mirror of
https://github.com/golang/go
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93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"unsafe"
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)
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type callbacks struct {
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lock
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ctxt [cb_max]*wincallbackcontext
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n int
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}
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func (c *wincallbackcontext) isCleanstack() bool {
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return c.cleanstack == 1
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}
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func (c *wincallbackcontext) setCleanstack(cleanstack bool) {
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if cleanstack {
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c.cleanstack = 1
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} else {
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c.cleanstack = 0
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}
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}
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var (
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cbs callbacks
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cbctxts **wincallbackcontext = &cbs.ctxt[0] // to simplify access to cbs.ctxt in sys_windows_*.s
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callbackasm byte // type isn't really byte, it's code in runtime
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)
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// callbackasmAddr returns address of runtime.callbackasm
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// function adjusted by i.
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// runtime.callbackasm is just a series of CALL instructions
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// (each is 5 bytes long), and we want callback to arrive at
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// correspondent call instruction instead of start of
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// runtime.callbackasm.
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func callbackasmAddr(i int) uintptr {
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return uintptr(add(unsafe.Pointer(&callbackasm), uintptr(i*5)))
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}
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func compileCallback(fn eface, cleanstack bool) (code uintptr) {
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if fn._type == nil || (fn._type.kind&kindMask) != kindFunc {
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panic("compilecallback: not a function")
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}
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ft := (*functype)(unsafe.Pointer(fn._type))
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if len(ft.out) != 1 {
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panic("compilecallback: function must have one output parameter")
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}
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uintptrSize := uint(unsafe.Sizeof(uintptr(0)))
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if t := (**_type)(unsafe.Pointer(&ft.out[0])); (*t).size != uintptrSize {
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panic("compilecallback: output parameter size is wrong")
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}
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argsize := uint(0)
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for _, t := range (*[1024](*_type))(unsafe.Pointer(&ft.in[0]))[:len(ft.in)] {
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if (*t).size != uintptrSize {
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panic("compilecallback: input parameter size is wrong")
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}
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argsize += uintptrSize
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}
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golock(&cbs.lock)
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defer gounlock(&cbs.lock)
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n := cbs.n
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for i := 0; i < n; i++ {
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if cbs.ctxt[i].gobody == fn.data && cbs.ctxt[i].isCleanstack() == cleanstack {
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return callbackasmAddr(i)
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}
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}
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if n >= cb_max {
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gothrow("too many callback functions")
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}
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c := new(wincallbackcontext)
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c.gobody = fn.data
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c.argsize = argsize
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c.setCleanstack(cleanstack)
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if cleanstack && argsize != 0 {
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c.restorestack = argsize
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} else {
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c.restorestack = 0
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}
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cbs.ctxt[n] = c
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cbs.n++
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return callbackasmAddr(n)
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}
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