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/***********************************************************************/
/* */
/* Objective Caml */
/* */
/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
/* */
/* Copyright 1996 Institut National de Recherche en Informatique et */
/* en Automatique. All rights reserved. This file is distributed */
/* under the terms of the GNU Library General Public License. */
/* */
/***********************************************************************/
/* $Id$ */
/* Buffered input/output */
#ifndef _io_
#define _io_
#include "misc.h"
#include "mlvalues.h"
#ifndef IO_BUFFER_SIZE
#define IO_BUFFER_SIZE 4096
#endif
struct channel {
int fd; /* Unix file descriptor */
long offset; /* Absolute position of fd in the file */
char * end; /* Physical end of the buffer */
char * curr; /* Current position in the buffer */
char * max; /* Logical end of the buffer (for input) */
void * mutex; /* Placeholder for mutex (for systhreads) */
char buff[IO_BUFFER_SIZE]; /* The buffer itself */
};
/* For an output channel:
[offset] is the absolute position of the beginning of the buffer [buff].
For an input channel:
[offset] is the absolute position of the logical end of the buffer, [max].
*/
/* Functions and macros that can be called from C. Take arguments of
type struct channel *. No locking is performed. */
#define putch(channel, ch) do{ \
if ((channel)->curr >= (channel)->end) flush_partial(channel); \
*((channel)->curr)++ = (ch); \
}while(0)
#define getch(channel) \
((channel)->curr >= (channel)->max \
? refill(channel) \
: (unsigned char) *((channel))->curr++)
CAMLextern struct channel * open_descriptor (int);
CAMLextern void close_channel (struct channel *);
CAMLextern int channel_binary_mode (struct channel *);
CAMLextern int flush_partial (struct channel *);
CAMLextern void flush (struct channel *);
CAMLextern void putword (struct channel *, uint32);
CAMLextern int putblock (struct channel *, char *, long);
CAMLextern void really_putblock (struct channel *, char *, long);
CAMLextern unsigned char refill (struct channel *);
CAMLextern uint32 getword (struct channel *);
CAMLextern int getblock (struct channel *, char *, long);
CAMLextern int really_getblock (struct channel *, char *, long);
/* Extract a struct channel * from the heap object representing it */
#define Channel(v) (*((struct channel **) (Data_custom_val(v))))
/* The locking machinery */
CAMLextern void (*channel_mutex_free) (struct channel *);
CAMLextern void (*channel_mutex_lock) (struct channel *);
CAMLextern void (*channel_mutex_unlock) (struct channel *);
CAMLextern void (*channel_mutex_unlock_exn) (void);
#define Lock(channel) \
if (channel_mutex_lock != NULL) (*channel_mutex_lock)(channel)
#define Unlock(channel) \
if (channel_mutex_unlock != NULL) (*channel_mutex_unlock)(channel)
#define Unlock_exn() \
if (channel_mutex_unlock_exn != NULL) (*channel_mutex_unlock_exn)()
#endif /* _io_ */
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