dos33fsprogs/gr-sim/tfv/tfv_random.c

20 lines
466 B
C
Raw Normal View History

// http://codebase64.org/doku.php?id=base:small_fast_8-bit_prng
int random_8(void) {
static int seed=0x1f;
static int newseed;
newseed=seed; // lda seed
if (newseed==0) goto doEor; // beq doEor
newseed<<=1; // asl
if (newseed==0) goto noEor; //beq noEor
// if the input was $80, skip the EOR
if (!(newseed&0x100)) goto noEor; // bcc noEor
doEor:
newseed^=0x1d; // eor #$1d
noEor:
seed=(newseed&0xff); // sta seed
return seed;
}