Stream.h

#ifndef __MDFN_STREAM_H
#define __MDFN_STREAM_H

// TODO/WIP

// TODO?: BufferedStream, no virtual functions, yes inline functions, constructor takes a Stream* argument.

#include <errno.h>

#include <stdio.h>	// For SEEK_* defines, which we will use in Stream out of FORCE OF HABIT.
#include <string>

#include "octoshock.h"

class Stream
{
 public:

 Stream();
 virtual ~Stream();

 enum
 {
  ATTRIBUTE_READABLE = 	1U <<  0,
  ATTRIBUTE_WRITEABLE =	1U <<  1,
  ATTRIBUTE_SEEKABLE =	1U <<  2,
  ATTRIBUTE_SLOW_SEEK =	1U <<  3,
  ATTRIBUTE_SLOW_SIZE =	1U <<  4
 };
 virtual uint64 attributes(void) = 0;

 virtual uint8 *map(void) = 0;	// Map the entirety of the stream data into the address space of the process, if possible, and return a pointer.
				// (the returned pointer must be cached, and returned on any subsequent calls to map() without an unmap()
				// in-between, to facilitate a sort of "feature-testing", to determine if an alternative like "MemoryStream"
				// should be used).
				//
				// If the mapping fails for whatever reason, return NULL rather than throwing an exception.
				//

 virtual void unmap(void) = 0;	// Unmap the stream data from the address space.  (Possibly invalidating the pointer returned from map()).
				// (must automatically be called, if necessary, from the destructor).
				//
				// If the data can't be "unmapped" as such because it was never mmap()'d or similar in the first place(such as with MemoryStream),
				// then this will be a nop.

 virtual uint64 read(void *data, uint64 count, bool error_on_eos = true) = 0;
 virtual void write(const void *data, uint64 count) = 0;

 virtual void seek(int64 offset, int whence = SEEK_SET) = 0;
 inline void rewind(void)
 {
  seek(0, SEEK_SET);
 }
 virtual int64 tell(void) = 0;
 virtual int64 size(void) = 0;
 virtual void close(void) = 0;	// Flushes(in the case of writeable streams) and closes the stream.
				// Necessary since this operation can fail(running out of disk space, for instance),
				// and throw an exception in the destructor would be a Bad Idea(TM).
				//
				// Manually calling this function isn't strictly necessary, but recommended when the
				// stream is writeable; it will be called automatically from the destructor, with any
				// exceptions thrown caught and logged.

 //
 // Utility functions(TODO):
 //
 INLINE uint8 get_u8(void)
 {
  uint8 ret;

  read(&ret, sizeof(ret));

  return ret;
 }

 INLINE void put_u8(uint8 c)
 {
  write(&c, sizeof(c));
 }


 template<typename T>
 INLINE T get_NE(void)
 {
  T ret;

  read(&ret, sizeof(ret));

  return ret;
 }

 template<typename T>
 INLINE void put_NE(T c)
 {
  write(&c, sizeof(c));
 }


 template<typename T>
 INLINE T get_RE(void)
 {
  uint8 tmp[sizeof(T)];
  T ret = 0;

  read(tmp, sizeof(tmp));

  for(unsigned i = 0; i < sizeof(T); i++)
   ret |= (T)tmp[i] << (i * 8);

  return ret;
 }

 template<typename T>
 INLINE void put_RE(T c)
 {
  uint8 tmp[sizeof(T)];

  for(unsigned i = 0; i < sizeof(T); i++)
   tmp[i] = ((uint8 *)&c)[sizeof(T) - 1 - i];

  write(tmp, sizeof(tmp));
 }

 template<typename T>
 INLINE T get_LE(void)
 {
  #ifdef LSB_FIRST
  return get_NE<T>();
  #else
  return get_RE<T>();
  #endif
 }

 template<typename T>
 INLINE void put_LE(T c)
 {
  #ifdef LSB_FIRST
  return put_NE<T>(c);
  #else
  return put_RE<T>(c);
  #endif
 }

 template<typename T>
 INLINE T get_BE(void)
 {
  #ifndef LSB_FIRST
  return get_NE<T>();
  #else
  return get_RE<T>();
  #endif
 }

 template<typename T>
 INLINE void put_BE(T c)
 {
  #ifndef LSB_FIRST
  return put_NE<T>(c);
  #else
  return put_RE<T>(c);
  #endif
 }

 // Reads a line into "str", overwriting its contents; returns the line-end char('\n' or '\r' or '\0'), or 256 on EOF and
 // data has been read into "str", and -1 on EOF when no data has been read into "str".
 // The line-end char won't be added to "str".
 // It's up to the caller to handle extraneous empty lines caused by DOS-format text lines(\r\n).
 // ("str" is passed by reference for the possibility of improved performance by reusing alloced memory for the std::string, though part
 //  of it would be up to the STL implementation).
 // Implemented as virtual so that a higher-performance version can be implemented if possible(IE with MemoryStream)
 virtual int get_line(std::string &str);

 virtual void put_line(const std::string& str);

 virtual void print_format(const char *format, ...);

#if 0
 int scanf(const char *format, ...) MDFN_FORMATSTR(gnu_scanf, 2, 3);
 void put_string(const char *str);
 void put_string(const std::string &str);
#endif
};

// StreamFilter takes ownership of the Stream pointer passed, and will delete it in its destructor.
class StreamFilter : public Stream
{
 public:

 StreamFilter();
 StreamFilter(Stream *target_arg);
 virtual ~StreamFilter();

 virtual uint64 read(void *data, uint64 count, bool error_on_eos = true) = 0;
 virtual void write(const void *data, uint64 count) = 0;
 virtual void seek(int64 offset, int whence) = 0;
 virtual int64 tell(void) = 0;
 virtual int64 size(void) = 0;
 virtual void close(void) = 0;

 virtual Stream *steal(void);

 private:
 Stream *target_stream;
};

#endif