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5-14.C
68 lines (64 loc) · 1.59 KB
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5-14.C
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/* Copyright (c) 1992 by AT&T Bell Laboratories. */
/* Advanced C++ Programming Styles and Idioms */
/* James O. Coplien */
/* All rights reserved. */
#include <stddef.h>
#include <memory.h>
class LAPD {
friend class LAPDMemoryManager;
friend class Setup;
friend class Conn;
public:
virtual int size() { return 0; }
void *operator new(size_t);
void operator delete(void *);
LAPD(char *const);
protected:
LAPD() { /* no-op */ }
private:
int:8;
union {
struct {
unsigned char flag;
unsigned int sapi:6;
unsigned int commandResponse:1;
unsigned int zero:1;
unsigned int tei:7;
unsigned int ext:1;
unsigned char control;
} header;
struct {
LAPD *linkf, *linkb;
unsigned short size;
} minfo;
};
unsigned char tag; // minfo system allocated tag
int performCRCCheck() { /* . . . */ return 0; }
};
class Setup: public LAPD {
friend LAPD;
private:
struct SetupPacketBody {
unsigned char rep[4096];
};
SetupPacketBody body;
int size() { return sizeof(Setup); }
Setup(const char *m): LAPD() {
manager.allocateResizeBlock( size() );
::memcpy(&body, m+sizeof(header), sizeof(body));
// . . . .
}
};
class Conn: public LAPD {
friend LAPD;
private:
struct ConnPacketBody {
unsigned char rep[4096];
};
ConnPacketBody body;
int size() { return sizeof(Conn); }
Conn(const char *m): LAPD() {
manager.allocateResizeBlock( size() );
::memcpy(&body, m+sizeof(header), sizeof(body));
}
};