60 lines
1.6 KiB
ArmAsm
60 lines
1.6 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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;; add_node Function
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;; Recieves pointers in R0 R1
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;; Alters R0 if NULL
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;; Appends nodes together
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;; Returns to whatever called it
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:add_node
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;; Preserve Registers
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PUSHR R2 R15
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PUSHR R1 R15
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PUSHR R0 R15
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;; Handle if Head is NULL
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JUMP.NZ R0 @add_node_0
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POPR R0 R15
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PUSHR R1 R15
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JUMP @add_node_2
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:add_node_0
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;; Handle if Head->next is NULL
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LOAD32 R2 R0 0
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JUMP.NZ R2 @add_node_1
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;; Set head->next = p
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STORE32 R1 R0 0
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;; Set p->prev = head
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STORE32 R0 R1 4
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JUMP @add_node_2
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:add_node_1
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;; Handle case of Head->next not being NULL
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LOAD32 R0 R0 0 ; Move to next node
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LOAD32 R2 R0 0 ; Get node->next
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CMPSKIPI.E R2 0 ; If it is not null
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JUMP @add_node_1 ; Move to the next node and try again
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JUMP @add_node_0 ; Else simply act as if we got this node
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; in the first place
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:add_node_2
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;; Restore registers
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POPR R0 R15
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POPR R1 R15
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POPR R2 R15
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RET R15
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