context denoted by `other`.
 *
 * When the `self` context is later restored by another call to
 * `context_swap()`, the control flow behaves as if the earlier call to
 * `context_swap()` just returned.
 */
void context_swap(context_t *self, context_t *other)
{
        if (!__setjmp(self))
                __longjmp(other, 1);
}

void context_create(context_t *context, const context_create_t *arg)
{
        __setjmp(context);
        context_set(context, FADDR(arg->fn), arg->stack_base,
            arg->stack_size, arg->tls);
}

uintptr_t context_get_pc(context_t *ctx)
{
        // This is a simple wrapper for now, and exists to allow
        // potential future implementation of context_swap to omit
        // program counter from the context structure (e.g. if it's
        // stored on the stack).
        return ctx->pc;
}

uintptr_t context_get_fp(context_t *ctx)
{
        return _context_get_fp(ctx);
}