89 lines
3.9 KiB
C
89 lines
3.9 KiB
C
/* The <setjmp.h> header relates to the C phenomenon known as setjmp/longjmp.
|
|
* It is used to escape out of the current situation into a previous one.
|
|
*
|
|
* The actual implementations of all these functions and, by extension, parts
|
|
* of this header, are both compiler- and architecture-dependent. Currently
|
|
* two compilers are supported: ACK and GCC. Each of these has their own
|
|
* implementation of the functions in their runtime system library code.
|
|
* As it is impossible to predict the requirements for any other compilers,
|
|
* this header may not be compatible with such other compilers either.
|
|
*
|
|
* The ACK compiler will not enregister any variables inside a function
|
|
* containing a setjmp call, even if those variables are explicitly declared
|
|
* as register variables. Thus for ACK, of all the registers, only the
|
|
* program counter, stack pointer and frame pointer have to be saved into the
|
|
* jmp_buf structure. This makes the jmp_buf structure very small, and
|
|
* moreover, the implementation of the setjmp/longjmp calls (written in EM)
|
|
* architecture-independent and thus very portable. The ACK compiler
|
|
* recognizes only the symbol __setjmp as being such a setjmp call.
|
|
*
|
|
* The GCC compiler recognizes all of the setjmp/_setjmp/__setjmp name
|
|
* variants as calls to setjmp functions, and treats them as special
|
|
* accordingly, but does require that the setjmp implementation save and
|
|
* restore most of the registers. It has no portable setjmp and longjmp
|
|
* functions like ACK, and therefore has to have enough space in the jmp_buf
|
|
* structure to store the registers on any architecture it's ported to.
|
|
*
|
|
* Taking the common denominator of both compilers, the function definitions
|
|
* in this header rely on the presence of merely two functions: __setjmp and
|
|
* longjmp. On the other hand, the size of jmp_buf depends on the compiler
|
|
* used: for ACK, jmp_buf is exactly big enough to store the three mentioned
|
|
* registers; for GCC and any other compiler, the size is chosen in such a
|
|
* way that it's likely to offer enough room to store registers for any
|
|
* architecture. The POSIX sigjmp_buf is identical to jmp_buf in all cases.
|
|
*
|
|
* As far as porting is concerned --
|
|
*
|
|
* All code writers/porters that have to deal with the actual contents of the
|
|
* jmp_buf structure in one way or another, should look at <sys/jmp_buf.h>.
|
|
*
|
|
* Porters of a new compiler to Minix have to make sure the compiler
|
|
* recognizes at least __setjmp as a setjmp call (if applicable) and provide
|
|
* library implementations of __setjmp and longjmp conforming to their
|
|
* declarations below; if this is not possible, compiler-specific code will
|
|
* have to be added to this header.
|
|
*
|
|
* Porters of Minix+GCC to other architectures have to make sure that the
|
|
* __regs array of the jmp_buf structure is large enough to hold all the
|
|
* registers the __setjmp implementation for that architecture has to save.
|
|
*/
|
|
|
|
#ifndef _SETJMP_H
|
|
#define _SETJMP_H
|
|
|
|
#ifndef _MINIX_ANSI_H
|
|
#include <minix/ansi.h>
|
|
#endif
|
|
|
|
typedef struct {
|
|
#if defined(__ACK__)
|
|
_PROTOTYPE(void (*__pc),(void)); /* program counter */
|
|
void *__sp; /* stack pointer */
|
|
void *__lb; /* local base (ACKspeak for frame pointer) */
|
|
long __mask; /* must have size >= sizeof(sigset_t) */
|
|
int __flags;
|
|
#else /* GCC */
|
|
int __flags; /* XXX - long might give better alignment */
|
|
long __mask; /* must have size >= sizeof(sigset_t) */
|
|
void *__regs[16]; /* actual use is architecture dependent */
|
|
#endif
|
|
} jmp_buf[1];
|
|
|
|
_PROTOTYPE( int __setjmp, (jmp_buf _env, int _savemask) );
|
|
_PROTOTYPE( void longjmp, (jmp_buf _env, int _val) );
|
|
|
|
#define setjmp(env) __setjmp((env), 1)
|
|
|
|
#ifdef _MINIX
|
|
#define _setjmp(env) __setjmp((env), 0)
|
|
#define _longjmp(env, val) longjmp((env), (val))
|
|
#endif
|
|
|
|
#ifdef _POSIX_SOURCE
|
|
typedef jmp_buf sigjmp_buf;
|
|
#define sigsetjmp(env, savemask) __setjmp((env), (savemask))
|
|
#define siglongjmp(env, val) longjmp((env), (val))
|
|
#endif /* _POSIX_SOURCE */
|
|
|
|
#endif /* _SETJMP_H */
|