by 12345 » Wed Jun 22, 2005 1:11 pm
Honestly, it almost always comes back to random number generation, whether it's lost conc, failed skills, or rerolling. Some may be interested that there's a lot of Diku derivatives that use their own random number generators... For instance, this is taken from a Mythran codebase, but I believe Furey was a Merc coder. Either way, it's Furey's code:
[code:2aivgsk2]/*
* I've gotten too many bad reports on OS-supplied random number generators.
* This is the Mitchell-Moore algorithm from Knuth Volume II.
* Best to leave the constants alone unless you've read Knuth.
* -- Furey
*/
static int rgiState[2+55];
void init_mm( )
{
int *piState;
int iState;
piState = &rgiState[2];
piState[-2] = 55 - 55;
piState[-1] = 55 - 24;
piState[0] = ( (int) current_time ) & ( ( 1 << 30 ) - 1 );
piState[1] = 1;
for ( iState = 2; iState < 55; iState++ )
{
piState[iState] = ( piState[iState-1] + piState[iState-2] )
& ( ( 1 << 30 ) - 1 );
}
return;
}
int number_mm( void )
{
int *piState;
int iState1;
int iState2;
int iRand;
piState = &rgiState[2];
iState1 = piState[-2];
iState2 = piState[-1];
iRand = ( piState[iState1] + piState[iState2] )
& ( ( 1 << 30 ) - 1 );
piState[iState1] = iRand;
if ( ++iState1 == 55 )
iState1 = 0;
if ( ++iState2 == 55 )
iState2 = 0;
piState[-2] = iState1;
piState[-1] = iState2;
return iRand >> 6;
}
/*
* Roll some dice.
*/
int dice( int number, int size )
{
int idice;
int sum;
switch ( size )
{
case 0: return 0;
case 1: return number;
}
for ( idice = 0, sum = 0; idice < number; idice++ )
sum += number_range( 1, size );
return sum;
}
/*
* Generate a random number.
*/
int number_range( int from, int to )
{
int power;
int number;
if ( ( to = to - from + 1 ) <= 1 )
return from;
for ( power = 2; power < to; power <<= 1 )
;
while ( ( number = number_mm( ) & ( power - 1 ) ) >= to )
;
return from + number;
}
/*
* Generate a percentile roll.
*/
int number_percent( void )
{
int percent;
while ( ( percent = number_mm( ) & ( 128-1 ) ) > 99 )
;
return 1 + percent;
}[/code:2aivgsk2]
Kein Mehrheit Fur Die Mitleid -KMFDM