92 lines
2.1 KiB
ArmAsm
92 lines
2.1 KiB
ArmAsm
; Copyright (C) 2016 Jeremiah Orians
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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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;; Readline function
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;; Receives Pointer to node in R0
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;; And Input in R1
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;; Allocates Text segment on Heap
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;; Sets node's pointer to Text segment
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;; Sets R14 to True if EOF reached
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;; Requires a malloc function to exist
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;; Returns to whatever called it
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:Readline
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;; Preserve registers
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PUSHR R0 R15
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PUSHR R1 R15
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PUSHR R2 R15
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PUSHR R3 R15
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PUSHR R4 R15
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;; Initialize
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MOVE R4 R0
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FALSE R0 ; Get where space is free
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CALLI R15 @malloc
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MOVE R2 R0
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FALSE R3
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:Readline_0
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FGETC ; Read a Char
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;; Flag if reached EOF
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CMPSKIPI.GE R0 0
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TRUE R14
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;; Stop if EOF
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CMPSKIPI.GE R0 0
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JUMP @Readline_2
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;; Handle Backspace
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CMPSKIPI.E R0 127
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JUMP @Readline_1
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;; Move back 1 character if R3 > 0
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CMPSKIPI.LE R3 0
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SUBUI R3 R3 1
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;; Hopefully they keep typing
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JUMP @Readline_0
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:Readline_1
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;; Replace all CR with LF
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CMPSKIPI.NE R0 13
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LOADUI R0 10
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;; Store the Byte
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STOREX8 R0 R2 R3
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;; Prep for next loop
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ADDUI R3 R3 1
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;; Check for EOL
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CMPSKIPI.NE R0 10
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JUMP @Readline_2
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;; Otherwise loop
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JUMP @Readline_0
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:Readline_2
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;; Set Text pointer
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CMPSKIPI.E R3 0 ; Don't bother for Empty strings
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STORE32 R2 R4 8
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;; Correct Malloc
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MOVE R0 R3 ; Ensure actually allocates exactly
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CALLI R15 @malloc ; the amount of space required
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;; Restore Registers
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POPR R4 R15
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POPR R3 R15
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POPR R2 R15
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POPR R1 R15
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POPR R0 R15
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RET R15
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