/*      $OpenBSD: sbrk.S,v 1.4 2022/12/03 15:02:30 jca Exp $    */
/*
 * Copyright (c) 2021 Dale Rahn <drahn@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "SYS.h"

        .extern _end

        .data
        .align  3
        .globl  __curbrk
        .hidden __curbrk
        .type   __curbrk,@object
__curbrk:
        .dword _end
        END(__curbrk)
        
ENTRY_NB(sbrk)
        RETGUARD_SETUP(sbrk, t6)

        lla     t1, __curbrk
        ld      a2, 0(t1)
        add     a0, a0, a2      // compute current break
        mv      t3, a0
        SYSTRAP(break)
        beqz    t0, .L_sbrk_ok
        sw      a0, TP_OFFSET_ERRNO(tp)
        li      a0, -1
        j       .L_sbrk_fail
.L_sbrk_ok:
        sd      t3, 0(t1)       // save current val of curbrk from above
        mv      a0, a2          // return old val of curbrk from above
.L_sbrk_fail:
        RETGUARD_CHECK(sbrk, t6);
        ret
END(sbrk)
        .weak   sbrk