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// 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.
The runtime package contains operations that interact with Go's runtime system,
such as functions to control goroutines. It also includes the low-level type information
used by the reflect package; see reflect's documentation for the programmable
interface to the run-time type system.
package runtime
// Gosched yields the processor, allowing other goroutines to run. It does not
// suspend the current goroutine, so execution resumes automatically.
func Gosched()
// Goexit terminates the goroutine that calls it. No other goroutine is affected.
// Goexit runs all deferred calls before terminating the goroutine.
func Goexit()
// Caller reports file and line number information about function invocations on
// the calling goroutine's stack. The argument skip is the number of stack frames to
// ascend, with 0 identifying the the caller of Caller. The return values report the
// program counter, file name, and line number within the file of the corresponding
// call. The boolean ok is false if it was not possible to recover the information.
func Caller(skip int) (pc uintptr, file string, line int, ok bool)
// Callers fills the slice pc with the program counters of function invocations
// on the calling goroutine's stack. The argument skip is the number of stack frames
// to skip before recording in pc, with 0 starting at the caller of Caller.
// It returns the number of entries written to pc.
func Callers(skip int, pc []uintptr) int
type Func struct { // Keep in sync with runtime.h:struct Func
name string
typ string // go type string
src string // src file name
pcln []byte // pc/ln tab for this func
entry uintptr // entry pc
pc0 uintptr // starting pc, ln for table
ln0 int32
frame int32 // stack frame size
args int32 // number of 32-bit in/out args
locals int32 // number of 32-bit locals
// FuncForPC returns a *Func describing the function that contains the
// given program counter address, or else nil.
func FuncForPC(pc uintptr) *Func
// Name returns the name of the function.
func (f *Func) Name() string { return }
// Entry returns the entry address of the function.
func (f *Func) Entry() uintptr { return f.entry }
// FileLine returns the file name and line number of the
// source code corresponding to the program counter pc.
// The result will not be accurate if pc is not a program
// counter within f.
func (f *Func) FileLine(pc uintptr) (file string, line int) {
// NOTE(rsc): If you edit this function, also edit
// symtab.c:/^funcline. That function also has the
// comments explaining the logic.
targetpc := pc
var pcQuant uintptr = 1
if GOARCH == "arm" {
pcQuant = 4
p := f.pcln
pc = f.pc0
line = int(f.ln0)
i := 0
//print("FileLine start pc=", pc, " targetpc=", targetpc, " line=", line,
// " tab=", p, " ", p[0], " quant=", pcQuant, " GOARCH=", GOARCH, "\n")
for {
for i < len(p) && p[i] > 128 {
pc += pcQuant * uintptr(p[i]-128)
//print("pc<", pc, " targetpc=", targetpc, " line=", line, "\n")
if pc > targetpc || i >= len(p) {
if p[i] == 0 {
if i+5 > len(p) {
line += int(p[i+1]<<24) | int(p[i+2]<<16) | int(p[i+3]<<8) | int(p[i+4])
i += 5
} else if p[i] <= 64 {
line += int(p[i])
} else {
line -= int(p[i] - 64)
//print("pc=", pc, " targetpc=", targetpc, " line=", line, "\n")
pc += pcQuant
file = f.src
// mid returns the current os thread (m) id.
func mid() uint32
// Semacquire waits until *s > 0 and then atomically decrements it.
// It is intended as a simple sleep primitive for use by the synchronization
// library and should not be used directly.
func Semacquire(s *uint32)
// Semrelease atomically increments *s and notifies a waiting goroutine
// if one is blocked in Semacquire.
// It is intended as a simple wakeup primitive for use by the synchronization
// library and should not be used directly.
func Semrelease(s *uint32)
// SetFinalizer sets the finalizer associated with x to f.
// When the garbage collector finds an unreachable block
// with an associated finalizer, it clears the association and runs
// f(x) in a separate goroutine. This makes x reachable again, but
// now without an associated finalizer. Assuming that SetFinalizer
// is not called again, the next time the garbage collector sees
// that x is unreachable, it will free x.
// SetFinalizer(x, nil) clears any finalizer associated with x.
// The argument x must be a pointer to an object allocated by
// calling new or by taking the address of a composite literal.
// The argument f must be a function that takes a single argument
// of x's type and returns no arguments. If either of these is not
// true, SetFinalizer aborts the program.
// Finalizers are run in dependency order: if A points at B, both have
// finalizers, and they are otherwise unreachable, only the finalizer
// for A runs; once A is freed, the finalizer for B can run.
// If a cyclic structure includes a block with a finalizer, that
// cycle is not guaranteed to be garbage collected and the finalizer
// is not guaranteed to run, because there is no ordering that
// respects the dependencies.
// The finalizer for x is scheduled to run at some arbitrary time after
// x becomes unreachable.
// There is no guarantee that finalizers will run before a program exits,
// so typically they are useful only for releasing non-memory resources
// associated with an object during a long-running program.
// For example, an os.File object could use a finalizer to close the
// associated operating system file descriptor when a program discards
// an os.File without calling Close, but it would be a mistake
// to depend on a finalizer to flush an in-memory I/O buffer such as a
// bufio.Writer, because the buffer would not be flushed at program exit.
// A single goroutine runs all finalizers for a program, sequentially.
// If a finalizer must run for a long time, it should do so by starting
// a new goroutine.
// TODO(rsc): allow f to have (ignored) return values
func SetFinalizer(x, f interface{})
func getgoroot() string
// GOROOT returns the root of the Go tree.
// It uses the GOROOT environment variable, if set,
// or else the root used during the Go build.
func GOROOT() string {
s := getgoroot()
if s != "" {
return s
return defaultGoroot
// Version returns the Go tree's version string.
// It is either a sequence number or, when possible,
// a release tag like "release.2010-03-04".
// A trailing + indicates that the tree had local modifications
// at the time of the build.
func Version() string {
return theVersion
// GOOS is the Go tree's operating system target:
// one of darwin, freebsd, linux, and so on.
const GOOS string = theGoos
// GOARCH is the Go tree's architecture target:
// 386, amd64, or arm.
const GOARCH string = theGoarch