59 lines
1.1 KiB
NASM
59 lines
1.1 KiB
NASM
verbose_malloc:
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call malloc
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push si ; both backup and input value for kprintf
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mov si,.fmt
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push di
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call kprintf
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pop di
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pop si
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ret
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.fmt:
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db "malloc %X", 0
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; Allocates memory on the kernel heap
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; Strategy: smallest fit
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; in cx size in bytes
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; dl node type
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; out ds:di pointer
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;
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; Header:
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; word ptr to next item (this implies its size)
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; byte 00 = free, >0 used (refcount)
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; byte high-level type
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malloc:
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push ax
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push bx
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mov di,heap
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add cx, 0x04 ; header length
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jmp .check
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.next:
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add di,[di]
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.check:
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mov ax,[di]
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test ax,0xFFFF
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jz .append ; we are on last entry
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cmp byte [di+2],0x00
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jne .next ; entry is in use
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sub ax,cx
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je .reuse ; entry has exact length
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jc .next ; entry too short
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jmp .next ; we'd have to split, not implemented yet
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.reuse: ; exact length
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mov byte [di+2],0xFF
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jmp .end
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.append: ; append to last item
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mov word [di], cx
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mov byte [di+2], 0x00
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mov byte [di+3], dl
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push di
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add word di, [di]
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mov byte [di],0x0000
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pop di
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.end:
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pop bx
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pop ax
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ret
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; Deallocates memory on the kernel heap
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free:
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