mes/lib/linux/riscv64-mes-mescc/crt1.c

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/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2018,2023 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
* Copyright © 2021 W. J. van der Laan <laanwj@protonmail.com>
*
* This file is part of GNU Mes.
*
* GNU Mes is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* GNU Mes is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mes/lib-mini.h"
int main (int argc, char *argv[], char *envp[]);
/* mesc will generate the following preamble:
push ra
push fp
*/
int
_start ()
{
// environ is &argv[argc + 1]
asm ("mv_____%t1,%fp");
asm ("addi___%t1,%t1,$i8_8 !0x1"); // 0x10 to skip over pushed fp+ra, 0x8 to skip over argc
asm ("addi___%t5,%fp,$i8_0 !0x1"); // 0x10 to skip over pushed fp+ra
asm ("ld_____%t0,0(%t5)");
asm ("addi___%t0,%t0,1");
asm ("li_____%t5,$i32 %0x3"); // skip over all arguments and the final NULL
asm ("sll____%t0,%t0,%t5");
asm ("add____%t0,%t0,%t1");
asm ("push___%t0"); // envp
asm ("push___%t1"); // argv
asm ("sd_____%t0,0(%t1)");
asm ("addi___%t5,%fp,$i8_0 !0x1"); // 0x10 to skip over pushed fp+ra
asm ("ld_____%t0,0(%t5)");
asm ("push___%t0"); // argc
__init_io ();
main ();
asm ("mv_____%a0,%t0");
asm ("li_____%a7,SYS_exit");
asm ("ecall");
asm ("ebreak");
}