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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.
#include "runtime.h"
#include "stack.h"
#include "cgocall.h"
void *initcgo; /* filled in by dynamic linker when Cgo is available */
int64 ncgocall;
void runtime·entersyscall(void);
void runtime·exitsyscall(void);
void
runtime·cgocall(void (*fn)(void*), void *arg)
{
G *oldlock;
if(!runtime·iscgo)
runtime·throw("cgocall unavailable");
if(fn == 0)
runtime·throw("cgocall nil");
ncgocall++;
/*
* Lock g to m to ensure we stay on the same stack if we do a
* cgo callback.
*/
oldlock = m->lockedg;
m->lockedg = g;
g->lockedm = m;
/*
* Announce we are entering a system call
* so that the scheduler knows to create another
* M to run goroutines while we are in the
* foreign code.
*/
runtime·entersyscall();
runtime·runcgo(fn, arg);
runtime·exitsyscall();
m->lockedg = oldlock;
if(oldlock == nil)
g->lockedm = nil;
return;
}
// When a C function calls back into Go, the wrapper function will
// call this. This switches to a Go stack, copies the arguments
// (arg/argsize) on to the stack, calls the function, copies the
// arguments back where they came from, and finally returns to the old
// stack.
void
runtime·cgocallback(void (*fn)(void), void *arg, int32 argsize)
{
Gobuf oldsched, oldg1sched;
G *g1;
void *sp;
if(g != m->g0)
runtime·throw("bad g in cgocallback");
g1 = m->curg;
oldsched = m->sched;
oldg1sched = g1->sched;
runtime·startcgocallback(g1);
sp = g1->sched.sp - argsize;
if(sp < g1->stackguard - StackGuard - StackSystem + 8) // +8 for return address
runtime·throw("g stack overflow in cgocallback");
runtime·mcpy(sp, arg, argsize);
runtime·runcgocallback(g1, sp, fn);
runtime·mcpy(arg, sp, argsize);
runtime·endcgocallback(g1);
m->sched = oldsched;
g1->sched = oldg1sched;
}
void
runtime·Cgocalls(int64 ret)
{
ret = ncgocall;
FLUSH(&ret);
}
void (*_cgo_malloc)(void*);
void (*_cgo_free)(void*);
void*
runtime·cmalloc(uintptr n)
{
struct {
uint64 n;
void *ret;
} a;
a.n = n;
a.ret = nil;
runtime·cgocall(_cgo_malloc, &a);
return a.ret;
}
void
runtime·cfree(void *p)
{
runtime·cgocall(_cgo_free, p);
}
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