54 lines
1.7 KiB
Plaintext
54 lines
1.7 KiB
Plaintext
## Copyright (C) 2021 Andrius Štikonas
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## Copyright (C) 2023 Janneke Nieuwenhuizen <janneke@gnu.org>
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## Copyright © 2023 Andrius Štikonas <andrius@stikonas.eu>
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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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; 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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