fox32os/kernel/allocator.asm
2022-05-19 14:15:40 -07:00

36 lines
636 B
NASM

; memory allocator routines
; this is a very basic memory allocator, it doesn't even allow freeing
; TODO: make this better
const MEMORY_TOP: 0x02000000
; allocate a block of memory
; inputs:
; r0: size in bytes
; outputs:
; r0: pointer to allocated block (or zero if no blocks free)
allocate_memory:
push r1
push r2
mov r1, MEMORY_TOP
mov r2, [free_base]
sub r1, r2
cmp r1, r0
iflteq jmp allocate_memory_full
mov r1, [free_base]
add [free_base], r0
mov r0, r1
pop r2
pop r1
ret
allocate_memory_full:
mov r0, 0
pop r2
pop r1
ret
free_base: data.32 kernel_bottom