71 lines
2.1 KiB
C
71 lines
2.1 KiB
C
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/* -*-comment-start: "//";comment-end:""-*-
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* GNU Mes --- Maxwell Equations of Software
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* Copyright © 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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* Copyright © 2021 W. J. van der Laan <laanwj@protonmail.com>
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*
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* This file is part of GNU Mes.
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*
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* GNU Mes is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* GNU Mes is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "mes/lib-mini.h"
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int main (int argc, char *argv[], char *envp[]);
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/* mesc will generate the following preamble:
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push ra
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push fp
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*/
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int
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_start ()
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{
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asm ("li_____%t0,$i16_0000 @0");
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asm ("li_____%t1,$i32 &__stdin");
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asm ("sw_____%t0,0(%t1)");
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asm ("li_____%t0,$i16_0000 @1");
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asm ("srai___%t0,16");
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asm ("li_____%t1,$i32 &__stdout");
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asm ("sw_____%t0,0(%t1)");
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asm ("li_____%t0,$i16_0000 @2");
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asm ("srai___%t0,16");
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asm ("li_____%t1,$i32 &__stderr");
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asm ("sw_____%t0,0(%t1)");
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// environ is &argv[argc + 1]
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asm ("mv_____%t1,%fp");
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asm ("addi___%t1,%t1,$i8_8 !0x1"); // 0x10 to skip over pushed fp+ra, 0x8 to skip over argc
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asm ("addi___%t5,%fp,$i8_0 !0x1"); // 0x10 to skip over pushed fp+ra
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asm ("ld_____%t0,0(%t5)");
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asm ("addi___%t0,%t0,1");
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asm ("li_____%t5,$i32 %0x3"); // skip over all arguments and the final NULL
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asm ("sll____%t0,%t0,%t5");
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asm ("add____%t0,%t0,%t1");
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asm ("push___%t0"); // envp
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asm ("push___%t1"); // argv
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asm ("li_____%t1,$i32 &environ");
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asm ("sd_____%t0,0(%t1)");
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asm ("addi___%t5,%fp,$i8_0 !0x1"); // 0x10 to skip over pushed fp+ra
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asm ("ld_____%t0,0(%t5)");
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asm ("push___%t0"); // argc
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main ();
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asm ("mv_____%a0,%t0");
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asm ("li_____%a7,SYS_exit");
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asm ("ecall");
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asm ("ebreak");
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}
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