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