func (z *Big) needsInc(x, r int64, pos, odd bool) bool { m := 1 if r > math.MinInt64/2 || r <= math.MaxInt64/2 { m = arith.AbsCmp(r<<1, x) } return z.ctx.mode.needsInc(m, pos, odd) }
// cmpNorm compares x and y in the range [0.1, 0.999...] and // returns true if x > y. func cmpNorm(x int64, xs int32, y int64, ys int32) (ok bool) { if debug && (x == 0 || y == 0) { panic("x and/or y cannot be zero") } if diff := xs - ys; diff != 0 { if diff < 0 { x, ok = checked.MulPow10(x, -diff) } else { y, ok = checked.MulPow10(y, diff) } } if x != c.Inflated { if y != c.Inflated { return arith.AbsCmp(x, y) > 0 } return false } return true }
// Cmp compares d and x and returns: // // -1 if z < x // 0 if z == x // +1 if z > x // // It does not modify d or x. func (z *Big) Cmp(x *Big) int { // Check for same pointers. if z == x { return 0 } // Same scales means we can compare straight across. if z.scale == x.scale { if z.isCompact() && x.isCompact() { if z.compact > x.compact { return +1 } if z.compact < x.compact { return -1 } return 0 } if z.isInflated() && x.isInflated() { if z.mantissa.Sign() != x.mantissa.Sign() { return z.mantissa.Sign() } if z.scale < 0 { return z.mantissa.Cmp(&x.mantissa) } zb := z.mantissa.Bits() xb := x.mantissa.Bits() min := len(zb) if len(xb) < len(zb) { min = len(xb) } i := 0 for i < min-1 && zb[i] == xb[i] { i++ } if zb[i] > xb[i] { return +1 } if zb[i] < xb[i] { return -1 } return 0 } } // Different scales -- check signs and/or if they're // both zero. ds := z.Sign() xs := x.Sign() switch { case ds > xs: return +1 case ds < xs: return -1 case ds == 0 && xs == 0: return 0 } // Scales aren't equal, the signs are the same, and both // are non-zero. dl := int32(z.Prec()) - z.scale xl := int32(x.Prec()) - x.scale if dl > xl { return +1 } if dl < xl { return -1 } // We need to inflate one of the numbers. dc := z.compact // hi xc := x.compact // lo var swap bool hi, lo := z, x if hi.scale < lo.scale { hi, lo = lo, hi dc, xc = xc, dc swap = true // d is lo } diff := hi.scale - lo.scale if diff <= c.BadScale { var ok bool xc, ok = checked.MulPow10(xc, diff) if !ok && dc == c.Inflated { // d is lo if swap { zm := new(big.Int).Set(&z.mantissa) return checked.MulBigPow10(zm, diff).Cmp(&x.mantissa) } // x is lo xm := new(big.Int).Set(&x.mantissa) return z.mantissa.Cmp(checked.MulBigPow10(xm, diff)) } } if swap { dc, xc = xc, dc } if dc != c.Inflated { if xc != c.Inflated { return arith.AbsCmp(dc, xc) } return big.NewInt(dc).Cmp(&x.mantissa) } if xc != c.Inflated { return z.mantissa.Cmp(big.NewInt(xc)) } return z.mantissa.Cmp(&x.mantissa) }