Vendor Update

vendor/github.com/ugorji/go/codec/helper_internal.go

@@ -0,0 +1,121 @@
+// Copyright (c) 2012-2015 Ugorji Nwoke. All rights reserved.
+// Use of this source code is governed by a MIT license found in the LICENSE file.
+
+package codec
+
+// All non-std package dependencies live in this file,
+// so porting to different environment is easy (just update functions).
+
+func pruneSignExt(v []byte, pos bool) (n int) {
+	if len(v) < 2 {
+	} else if pos && v[0] == 0 {
+		for ; v[n] == 0 && n+1 < len(v) && (v[n+1]&(1<<7) == 0); n++ {
+		}
+	} else if !pos && v[0] == 0xff {
+		for ; v[n] == 0xff && n+1 < len(v) && (v[n+1]&(1<<7) != 0); n++ {
+		}
+	}
+	return
+}
+
+// validate that this function is correct ...
+// culled from OGRE (Object-Oriented Graphics Rendering Engine)
+// function: halfToFloatI (http://stderr.org/doc/ogre-doc/api/OgreBitwise_8h-source.html)
+func halfFloatToFloatBits(yy uint16) (d uint32) {
+	y := uint32(yy)
+	s := (y >> 15) & 0x01
+	e := (y >> 10) & 0x1f
+	m := y & 0x03ff
+
+	if e == 0 {
+		if m == 0 { // plu or minus 0
+			return s << 31
+		}
+		// Denormalized number -- renormalize it
+		for (m & 0x00000400) == 0 {
+			m <<= 1
+			e -= 1
+		}
+		e += 1
+		const zz uint32 = 0x0400
+		m &= ^zz
+	} else if e == 31 {
+		if m == 0 { // Inf
+			return (s << 31) | 0x7f800000
+		}
+		return (s << 31) | 0x7f800000 | (m << 13) // NaN
+	}
+	e = e + (127 - 15)
+	m = m << 13
+	return (s << 31) | (e << 23) | m
+}
+
+// GrowCap will return a new capacity for a slice, given the following:
+//   - oldCap: current capacity
+//   - unit: in-memory size of an element
+//   - num: number of elements to add
+func growCap(oldCap, unit, num int) (newCap int) {
+	// appendslice logic (if cap < 1024, *2, else *1.25):
+	//   leads to many copy calls, especially when copying bytes.
+	//   bytes.Buffer model (2*cap + n): much better for bytes.
+	// smarter way is to take the byte-size of the appended element(type) into account
+
+	// maintain 3 thresholds:
+	// t1: if cap <= t1, newcap = 2x
+	// t2: if cap <= t2, newcap = 1.75x
+	// t3: if cap <= t3, newcap = 1.5x
+	//     else          newcap = 1.25x
+	//
+	// t1, t2, t3 >= 1024 always.
+	// i.e. if unit size >= 16, then always do 2x or 1.25x (ie t1, t2, t3 are all same)
+	//
+	// With this, appending for bytes increase by:
+	//    100% up to 4K
+	//     75% up to 8K
+	//     50% up to 16K
+	//     25% beyond that
+
+	// unit can be 0 e.g. for struct{}{}; handle that appropriately
+	var t1, t2, t3 int // thresholds
+	if unit <= 1 {
+		t1, t2, t3 = 4*1024, 8*1024, 16*1024
+	} else if unit < 16 {
+		t3 = 16 / unit * 1024
+		t1 = t3 * 1 / 4
+		t2 = t3 * 2 / 4
+	} else {
+		t1, t2, t3 = 1024, 1024, 1024
+	}
+
+	var x int // temporary variable
+
+	// x is multiplier here: one of 5, 6, 7 or 8; incr of 25%, 50%, 75% or 100% respectively
+	if oldCap <= t1 { // [0,t1]
+		x = 8
+	} else if oldCap > t3 { // (t3,infinity]
+		x = 5
+	} else if oldCap <= t2 { // (t1,t2]
+		x = 7
+	} else { // (t2,t3]
+		x = 6
+	}
+	newCap = x * oldCap / 4
+
+	if num > 0 {
+		newCap += num
+	}
+
+	// ensure newCap is a multiple of 64 (if it is > 64) or 16.
+	if newCap > 64 {
+		if x = newCap % 64; x != 0 {
+			x = newCap / 64
+			newCap = 64 * (x + 1)
+		}
+	} else {
+		if x = newCap % 16; x != 0 {
+			x = newCap / 16
+			newCap = 16 * (x + 1)
+		}
+	}
+	return
+}