boulder dash random number

byte RandSeed1 = 0;
byte RandSeed2 = 0;
byte TempRand1;
byte TempRand2;

void randInit2(byte a,byte b) {
  RandSeed1 = a;
  RandSeed2 = b;
}

asm byte randInt() {
// This is the mathematical random number generator from the Commodore 64
// implementation of Boulder Dash I. The 6510 disassembly is given in
// comments, and the C translation follows.
// http://www.elmerproductions.com/sp/peterb/insideBoulderdash.html#Random%20numbers

  lda RandSeed1
  ror
  ror
  and #$80
  sta TempRand1

  lda RandSeed2
  ror
  and #$7F
  sta TempRand2

  lda RandSeed2
  ror
  ror
  and #$80
  clc
  adc RandSeed2

  adc #$13
  sta RandSeed2

  lda RandSeed1
  adc TempRand1

  adc TempRand2
  sta RandSeed1
  rts
}

byte randIntRange(byte range) {
word v;
byte r;
  r = range;
  v = randInt();
  v = v * r;
  v = v / 256;
  return v.lo;
}

byte randIntRange2(byte lo,byte hi) {
word v;
byte r;
  r = hi-lo+1;
  v = randInt();
  v = v * r;
  v = v / 256;
  v = v + lo;

  return v.lo;
}