53 lines
1.2 KiB
NASM
53 lines
1.2 KiB
NASM
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; Arguments:
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; [Furthest from EBP]
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; 1. U32 Stepping
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; 0. U32 Affected Value
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; [Nearest to EBP]
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;
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; Returns:
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; - EAX: The next higher multiple of the stepping,
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; as calculated from affected value.
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ceil_to:
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.prolog:
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push esi
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sub esp, 16
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mov esi, esp
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mov [esi + (16 - 4)], ecx
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mov [esi + (16 - 8)], edx
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.check_values:
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mov eax, [ebp - 4]
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cmp eax, 0
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jne .affected_value_is_valid
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xor eax, eax
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jmp .epilog
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.affected_value_is_valid:
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mov ecx, [ebp - 8]
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cmp ecx, 0
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jne .calculate
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xor eax, eax
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jmp .epilog
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.calculate:
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; Calculate how much needs ot be added to the
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; affected value for it to become a multiple of
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; the stepping using the remainder part of the division.
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div ecx
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; EDX now contains how much the affected value
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; 'goes over' the last multiple of the stepping.
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; Now, it can be calculated how much has to be added
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; to the affected value to make it the next multiple
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; of the stepping.
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mov ecx, [ebp - 8]
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sub ecx, edx
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mov eax, [ebp - 4]
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add eax, ecx
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.epilog:
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mov edx, [esi + (16 - 8)]
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mov ecx, [esi + (16 - 4)]
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add esp, 16
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pop esi
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ret
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