56 lines
977 B
NASM
56 lines
977 B
NASM
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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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call kprintf
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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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; out si 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, FF = in use
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malloc:
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push ax
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mov si,heap
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jmp .check
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.next:
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mov si,[si]
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.check:
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mov ax,[si]
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test ax,0xFFFF
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jz .append ; we are on last entry
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cmp byte [si+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
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.reuse: ; exact length
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mov byte [si+2],0xFF
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add si, 0x03
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pop ax
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ret
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.append: ; append to last item
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mov ax, si
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add ax, 3
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add ax, cx
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mov word [si], ax
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mov byte [si+2], 0xFF
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push si
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mov word si,[si]
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mov byte [si],0x0000
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pop si
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add si, 0x03
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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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