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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 "type.h"
#include "defs_GOOS_GOARCH.h"
#include "os_GOOS.h"
// Will keep all callbacks in a linked list, so they don't get garbage collected.
typedef struct Callback Callback;
struct Callback {
Callback* link;
void* gobody;
byte asmbody;
};
typedef struct Callbacks Callbacks;
struct Callbacks {
Lock;
Callback* link;
int32 n;
};
static Callbacks cbs;
// Call back from windows dll into go.
byte *
runtime·compilecallback(Eface fn, bool cleanstack)
{
FuncType *ft;
Type *t;
int32 argsize, i, n;
byte *p;
Callback *c;
if(fn.type == nil || fn.type->kind != KindFunc)
runtime·panicstring("compilecallback: not a function");
ft = (FuncType*)fn.type;
if(ft->out.len != 1)
runtime·panicstring("compilecallback: function must have one output parameter");
if(((Type**)ft->out.array)[0]->size != sizeof(uintptr))
runtime·panicstring("compilecallback: output parameter size is wrong");
argsize = 0;
for(i=0; i<ft->in.len; i++) {
t = ((Type**)ft->in.array)[i];
if(t->size > sizeof(uintptr))
runtime·panicstring("compilecallback: input parameter size is wrong");
argsize += sizeof(uintptr);
}
// compute size of new fn.
// must match code laid out below.
n = 1+4; // MOVL fn, AX
n += 1+4; // MOVL argsize, DX
n += 1+4; // MOVL callbackasm, CX
n += 2; // CALL CX
n += 1; // RET
if(cleanstack && argsize!=0)
n += 2; // ... argsize
runtime·lock(&cbs);
for(c = cbs.link; c != nil; c = c->link) {
if(c->gobody == fn.data) {
runtime·unlock(&cbs);
return &c->asmbody;
}
}
if(cbs.n >= 2000)
runtime·throw("too many callback functions");
c = runtime·mal(sizeof *c + n);
c->gobody = fn.data;
c->link = cbs.link;
cbs.link = c;
cbs.n++;
runtime·unlock(&cbs);
p = &c->asmbody;
// MOVL fn, AX
*p++ = 0xb8;
*(uint32*)p = (uint32)fn.data;
p += 4;
// MOVL argsize, DX
*p++ = 0xba;
*(uint32*)p = argsize;
p += 4;
// MOVL callbackasm, CX
*p++ = 0xb9;
*(uint32*)p = (uint32)runtime·callbackasm;
p += 4;
// CALL CX
*p++ = 0xff;
*p++ = 0xd1;
// RET argsize?
if(cleanstack && argsize!=0) {
*p++ = 0xc2;
*(uint16*)p = argsize;
} else
*p = 0xc3;
return &c->asmbody;
}
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