1 files changed, 131 insertions, 0 deletions
diff --git a/src/math/floor.go b/src/math/floor.go
new file mode 100644
index 0000000..18e89ef
--- /dev/null
+++ b/src/math/floor.go
@@ -0,0 +1,131 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package math
+
+// Floor returns the greatest integer value less than or equal to x.
+//
+// Special cases are:
+//	Floor(±0) = ±0
+//	Floor(±Inf) = ±Inf
+//	Floor(NaN) = NaN
+func Floor(x float64) float64
+
+func floor(x float64) float64 {
+	if x == 0 || IsNaN(x) || IsInf(x, 0) {
+		return x
+	}
+	if x < 0 {
+		d, fract := Modf(-x)
+		if fract != 0.0 {
+			d = d + 1
+		}
+		return -d
+	}
+	d, _ := Modf(x)
+	return d
+}
+
+// Ceil returns the least integer value greater than or equal to x.
+//
+// Special cases are:
+//	Ceil(±0) = ±0
+//	Ceil(±Inf) = ±Inf
+//	Ceil(NaN) = NaN
+func Ceil(x float64) float64
+
+func ceil(x float64) float64 {
+	return -Floor(-x)
+}
+
+// Trunc returns the integer value of x.
+//
+// Special cases are:
+//	Trunc(±0) = ±0
+//	Trunc(±Inf) = ±Inf
+//	Trunc(NaN) = NaN
+func Trunc(x float64) float64
+
+func trunc(x float64) float64 {
+	if x == 0 || IsNaN(x) || IsInf(x, 0) {
+		return x
+	}
+	d, _ := Modf(x)
+	return d
+}
+
+// Round returns the nearest integer, rounding half away from zero.
+//
+// Special cases are:
+//	Round(±0) = ±0
+//	Round(±Inf) = ±Inf
+//	Round(NaN) = NaN
+func Round(x float64) float64 {
+	// Round is a faster implementation of:
+	//
+	// func Round(x float64) float64 {
+	//   t := Trunc(x)
+	//   if Abs(x-t) >= 0.5 {
+	//     return t + Copysign(1, x)
+	//   }
+	//   return t
+	// }
+	bits := Float64bits(x)
+	e := uint(bits>>shift) & mask
+	if e < bias {
+		// Round abs(x) < 1 including denormals.
+		bits &= signMask // +-0
+		if e == bias-1 {
+			bits |= uvone // +-1
+		}
+	} else if e < bias+shift {
+		// Round any abs(x) >= 1 containing a fractional component [0,1).
+		//
+		// Numbers with larger exponents are returned unchanged since they
+		// must be either an integer, infinity, or NaN.
+		const half = 1 << (shift - 1)
+		e -= bias
+		bits += half >> e
+		bits &^= fracMask >> e
+	}
+	return Float64frombits(bits)
+}
+
+// RoundToEven returns the nearest integer, rounding ties to even.
+//
+// Special cases are:
+//	RoundToEven(±0) = ±0
+//	RoundToEven(±Inf) = ±Inf
+//	RoundToEven(NaN) = NaN
+func RoundToEven(x float64) float64 {
+	// RoundToEven is a faster implementation of:
+	//
+	// func RoundToEven(x float64) float64 {
+	//   t := math.Trunc(x)
+	//   odd := math.Remainder(t, 2) != 0
+	//   if d := math.Abs(x - t); d > 0.5 || (d == 0.5 && odd) {
+	//     return t + math.Copysign(1, x)
+	//   }
+	//   return t
+	// }
+	bits := Float64bits(x)
+	e := uint(bits>>shift) & mask
+	if e >= bias {
+		// Round abs(x) >= 1.
+		// - Large numbers without fractional components, infinity, and NaN are unchanged.
+		// - Add 0.499.. or 0.5 before truncating depending on whether the truncated
+		//   number is even or odd (respectively).
+		const halfMinusULP = (1 << (shift - 1)) - 1
+		e -= bias
+		bits += (halfMinusULP + (bits>>(shift-e))&1) >> e
+		bits &^= fracMask >> e
+	} else if e == bias-1 && bits&fracMask != 0 {
+		// Round 0.5 < abs(x) < 1.
+		bits = bits&signMask | uvone // +-1
+	} else {
+		// Round abs(x) <= 0.5 including denormals.
+		bits &= signMask // +-0
+	}
+	return Float64frombits(bits)
+}