mes/lib/linux/arm-mes-m2/crt1.M1

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### GNU Mes --- Maxwell Equations of Software
### Copyright (C) 2016 Jeremiah Orians
### Copyright © 2022,2023 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
###
### 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/>.
:_start
'0' SP BP NO_SHIFT MOVE_ALWAYS ; Setup Base Pointer
;; Prepare argv
!4 R0 ADD BP ARITH_ALWAYS ; ARGV_address = BP + 4
{R0} PUSH_ALWAYS ; Put argv on the stack
;; Prepare envp
'0' BP R0 NO_SHIFT MOVE_ALWAYS ; Address we need to load from
!0 R0 LOAD32 R0 MEMORY ; Get ARGC
!2 R0 ADD R0 ARITH_ALWAYS ; OFFSET = ARGC + 2
'0' R0 R0 '1' MOVE_ALWAYS ; OFFSET = OFFSET * WORDSIZE
'0' R0 R0 ADD BP ARITH2_ALWAYS ; ENVP_address = BP + OFFSET
{R0} PUSH_ALWAYS ; Put envp on the stack
;; Stack offset
!4 BP ADD BP ARITH_ALWAYS ; Fix BP
^~FUNCTION___init_io CALL_ALWAYS ; Init libc
^~FUNCTION_main CALL_ALWAYS ; Jump right into main
SYS_exit mov____$i8,%r7
swi____$0
# Unsigned Divide
:divide
{R4} PUSH_ALWAYS ; Protect R4
{R3} PUSH_ALWAYS ; Protect R3
{R2} PUSH_ALWAYS ; Protect R2
'0' R0 R3 NO_SHIFT MOVE_ALWAYS ; MOV R3,R0
'0' R1 R2 NO_SHIFT MOVE_ALWAYS ; MOV R2,R1
!0 R0 LOADI8_ALWAYS ; MOV R0,#0
!0 CMPI8 R2 IMM_ALWAYS ; CMP R2,#0
!1 R0 SUB R0 ARITH_LT ; SUBLT R0,R0,#1
!0 CMPI8 R3 IMM_ALWAYS ; CMP R3,#0
!0 R3 RSUB R3 ARITH_LT ; RSBLT R3,R3,#0
'0' R0 R0 MVN_LT ; MVNLT R0,R0
'0' R0 R4 NO_SHIFT MOVE_ALWAYS ; MOV R4,R0
!32 R0 LOADI8_ALWAYS ; MOV R0,#32.
!0 R1 LOADI8_ALWAYS ; MOV R1,#0
:divide_loop
'0' R2 R2 ADDS R2 ARITH2_ALWAYS ; ADDS R2,R2,R2
'0' R1 R1 ADCS R1 ARITH2_ALWAYS ; ADCS R1,R1,R1
'0' R3 CMP R1 AUX_ALWAYS ; CMP R1,R3
'0' R3 R1 SUB R1 ARITH2_GE ; SUBGE R1,R1,R3
!1 R2 ADD R2 ARITH_GE ; ADDGE R2,R2,#1
!1 R0 SUB R0 ARITH_ALWAYS ; SUB R0,R0,#1
!0 CMPI8 R0 IMM_ALWAYS ; CMP R0,#0
^~divide_loop JUMP_NE ; BNE loop
'0' R2 R0 NO_SHIFT MOVE_ALWAYS ; MOV R0,R2
{R2} POP_ALWAYS ; Restore R2
{R3} POP_ALWAYS ; Restore R3
{R4} POP_ALWAYS ; Restore R4
'1' LR RETURN
# Signed Divide
:divides
{R4} PUSH_ALWAYS ; Protect R4
{R3} PUSH_ALWAYS ; Protect R3
{R2} PUSH_ALWAYS ; Protect R2
'0' R0 R3 NO_SHIFT MOVE_ALWAYS ; MOV R3,R0
'0' R1 R2 NO_SHIFT MOVE_ALWAYS ; MOV R2,R1
!0 R0 LOADI8_ALWAYS ; MOV R0,#0
!0 CMPI8 R2 IMM_ALWAYS ; CMP R2,#0
!0 R2 RSUB R2 ARITH_LT ; RSBLT R2,R2,#0
!1 R0 SUB R0 ARITH_LT ; SUBLT R0,R0,#1
!0 CMPI8 R3 IMM_ALWAYS ; CMP R3,#0
!0 R3 RSUB R3 ARITH_LT ; RSBLT R3,R3,#0
'0' R0 R0 MVN_LT ; MVNLT R0,R0
'0' R0 R4 NO_SHIFT MOVE_ALWAYS ; MOV R4,R0
!32 R0 LOADI8_ALWAYS ; MOV R0,#32.
!0 R1 LOADI8_ALWAYS ; MOV R1,#0
:divides_loop
'0' R2 R2 ADDS R2 ARITH2_ALWAYS ; ADDS R2,R2,R2
'0' R1 R1 ADCS R1 ARITH2_ALWAYS ; ADCS R1,R1,R1
'0' R3 CMP R1 AUX_ALWAYS ; CMP R1,R3
'0' R3 R1 SUB R1 ARITH2_GE ; SUBGE R1,R1,R3
!1 R2 ADD R2 ARITH_GE ; ADDGE R2,R2,#1
!1 R0 SUB R0 ARITH_ALWAYS ; SUB R0,R0,#1
!0 CMPI8 R0 IMM_ALWAYS ; CMP R0,#0
^~divides_loop JUMP_NE ; BNE loop
!0 CMPI8 R4 IMM_ALWAYS ; CMP R4,#0
!0 R2 RSUB R2 ARITH_NE ; RSBNE R2,R2,#0
'0' R2 R0 NO_SHIFT MOVE_ALWAYS ; MOV R0,R2
{R2} POP_ALWAYS ; Restore R2
{R3} POP_ALWAYS ; Restore R3
{R4} POP_ALWAYS ; Restore R4
'1' LR RETURN
# Unsigned Modulus
:modulus
{LR} PUSH_ALWAYS ; Prepare to leverage divide
^~divide CALL_ALWAYS ; Use divide
'0' R1 R0 NO_SHIFT MOVE_ALWAYS ; MOV R0,R1
{LR} POP_ALWAYS ; Prepare for return
'1' LR RETURN
# Signed Modulus
:moduluss
{LR} PUSH_ALWAYS ; Prepare to leverage divide
^~divides CALL_ALWAYS ; Use divides
'0' R1 R0 NO_SHIFT MOVE_ALWAYS ; MOV R0,R1
{LR} POP_ALWAYS ; Prepare for return
'1' LR RETURN