Author: Uri Blass
Date: 22:54:57 07/06/03
Go up one level in this thread
On July 07, 2003 at 00:56:37, Reinhard Scharnagl wrote:
>On July 06, 2003 at 23:25:00, Uri Blass wrote:
>
>>In movei I have a number between 0 and 255 and I want to do some functions for
>>every 1 that it has in its binary representation(number of functions to
>>implement is the same as the number of 1's in the number and there is a
>>different function based on the value of the 1)
>>
>>I do not like to call functions because functions use local varaibles and
>>generating a copy of the local varaibles only to forget them may take computer
>>time and I also do not use the functions more than once.
>>
>>I thought to use switch(see the code later in this post) but the problem is that
>>switch continue to do everything without break and I want to have switch that
>>does not continue to do everything but does not quit and simply forget about the
>>fact that I called switch.
>>
>>Here is the type of the code that I plan to have now.
>>I do not like all the if (number&2) or if (number&4) and the question is if I
>>can do it faster.
>
>How about:
>
>_work:
>switch (number) {
>case [all numbers matching 0x01]:
> /* do list of 0-commands */;
> if ((number &= ~0x01) != 0) goto _work;
> break;
>case [all numbers left matching 0x02]:
> /* do list of 1-commands */;
> if ((number &= ~0x02) != 0) goto _work;
> break;
>case [all numbers left matching 0x04]:
> /* do list of 2-commands */;
> if ((number &= ~0x04) != 0) goto _work;
> break;
>case [all numbers left matching 0x08]:
> /* do list of 3-commands */;
> if ((number &= ~0x08) != 0) goto _work;
> break;
>case 0x10: case 0x30: case 0x50: case 0x70:
>case 0x90: case 0xB0: case 0xD0: case 0xF0:
> /* do list of 4-commands */;
> if ((number &= ~0x10) != 0) goto _work;
> break;
>case 0x20: case 0x60: case 0xA0: case 0xE0:
> /* do list of 5-commands */;
> if ((number &= ~0x20) != 0) goto _work;
> break;
>case 0x40: case 0xc0:
> /* do list of 6-commands */;
> if ((number &= ~0x40) == 0) break;
>case 0x80:
> /* do list of 7-commands */;
> break;
>}
>
>Or alternative by doubling code:
>
>_work:
>switch (number) {
>case 0x01:
> /* do list of 0-commands */;
> break;
>case [all numbers left matching 0x01 except 0x01]:
> /* do list of 0-commands */;
> number &= ~0x01; goto _work;
>
>case 0x02:
> /* do list of 1-commands */;
> break;
>case [all numbers left matching 0x02 except 0x02]:
> /* do list of 1-commands */;
> number &= ~0x02; goto _work;
>
>case 0x04:
> /* do list of 2-commands */;
> break;
>case [all numbers left matching 0x04 except 0x04]:
> /* do list of 2-commands */;
> number &= ~0x04; goto _work;
>
>case 0x08:
> /* do list of 3-commands */;
> break;
>case [all numbers left matching 0x08 except 0x08]:
> /* do list of 3-commands */;
> number &= ~0x08; goto _work;
>
>case 0x10:
> /* do list of 4-commands */;
> break;
>case 0x30: case 0x50: case 0x70:
>case 0x90: case 0xB0: case 0xD0: case 0xF0:
> /* do list of 4-commands */;
> number &= ~0x10; goto _work;
>
>case 0x20:
> /* do list of 5-commands */;
> break;
>case 0x60: case 0xA0: case 0xE0:
> /* do list of 5-commands */;
> number &= ~0x20; goto _work;
>
>case 0x40:
> /* do list of 6-commands */;
> break;
>case 0xc0:
> /* do list of 6-commands */;
>
>case 0x80:
> /* do list of 7-commands */;
> break;
>}
>
>Regards, Reinhard
I think that the idea of case is when I have single values and not to give a lot
of options in many cases.
Maybe it is better not to use case but to use if and I do not know.
Uri
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