stage0/Library function prototypes/malloc.s

54 lines
1.5 KiB
ArmAsm

; Copyright (C) 2016 Jeremiah Orians
; This file is part of stage0.
;
; stage0 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.
;
; stage0 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 stage0. If not, see <http://www.gnu.org/licenses/>.
# We will be using R0 request a number of bytes
# The pointer to the block of that size is to be
# passed back in R0, for simplicity sake
# R15 will be used as the stack pointer
:start
LOADUI R15 @stack
LOADUI R0 22 ; Allocate 22 bytes
CALLI R15 @malloc
LOADUI R0 42 ; Allocate 42 bytes
CALLI R15 @malloc
HALT
;; Our simple malloc function
:malloc
;; Preserve registers
PUSHR R1 R15
;; Get current malloc pointer
LOADR R1 @malloc_pointer
;; Deal with special case
CMPSKIPI.NE R1 0 ; If Zero set to our start of heap space
LOADUI R1 0x600
;; update malloc pointer
SWAP R0 R1
ADD R1 R0 R1
STORER R1 @malloc_pointer
;; Done
;; Restore registers
POPR R1 R15
RET R15
;; Our static value for malloc pointer
:malloc_pointer
NOP
;; Start stack at end of instructions
:stack