1 files changed, 139 insertions, 0 deletions
diff --git a/src/runtime/slice.go b/src/runtime/slice.go
new file mode 100644
index 000000000..3b88927c6
--- /dev/null
+++ b/src/runtime/slice.go
@@ -0,0 +1,139 @@
+// 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 runtime
+
+import (
+	"unsafe"
+)
+
+type sliceStruct struct {
+	array unsafe.Pointer
+	len   int
+	cap   int
+}
+
+// TODO: take uintptrs instead of int64s?
+func makeslice(t *slicetype, len64 int64, cap64 int64) sliceStruct {
+	// NOTE: The len > MaxMem/elemsize check here is not strictly necessary,
+	// but it produces a 'len out of range' error instead of a 'cap out of range' error
+	// when someone does make([]T, bignumber). 'cap out of range' is true too,
+	// but since the cap is only being supplied implicitly, saying len is clearer.
+	// See issue 4085.
+	len := int(len64)
+	if len64 < 0 || int64(len) != len64 || t.elem.size > 0 && uintptr(len) > maxMem/uintptr(t.elem.size) {
+		panic(errorString("makeslice: len out of range"))
+	}
+	cap := int(cap64)
+	if cap < len || int64(cap) != cap64 || t.elem.size > 0 && uintptr(cap) > maxMem/uintptr(t.elem.size) {
+		panic(errorString("makeslice: cap out of range"))
+	}
+	p := newarray(t.elem, uintptr(cap))
+	return sliceStruct{p, len, cap}
+}
+
+// TODO: take uintptr instead of int64?
+func growslice(t *slicetype, old sliceStruct, n int64) sliceStruct {
+	if n < 1 {
+		panic(errorString("growslice: invalid n"))
+	}
+
+	cap64 := int64(old.cap) + n
+	cap := int(cap64)
+
+	if int64(cap) != cap64 || cap < old.cap || t.elem.size > 0 && uintptr(cap) > maxMem/uintptr(t.elem.size) {
+		panic(errorString("growslice: cap out of range"))
+	}
+
+	if raceenabled {
+		callerpc := getcallerpc(unsafe.Pointer(&t))
+		racereadrangepc(old.array, uintptr(old.len*int(t.elem.size)), callerpc, funcPC(growslice))
+	}
+
+	et := t.elem
+	if et.size == 0 {
+		return sliceStruct{old.array, old.len, cap}
+	}
+
+	newcap := old.cap
+	if newcap+newcap < cap {
+		newcap = cap
+	} else {
+		for {
+			if old.len < 1024 {
+				newcap += newcap
+			} else {
+				newcap += newcap / 4
+			}
+			if newcap >= cap {
+				break
+			}
+		}
+	}
+
+	if uintptr(newcap) >= maxMem/uintptr(et.size) {
+		panic(errorString("growslice: cap out of range"))
+	}
+	lenmem := uintptr(old.len) * uintptr(et.size)
+	capmem := goroundupsize(uintptr(newcap) * uintptr(et.size))
+	newcap = int(capmem / uintptr(et.size))
+	var p unsafe.Pointer
+	if et.kind&kindNoPointers != 0 {
+		p = rawmem(capmem)
+		memclr(add(p, lenmem), capmem-lenmem)
+	} else {
+		// Note: can't use rawmem (which avoids zeroing of memory), because then GC can scan unitialized memory
+		p = newarray(et, uintptr(newcap))
+	}
+	memmove(p, old.array, lenmem)
+
+	return sliceStruct{p, old.len, newcap}
+}
+
+func slicecopy(to sliceStruct, fm sliceStruct, width uintptr) int {
+	if fm.len == 0 || to.len == 0 || width == 0 {
+		return 0
+	}
+
+	n := fm.len
+	if to.len < n {
+		n = to.len
+	}
+
+	if raceenabled {
+		callerpc := getcallerpc(unsafe.Pointer(&to))
+		pc := funcPC(slicecopy)
+		racewriterangepc(to.array, uintptr(n*int(width)), callerpc, pc)
+		racereadrangepc(fm.array, uintptr(n*int(width)), callerpc, pc)
+	}
+
+	size := uintptr(n) * width
+	if size == 1 { // common case worth about 2x to do here
+		// TODO: is this still worth it with new memmove impl?
+		*(*byte)(to.array) = *(*byte)(fm.array) // known to be a byte pointer
+	} else {
+		memmove(to.array, fm.array, size)
+	}
+	return int(n)
+}
+
+func slicestringcopy(to []byte, fm string) int {
+	if len(fm) == 0 || len(to) == 0 {
+		return 0
+	}
+
+	n := len(fm)
+	if len(to) < n {
+		n = len(to)
+	}
+
+	if raceenabled {
+		callerpc := getcallerpc(unsafe.Pointer(&to))
+		pc := funcPC(slicestringcopy)
+		racewriterangepc(unsafe.Pointer(&to[0]), uintptr(n), callerpc, pc)
+	}
+
+	memmove(unsafe.Pointer(&to[0]), unsafe.Pointer((*stringStruct)(unsafe.Pointer(&fm)).str), uintptr(n))
+	return n
+}