75 lines
2.2 KiB
Plaintext
75 lines
2.2 KiB
Plaintext
## Copyright (C) 2021 Andrius Štikonas
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## Copyright (C) 2023 Janneke Nieuwenhuizen <janneke@gnu.org>
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##
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## This file is part of stage0.
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##
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## stage0 is free software: you can redistribute it and/or modify
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## it 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
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## (at your option) any later version.
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##
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## stage0 is distributed in the hope that it will be useful,
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## but 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 stage0. If not, see <http://www.gnu.org/licenses/>.
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:_start
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RD_FP RS1_SP MV ; Protect stack pointer
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; Prepare argv
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RD_A0 RS1_FP !8 ADDI ; ARGV_address = FP + 8
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RD_SP RS1_SP !-8 ADDI
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RS1_SP RS2_A0 SD ; Put argv on the stack
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; Prepare envp
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RD_A0 RS1_FP MV ; Address we need to load from
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RD_A0 RS1_A0 LD ; Get ARGC
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RD_A0 RS1_A0 !2 ADDI ; OFFSET = ARGC + 2
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RD_A0 RS1_A0 RS2_X3 SLLI ; OFFSET = OFFSET * WORDSIZE
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RD_A0 RS1_FP RS2_A0 ADD ; ENVP_address = RSP + OFFSET
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RD_SP RS1_SP !-8 ADDI
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RS1_SP RS2_A0 SD ; Put envp on the stack
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# AAARG, this also does not work!?
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# pop____%t0 ; envp
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# push___%t0
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# li_____%t0,$i32 &GLOBAL_environ
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# li_____%t0,$i16_0000 @0
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# XXX avoid Illegal instruction
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# li_____%t1,$i32 &GLOBAL___stdin
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# sw_____%t0,0(%t1)
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# li_____%t0,$i16_0000 @1
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# srai___%t0,16
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# li_____%t1,$i32 &GLOBAL___stdout
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# sw_____%t0,0(%t1)
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# li_____%t0,$i16_0000 @2
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# XXX avoid Segmentation fault
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# srai___%t0,16
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# li_____%t1,$i32 &GLOBAL___stderr
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# sw_____%t0,0(%t1)
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; Stack offset
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RD_FP RS1_FP !8 ADDI
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; Init libc
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RD_RA $FUNCTION___init_io JAL
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; Call main function
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RD_RA $FUNCTION_main JAL
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; Put return value on the stack so that _exit gets it
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RD_SP RS1_SP !-16 ADDI
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RS1_SP RS2_A0 SD
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; Exit to kernel
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RD_A0 RS1_SP LD
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RD_A7 !93 ADDI ; Syscall for exit
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ECALL ; Exit with code in a0
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