Rain dog:
Actually, multiplication is made in constant time. I don't remember the exact mechanics that the ALU units use at the moment (it's been 7 years since I took the course in computer architecture), but I can assure you that it's not a series of adds. I believe MUL is only 1 clock cycle on the x86 processors.
Division, however, is not constant time, as it is repeated until enough precision has been reached. The more precision you need the longer it takes.
If I were to implement a power-of operator, I think I would indeed go with x pow y, as it is easier to remember than x ** y. I already have a few operators like that (and, or, and xor) so it won't be difficult to implement.
Fruny:
You actually gave me the idea to allow the applications to dynamically register operators. It would then be possible to register operators like 'pow', 'cat', and 'mod', as needed. It is an interesting idea, but I don't think I'll implement it, I'm already trying to simplify the library. [wink]
[Edited by - WitchLord on April 10, 2005 10:08:50 AM]
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Exponent Operator
Author
Usage: MUL src Modifies flags: CF OF (AF,PF,SF,ZF undefined) Unsigned multiply of the accumulator by the source. If "src" is a byte value, then AL is used as the other multiplicand and the result is placed in AX. If "src" is a word value, then AX is multiplied by "src" and DX:AX receives the result. If "src" is a double word value, then EAX is multiplied by "src" and EDX:EAX receives the result. The 386+ uses an early out algorithm which makes multiplying any size value in EAX as fast as in the 8 or 16 bit registers. Clocks Size Operands 808x 286 386 486 Bytes reg8 70-77 13 9-14 13-18 2 reg16 118-113 21 9-22 13-26 2 reg32 - - 9-38 13-42 2-4 mem8 (76-83)+EA 16 12-17 13-18 2-4 mem16 (124-139)+EA 24 12-25 13-26 2-4 mem32 - - 12-21 13-42 2-4 F6 /4 MUL r/m8 Unsigned multiply (AX ¬ AL * r/m8) F7 /4 MUL r/m16 Unsigned multiply (DX:AX ¬ AX * r/m16) F7 /4 MUL r/m32 Unsigned multiply (EDX:EAX ¬ EAX * r/m32)That is taken from the MASM32 OPCODE help file.
Compared with ADD,
ADD - Arithmetic Addition Usage: ADD dest,src Modifies flags: AF CF OF PF SF ZF Adds "src" to "dest" and replacing the original contents of "dest". Both operands are binary. Clocks Size Operands 808x 286 386 486 Bytes reg,reg 3 2 2 1 2 mem,reg 16+EA 7 7 3 2-4 (W88=24+EA) reg,mem 9+EA 7 6 2 2-4 (W88=13+EA) reg,immed 4 3 2 1 3-4 mem,immed 17+EA 7 7 3 3-6 (W88=23+EA) accum,immed 4 3 2 1 2-3It does appear that MUL is varying in clock cycles.
[Edited by - Rain Dog on April 9, 2005 4:14:27 PM]
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