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DimonSoft 10 Mar 2018, 19:06
CandyMan wrote: how to check whether the quotient will fit in AL before integer division (TheWord>0xFF)? You’d better perform division for double-sized values. Code: mov ax, [TheWord] cwd movsx cx, cl idiv cx You’re not in control of #DE anyway and wouldn’t like to be. So just prevent it. |
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10 Mar 2018, 19:06 |
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CandyMan 10 Mar 2018, 20:39
Thanks. This works with byte integer division. How to prevent exception in this case:
Code: mov edx,[Hi] mov eax,[Lo] idiv ecx _________________ smaller is better |
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10 Mar 2018, 20:39 |
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Tomasz Grysztar 10 Mar 2018, 21:38
You may already be aware that for unsigned division this is very simple:
Code: mov edx,[Hi] mov eax,[Lo] cmp edx,ecx jae overflow div ecx The signed case is much more complex. You need EDX:EAX to be larger than -(1 shl 31 + 1)*ECX and smaller than (1 shl 31)*ECX, this could be tested with some shifts, but would not be as nice and simple. |
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10 Mar 2018, 21:38 |
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CandyMan 11 Mar 2018, 12:33
I am thanking everyone for help.
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11 Mar 2018, 12:33 |
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