54 lines
1.5 KiB
ArmAsm
54 lines
1.5 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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# We will be using R0 request a number of bytes
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# The pointer to the block of that size is to be
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# passed back in R0, for simplicity sake
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# R15 will be used as the stack pointer
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:start
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LOADUI R15 @stack
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LOADUI R0 22 ; Allocate 22 bytes
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CALLI R15 @malloc
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LOADUI R0 42 ; Allocate 42 bytes
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CALLI R15 @malloc
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HALT
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;; Our simple malloc function
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:malloc
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;; Preserve registers
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PUSHR R1 R15
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;; Get current malloc pointer
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LOADR R1 @malloc_pointer
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;; Deal with special case
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CMPSKIPI.NE R1 0 ; If Zero set to our start of heap space
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LOADUI R1 0x600
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;; update malloc pointer
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SWAP R0 R1
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ADD R1 R0 R1
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STORER R1 @malloc_pointer
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;; Done
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;; Restore registers
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POPR R1 R15
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RET R15
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;; Our static value for malloc pointer
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:malloc_pointer
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NOP
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;; Start stack at end of instructions
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:stack
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