mirror of
https://github.com/golang/go
synced 2024-10-04 22:21:22 -06:00
2e20386fc7
These functions are used to call from a C function back to a Go function. This only includes 386 support. R=rsc CC=golang-dev https://golang.org/cl/834045
113 lines
1.9 KiB
C
113 lines
1.9 KiB
C
// Copyright 2009 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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#include "runtime.h"
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#include "cgocall.h"
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void *initcgo; /* filled in by dynamic linker when Cgo is available */
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int64 ncgocall;
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void ·entersyscall(void);
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void ·exitsyscall(void);
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void
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cgocall(void (*fn)(void*), void *arg)
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{
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G *oldlock;
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if(initcgo == nil)
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throw("cgocall unavailable");
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ncgocall++;
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/*
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* Lock g to m to ensure we stay on the same stack if we do a
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* cgo callback.
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*/
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oldlock = m->lockedg;
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m->lockedg = g;
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g->lockedm = m;
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/*
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* Announce we are entering a system call
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* so that the scheduler knows to create another
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* M to run goroutines while we are in the
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* foreign code.
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*/
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·entersyscall();
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runcgo(fn, arg);
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·exitsyscall();
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m->lockedg = oldlock;
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if(oldlock == nil)
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g->lockedm = nil;
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return;
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}
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// When a C function calls back into Go, the wrapper function will
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// call this. This switches to a Go stack, copies the arguments
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// (arg/argsize) on to the stack, calls the function, copies the
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// arguments back where they came from, and finally returns to the old
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// stack.
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void
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cgocallback(void (*fn)(void), void *arg, int32 argsize)
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{
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Gobuf oldsched;
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G *g1;
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void *sp;
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if(g != m->g0)
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throw("bad g in cgocallback");
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oldsched = m->sched;
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g1 = m->curg;
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startcgocallback(g1);
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sp = g1->sched.sp - argsize;
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if(sp < g1->stackguard)
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throw("g stack overflow in cgocallback");
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mcpy(sp, arg, argsize);
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runcgocallback(g1, sp, fn);
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mcpy(arg, sp, argsize);
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endcgocallback(g1);
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m->sched = oldsched;
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}
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void
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·Cgocalls(int64 ret)
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{
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ret = ncgocall;
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FLUSH(&ret);
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}
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void (*_cgo_malloc)(void*);
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void (*_cgo_free)(void*);
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void*
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cmalloc(uintptr n)
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{
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struct a {
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uint64 n;
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void *ret;
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} a;
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a.n = n;
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a.ret = nil;
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cgocall(_cgo_malloc, &a);
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return a.ret;
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}
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void
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cfree(void *p)
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{
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cgocall(_cgo_free, p);
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}
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