Am Sat, 7 Jun 2014 12:19:11 +0300 schrieb Matti Nykyri <matti.nyk...@iki.fi>:
> On Sat, Jun 07, 2014 at 12:03:29AM +0300, Matti Nykyri wrote:
[...]
> unsigned char get_6bits ()
> {
> static unsigned int rand = 0; //(sizeof(int) = 32)
Just an itty bitty nitpick: since you already require C99 as per the for loop
below, you might as well use uint32_t (from stdint.h) instead of assuming that
sizeof(int) == 32 :) .
> static char bits_avail = 0;
> unsigned char result = 0;
>
> //get 2 bits 3 times: 32 is devidable by 2
> for (int i = 0; i < 3; i++) { // --std=c99
> //Fill buffer if it is empty!
> if (!bits_avail || bits_avail < 0 ) { //if bits_avail < 0 it is
> an error!
> // Use the correct call for ISAAC instead of rand()
> rand = rand();
>
> bits_avail = 32;
> }
>
> result <<= 2; //move two bits to left.
> result = result | (rand & 0x3); //add two least signifigant
> bits to the result.
> rand >>= 2; //move two bits to right.
> bits_avail -= 2;
> }
>
> return result; //result has 6 bits of random data...
> }
>
> char next_character()
> {
> unsigned char idx = 0;
> do {
> idx = get_6bits();
> } while (idx > 61);
>
> return S[idx];
> }
>
> Very simple :)
[...]
--
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup
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