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%%	options

copyright owner	=	Dirk Krause
copyright year	=	2015-xxxx
license		=	bsd



%%	header

/**	@file
	Generic dk4_stream_t interface for
	input and output operations.

	CRT on Windows: Optional.
*/

#ifndef DK4CONF_H_INCLUDED
#include "dk4conf.h"
#endif

#ifndef DK4TYPES_H_INCLUDED
#include "dk4types.h"
#endif

#ifndef DK4ERROR_H_INCLUDED
#include "dk4error.h"
#endif

#ifndef STDLIB_H_INCLUDED
#include <stdlib.h>
#define	STDLIB_H_INCLUDED 1
#endif

/**	API for stream function.
*/
typedef struct {
  void		*d;		/**< In: Low level data. */
  char		*b;		/**< In: Buffer for data to write or read. */
  size_t	 sz_in;		/**< In: Number of bytes to write or read. */
  size_t	 sz_out;	/**< Out: Number of bytes written or read. */
  int		 cmd;		/**< In: Command to execute. */
  int		 res;		/**< Out: Low level operation result. */
} dk4_stream_api_t;

/**	Function to execute one low level command.
*/
typedef void dk4_stream_api_fct_t(dk4_stream_api_t *);

/**	Generic I/O stream.
*/
typedef struct {
  void			*d;	/**< Low level data object. */
  dk4_stream_api_fct_t	*fct;	/**< Function for low level operations. */
  char			*bi;	/**< Buffer for input. */
  char			*bo;	/**< Buffer for output. */
  dk4_um_t		 bwr;	/**< Number of bytes written. */
  size_t		 szbi;	/**< Input buffer size. */
  size_t		 szbo;	/**< Output buffer size. */
  size_t		 usbi;	/**< Bytes used in input buffer. */
  size_t		 usbo;	/**< Bytes used in output buffer. */
  size_t		 rebi;	/**< Read bytes from input buffer. */
  int			 fl;	/**< Flags for allowed operations. */
  int			 feoi;	/**< Flag: Found end of input. */
  int			 bwo;	/**< Flag: Numeric overflow in bwr. */
  int			 oenc;	/**< Output encoding for 32 bit characters. */
  int			 zreof;	/**< Flag: Zero bytes read indicates EOF. */
} dk4_stream_t;

#ifdef __cplusplus
extern "C" {
#endif

/**	Open new stream, allocate memory.
	@param	obj	Low level object.
	@param	fct	Low level function.
	@param	fl	Read/write flags: DK4_STREAM_READ, DK4_STREAM_WRITE
			or (DK4_STREAM_READ | DK4_STREAM_WRITE).
	@param	ibs	Input buffer size (0 for default).
	@param	obs	Output buffer size (0 for default).
	@param	erp	Error report, may be NULL.
	@return	Pointer to new stream on success, NULL on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if obj or fct is NULL or fl is invalid,
	- DK4_E_MATH_OVERFLOW<br>
	  if ibs or obs is too large,
	- DK4_E_MEMORY_ALLOCATION_FAILED<br>
	  if allocation of input or output buffer failed.
*/
dk4_stream_t *
dk4stream_open(
  void			*obj,
  dk4_stream_api_fct_t	*fct,
  int			 fl,
  size_t		 ibs,
  size_t		 obs,
  dk4_er_t		*erp
);

/**	Close data stream, release memory.
	@param	strm	Stream to close.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL,
	- DK4_E_WRITE_FAILED<br>
	  if writing one ore multiple bytes to the stream failed,
	- DK4_E_FLUSH_FAILED<br>
	  if flushing data downwards failed,
	- DK4_E_CLOSE_FAILED<br>
	  if closing downward data failed.
*/
int
dk4stream_close(dk4_stream_t *strm, dk4_er_t *erp);

/**	Write one byte to output stream.
	@param	strm	Output stream.
	@param	c	Byte to write.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for writing,
	- DK4_E_WRITE_FAILED<br>
	  if writing one ore multiple bytes to the stream failed,
	- DK4_E_FLUSH_FAILED<br>
	  if flusing data downwards failed.
*/
int
dk4stream_write_byte(dk4_stream_t *strm, char c, dk4_er_t *erp);

/**	Write a buffer to output stream.
	@param	strm	Output stream.
	@param	b	Buffer start address.
	@param	sz	Number of bytes to write.
	@param	erp	Error report, may be NULL.
	@return 1 on success (all bytes written), 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for writing,
	- DK4_E_WRITE_FAILED<br>
	  if writing one ore multiple bytes to the stream failed,
	- DK4_E_FLUSH_FAILED<br>
	  if flusing data downwards failed.
*/
int
dk4stream_write(dk4_stream_t *strm, const void *b, size_t sz, dk4_er_t *erp);


/**	Write a char string to the stream.
	@param	strm	Output stream.
	@param	str	String to write.
	@param	erp	Error report, may be NULL.
	@return 1 on success (all bytes written), 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for writing,
	- DK4_E_WRITE_FAILED<br>
	  if writing one ore multiple bytes to the stream failed,
	- DK4_E_FLUSH_FAILED<br>
	  if flusing data downwards failed.
*/
int
dk4stream_write_char_string(dk4_stream_t *strm, const char *str, dk4_er_t *erp);

/**	Flush stream input and output data.
	@param	strm	Stream to flush.
	@param	flfl	Flush type: 0=just flush output buffer
	contents to low level object, 1=0+flush low level object,
	2=1+flush all low level objects recursively (for output filtering).
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL.
	- DK4_E_WRITE_FAILED<br>
	  if writing one ore multiple bytes to the stream failed
	- DK4_E_FLUSH_FAILED<br>
	  if flusing data downwards failed.
*/
int
dk4stream_flush(dk4_stream_t *strm, int flfl, dk4_er_t *erp);

/**	Flush stream output data.
	@param	strm	Stream to flush.
	@param	flfl	Flush type: 0=just flush output buffer
	contents to low level object, 1=0+flush low level object,
	2=1+flush all low level objects recursively (for output filtering).
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for writing,
	- DK4_E_WRITE_FAILED<br>
	  if writing one ore multiple bytes to the stream failed,
	- DK4_E_FLUSH_FAILED<br>
	  if flushing data downwards failed.
*/
int
dk4stream_flush_write(dk4_stream_t *strm, int flfl, dk4_er_t *erp);

/**	Flush stream input data (discard data in input buffer).
	@param	strm	Stream to flush.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for writing.
*/
int
dk4stream_flush_read(dk4_stream_t *strm, dk4_er_t *erp);

/**	Read a single character.
	@param	dst	Pointer to variable for result.
	@param	strm	Stream to read from.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for reading,
*/
int
dk4stream_c8_read_byte(char *dst, dk4_stream_t *strm, dk4_er_t *erp);

/**	Read multiple bytes into buffer.
	@param	b	Pointer to buffer start address.
	@param	szptr	Pointer to size variable, in: available size,
			out: number of bytes read.
	@param	strm	Stream to read from.
	@param	erp	Error report, may be NULL.
	@return	1 on success (there were bytes read), 0 on error.
	
	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if strm is NULL or not opened for reading,
	- DK4_E_NOT_FOUND<br>
	  if end of input was detected in read attempt,
	- DK4_E_READ_FAILED<br>
	  if a read attempt failed for other reasons.
*/
int
dk4stream_read(void *b, size_t *szptr, dk4_stream_t *strm, dk4_er_t *erp);

/**	Get number of bytes written.
	@param	strm	Stream to get number of bytes for.
	@return	Number of bytes written to the stream (number of bytes
	received from the upside, not number of bytes written
	downwards).
*/
dk4_um_t
dk4stream_bytes_written(const dk4_stream_t *strm);

/**	Check for numeric overflow in number of bytes written.
	@param	strm	Stream to check.
	@return	1 if overflow occured, 0 if there was no overflow.
*/
int
dk4stream_overflow_bytes_written(const dk4_stream_t *strm);

/**	Check whether end of input was found during read attempt.
	@param	strm	Stream to check.
	@return	1 if EOF was detected, 0 otherwise.
*/
int
dk4stream_found_eof(const dk4_stream_t *strm);

#ifdef __cplusplus
}
#endif



/**	Flags whether read or write operations allowed.
*/
enum {
  DK4_STREAM_READ	= 1,	/**< Reading from stream allowed. */
  DK4_STREAM_WRITE	= 2	/**< Writing to stream allowed. */
};



/**	Low level commands to execute in the stream API function.
	The api.cmd is set to one of the values.
	Depending on api.cmd, other api attributes must be set
	on input or must be set as response by the low level function.
*/
enum {
				/**	Read data.
  					Input	api.d:	    Low level data.
					Input	api.b:	    Input data buffer.
					Input	api.sz_in:  Input data buffer
							    size.
					Output	api.res:    1=any bytes found,
							    0=no bytes found.
					Output	api.sz_out: Number of bytes
							    read into input
							    buffer.
				*/
  DK4_STREAM_API_READ = 1,

				/**	Write data.
					Input 	api.d:	    Low level data.
					Input 	api.b:	    Output data buffer.
					Input 	api.sz_in:  Output data buffer
							    size.
					Output	api.res:    1=all bytes
							    written,
							    0=not all bytes
							    written.
					Output	api.sz_out: Number of bytes
							    written.
				*/
  DK4_STREAM_API_WRITE ,

				/**	Flush data.
					Input	api.d:	 Low level data.
					Output	api.res: 1=no error reported,
							 0=error reported.
				*/
  DK4_STREAM_API_FLUSH ,

				/**	Check whether end of input is found.
  					Input	api.d:	 Low level data.
					Output	api.res	 1=end of input
							 reached,
							 0=not yet reached.
				*/
  DK4_STREAM_API_AT_END ,

				/**	Close low level data.
					Input	api.d:	 Low level data.
					Output	api.res: 1=no error reported,
							 0=error reported.
				*/
  DK4_STREAM_API_CLOSE ,

				/**	Check whether a read result of 0
					indicates EOF.
					Input	api.d:	Low level data.
					Output	api.res	1=reading zero bytes
							indicates EOF, 0=no.
				*/
  DK4_STREAM_API_ZERO_READ_IS_EOF
};

%%	module



#include "dk4strm.h"
#include "dk4mem.h"
#include "dk4enc.h"
#include "dk4numco.h"



$!trace-include




static
void
dk4stream_api_init(dk4_stream_api_t *ptr)
{
  $? "+ dk4stream_api_init"
  DK4_MEMRES(ptr, sizeof(dk4_stream_api_t));
  ptr->d = NULL;
  ptr->b = NULL;
  ptr->sz_in = 0;
  ptr->sz_out = 0;
  ptr->res = 0;
  ptr->cmd = 0;
  $? "- dk4stream_api_init"
}



/**	Release memory allocated by a stream.
	@param	strm	Stream to release.
*/
static
void
dk4stream_release_memory(dk4_stream_t *strm)
{
  $? "+ dk4stream_release_memory PTR=%d", TR_IPTR(strm)
  if (NULL != strm) {
    dk4mem_release(strm->bi);
    dk4mem_release(strm->bo);
    strm->d = NULL;
    strm->fct = NULL;
    strm->bwr = (dk4_um_t)0UL;
    strm->szbi = 0;
    strm->szbo = 0;
    strm->usbi = 0;
    strm->usbo = 0;
    strm->rebi = 0;
    strm->fl = 0;
    strm->feoi = 0;
    strm->bwo = 0;
    dk4mem_free(strm);
  } $? "- dk4stream_release_memory"
}




/**	Flush write buffer.
*/
static
int
dk4stream_i_flush_write(dk4_stream_t *strm, int flfl, dk4_er_t *erp)
{
  dk4_stream_api_t	api;
  int		 	back	=	1;
  $? "+ dk4stream_i_flush_write"
  /*	Write buffer contents (if any) downwards.
  */
  if (0 != strm->usbo) {		$? ". bytes in output buffer"
    dk4stream_api_init(&api);
    api.cmd   = DK4_STREAM_API_WRITE;
    api.d     = strm->d;
    api.b     = strm->bo;
    api.sz_in = strm->usbo;
    (*(strm->fct))(&api);
    if (0 == api.res) {
      back = 0;
      dk4error_set_simple_error_code(erp, DK4_E_WRITE_FAILED);
    }
  }
  /*	Flush downwards.
  */
  if (0 < flfl) {			$? ". downward flush"
    dk4stream_api_init(&api);
    api.cmd = DK4_STREAM_API_FLUSH;
    api.d   = strm->d;
    (*(strm->fct))(&api);
    if (0 == api.res) {
      back = 0;
      dk4error_set_simple_error_code(erp, DK4_E_FLUSH_FAILED);
    }
  }
  /*	Indicate output buffer is empty.
  */
  strm->usbo = 0;
  $? "- dk4stream_i_flush_write %d", back
  return back;
}



/**	Internal function to write one character after checking stream.
	@param	strm	Stream to write to.
	@param	c	Character to write.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
*/
static
int
dk4stream_i_write_byte(dk4_stream_t *strm, char c, dk4_er_t *erp)
{
  int		 back	=	0;
  $? "+ dk4stream_i_write_byte"
  if (strm->usbo < strm->szbo) {
    (strm->bo)[strm->usbo] = c;
    strm->usbo += 1;
    strm->bwr += (dk4_um_t)1UL;
    if ((dk4_um_t)0UL == strm->bwr) { strm->bwo = 1; }
    back = 1;
    if (strm->usbo >= strm->szbo) {
      back = dk4stream_i_flush_write(strm, 0, erp);
    }
  } $? "- dk4stream_i_write_byte %d", back
  return back;
}




/**	Internal function to read a single character.
	@param	dst	Pointer to variable for result.
	@param	strm	Stream to read from.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error.
*/
static
int
dk4stream_i_c8_read_byte(char *dst, dk4_stream_t *strm, dk4_er_t *erp)
{
  dk4_stream_api_t	api;
  int		 	back	=	0;
  $? "+ dk4stream_i_c8_read_byte"
  if ((0 == strm->feoi) && ((strm->usbi == 0) || (strm->rebi >= strm->usbi))) {
    $? ". low level read required"
    dk4stream_api_init(&api);
    api.cmd   = DK4_STREAM_API_READ;
    api.d     = strm->d;
    api.b     = strm->bi;
    api.sz_in = strm->szbi;
    (*(strm->fct))(&api);
    if (0 != api.res) {			$? ". low level read succeeded"
      strm->rebi = 0;
      strm->usbi = api.sz_out;
      if (api.sz_out < strm->szbi) {	$? ". less bytes than buffer size"
        if (0 == strm->zreof) {
          dk4stream_api_init(&api);
	  api.cmd = DK4_STREAM_API_AT_END;
	  api.d   = strm->d;
	  (*(strm->fct))(&api);
	  if (0 != api.res) {		$? ". EOF found"
	    strm->feoi = 1;
	  }
	}
      }
    } else {				$? ". low level read failed"
      if (0 != strm->zreof) {
        strm->feoi = 1;
      } else {
        dk4stream_api_init(&api);
        api.cmd = DK4_STREAM_API_AT_END;
        api.d   = strm->d;
        (*(strm->fct))(&api);
        if (0 != api.res) {		$? ". end of input reached"
          strm->feoi = 1;
        }
      }
    }
  } else {		$? ". data in buffer available"
  }
  if ((0 < strm->usbi) && (strm->rebi < strm->usbi)) {
    $? ". data in buffer available"
    *dst = (strm->bi)[strm->rebi];
    strm->rebi += 1;
    back = 1;
  } else {		$? ". no data in buffer"
  }
  $? "- dk4stream_i_c8_read_byte %d", back
  return back;
}




dk4_stream_t *
dk4stream_open(
  void			*obj,
  dk4_stream_api_fct_t	*fct,
  int			 fl,
  size_t		 ibs,
  size_t		 obs,
  dk4_er_t		*erp
)
{
  dk4_stream_api_t	 api;
  dk4_stream_t		*back	=	NULL;
  $? "+ dk4stream_open"
  /*	Check arguments
  */
  if ((NULL == obj) || (NULL == fct)) {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    goto finished;
  }
  /*	Check flag, at least read or write must be set
  */
  if (0 == (fl & (DK4_STREAM_READ | DK4_STREAM_WRITE))) {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    goto finished;
  }
  /*	Allocate memory for stream itself
  */
  back = dk4mem_new(dk4_stream_t,1,erp);
  if (NULL == back) {
    goto finished;
  }
  /*	Initialize members
  */
  back->d = obj; back->fct = fct;
  back->bi = NULL; back->bo = NULL;
  back->bwr = (dk4_um_t)0UL;
  back->szbi = 0; back->szbo = 0;
  back->usbi = 0; back->usbo = 0; back->rebi = 0;
  back->fl = fl; back->feoi = 0;
  back->bwo = 0;
  back->oenc = DK4_FILE_ENCODING_ASCII;
  back->zreof = 0;
  /*	Allocate input buffer or destroy object
  */
  if (fl & DK4_STREAM_READ) {
    back->szbi = ((0 < ibs) ? ibs : 4096);
    back->bi = dk4mem_new(char,back->szbi,erp);
    if (NULL == back->bi) {
      dk4stream_release_memory(back);
      back = NULL;
      goto finished;
    }
  }
  /*	Allocate output buffer or destroy object
  */
  if (fl & DK4_STREAM_WRITE) {
    back->szbo = ((0 < obs) ? obs : 4096);
    back->bo = dk4mem_new(char,back->szbo,erp);
    if (NULL == back->bo) {
      dk4stream_release_memory(back);
      back = NULL;
      goto finished;
    }
  }
  /*	Check whether reading zero bytes indicates end of input
  */
  dk4stream_api_init(&api);
  api.cmd = DK4_STREAM_API_ZERO_READ_IS_EOF;
  api.d   = obj;
  (*(back->fct))(&api);
  if (0 != api.res) { back->zreof = 1; }
finished:
  $? "- dk4stream_open PTR=%d", TR_IPTR(back)
  return back;
}



int
dk4stream_close(dk4_stream_t *strm, dk4_er_t *erp)
{
  dk4_stream_api_t	api;
  int		 	back	=	0;
  $? "+ dk4stream_close"
  /*	Check argument.
  */
  if (NULL == strm) {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    goto finished;
  }

  /*	Success so far, unless there are errors in the next sections.
  */
  back = 1;

  /*	Write bytes in output buffer downwards.
  */
  if ((strm->fl) & DK4_STREAM_WRITE) {
    dk4stream_api_init(&api);
    api.cmd   = DK4_STREAM_API_WRITE;
    api.d     = strm->d;
    api.b     = strm->bo;
    api.sz_in = strm->usbo;
    (*(strm->fct))(&api);
    if (0 == api.res) {
      back = 0;
      dk4error_set_simple_error_code(erp, DK4_E_WRITE_FAILED);
    }
  }

  /*	Attempt to flush downwards.
  */
  if ((strm->fl) & DK4_STREAM_WRITE) {
    dk4stream_api_init(&api);
    api.cmd = DK4_STREAM_API_FLUSH;
    api.d   = strm->d;
    (*(strm->fct))(&api);
    if (0 == api.res) {
      back = 0;
      dk4error_set_simple_error_code(erp, DK4_E_FLUSH_FAILED);
    }
  }

  /*	Finalize downward data structures.
  */
  dk4stream_api_init(&api);
  api.cmd = DK4_STREAM_API_CLOSE;
  api.d   = strm->d;
  (*(strm->fct))(&api);
  if (0 == api.res) {
    back = 0;
    dk4error_set_simple_error_code(erp, DK4_E_CLOSE_FAILED);
  }

  /*	Release memory.
  */
  dk4stream_release_memory(strm);

finished:
  $? "- dk4stream_close %d", back
  return back;
}



int
dk4stream_write_byte(dk4_stream_t *strm, char c, dk4_er_t *erp)
{
  int		 back	=	0;
  $? "+ dk4stream_write_byte"
  if (NULL != strm) {
    if ((strm->fl) & DK4_STREAM_WRITE) {
      back = dk4stream_i_write_byte(strm, c, erp);
    } else {
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_write_byte %d", back
  return back;
}



#if	NOT_OPTIMIZED

int
dk4stream_write(dk4_stream_t *strm, const void *b, size_t sz, dk4_er_t *erp)
{
  char		*cptr;			/* Traverse buffer */
  int		 back	=	0;
  $? "+ dk4stream_write"
  if ((NULL != strm) && (NULL != b) && (0 < sz)) {
    if ((strm->fl) & DK4_STREAM_WRITE) {
      back = 1;
      cptr = (char *)b;
      while(sz--) {
        if (0 == dk4stream_i_write_byte(strm, *(cptr++), erp)) {
	  back = 0;
	}
      }
    } else {
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_write %d", back
  return back;
}

#else

int
dk4stream_write(dk4_stream_t *strm, const void *b, size_t sz, dk4_er_t *erp)
{
  char		*cptr;			/* Traverse buffer */
  size_t	 bc;
  int		 back	=	0;
  int		 cc;

  $? "+ dk4stream_write %lu", (unsigned long)sz
  if ((NULL != strm) && (NULL != b) && (0 < sz)) {
    if ((strm->fl) & DK4_STREAM_WRITE) {
      back = 1;
      cptr = (char *)b;
      do {
        cc = 0;					$? ". loop start"
        if (0 < sz) {
	  if (strm->usbo < strm->szbo) {	$? ". can copy"
	    /* Attempt to copy as many bytes as still free in output buffer */
	    bc = strm->szbo - strm->usbo; $? ". bc = %lu", (unsigned long)bc
	    /* If not enough bytes available, correct number of bytes */
	    if (bc > sz) { bc = sz; }	  $? ". bc = %lu", (unsigned long)bc
	    DK4_MEMCPY(&((strm->bo)[strm->usbo]), cptr, bc);
	    strm->usbo	+= bc;		$? ". usbo = %lu", (unsigned long)(strm->usbo)
	    cptr	=  &(cptr[bc]);
	    sz		-= bc;		$? ". sz   = %lu", (unsigned long)sz
	    if ((DK4_UM_MAX - (dk4_um_t)bc) < strm->bwr) {
	      strm->bwo = 1;			$? "! numeric overflow"
	      back	= 0;
	    }
	    strm->bwr   += (dk4_um_t)bc; $? ". bwr = %lu", (unsigned long)(strm->bwr)
	    if (strm->usbo >= strm->szbo) {	$? ". must flush"
	      if (0 == dk4stream_i_flush_write(strm, 0, erp)) {
	        back = 0;			$? "! flush failed"
	      }
	    }
	    if (0 < sz) { cc = 1; }
	  } else {				$? ". must flush first"
	    if (0 == dk4stream_i_flush_write(strm, 0, erp)) {
	      back = 0;				$? "! flush failed"
	    }
	  }
	}
      } while(0 != cc);
    } else {					$? "! stream not writable"
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {					$? "! invalid args"
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_write %d", back
  return back;
}

#endif



int
dk4stream_write_char_string(dk4_stream_t *strm, const char *str, dk4_er_t *erp)
{
  size_t	sl;
  int		back	= 0;
  if ((NULL != strm) && (NULL != str)) {
    sl = strlen(str);
    back = dk4stream_write(strm, str, sl, erp);
  }
  else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}



int
dk4stream_flush_read(dk4_stream_t *strm, dk4_er_t *erp)
{
  int back = 0;
  $? "+ dk4stream_flush_read"
  if (NULL != strm) {
    if ((strm->fl) & DK4_STREAM_READ) {
      back = 1;
      strm->usbi = 0;
      strm->rebi = 0;
    } else {
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_flush_read %d", back
  return back;
}



int
dk4stream_flush_write(dk4_stream_t *strm, int flfl, dk4_er_t *erp)
{
  int back = 0;
  $? "+ dk4stream_flush_write"
  if (NULL != strm) {
    if ((strm->fl) & DK4_STREAM_WRITE) {
      back = dk4stream_i_flush_write(strm, flfl, erp);
    } else {
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_flush_write %d", back
  return back;
}



int
dk4stream_flush(dk4_stream_t *strm, int flfl, dk4_er_t *erp)
{
  int		 back	=	0;
  $? "+ dk4stream_flush"
  if (NULL != strm) {
    back = 1;
    if ((strm->fl) & DK4_STREAM_WRITE) {
      if (0 == dk4stream_flush_write(strm, flfl, erp)) {
        back = 0;
      }
    }
    if ((strm->fl) & DK4_STREAM_READ) {
      if (0 == dk4stream_flush_read(strm, erp)) {
        back = 0;
      }
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_flush %d", back
  return back;
}



int
dk4stream_c8_read_byte(char *dst, dk4_stream_t *strm, dk4_er_t *erp)
{
  int		 back = 0;
  $? "+ dk4stream_c8_read_byte"
  if ((NULL != dst) && (NULL != strm)) {	$? ". pointers ok"
    if ((strm->fl) & DK4_STREAM_READ) {		$? ". read"
      back = dk4stream_i_c8_read_byte(dst, strm, erp);
    } else {
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_c8_read_byte %d", back
  return back;
}



int
dk4stream_read(void *b, size_t *szptr, dk4_stream_t *strm, dk4_er_t *erp)
{
  char		*cptr;			/* Traverse the buffer */
  size_t	 szin;			/* Input: Available buffer size */
  size_t	 szout;			/* Output: Used buffer size */
  int		 back	=	0;	/* Function result */
  int		 cc	=	1;	/* Flag: Can continue */
  $? "+ dk4stream_read"
  if ((NULL != b) && (NULL != szptr) && (NULL != strm)) {
    if (((strm->fl) & DK4_STREAM_READ) && (0 < *szptr)) {
      szin = *szptr; szout = 0;
      cptr = (char *)b;
      do {
        if (0 != dk4stream_i_c8_read_byte(cptr++, strm, erp)) {
	  szout++;
	  if (szout >= szin) {
	    cc = 0;
	    back = 1;
	  }
	} else {
	  cc = 0;
	  if (0 < szout) {
	    back = 1;
	  } else {
	    if (0 != dk4stream_found_eof(strm)) {
	      dk4error_set_simple_error_code(erp, DK4_E_NOT_FOUND);
	    } else {
	      dk4error_set_simple_error_code(erp, DK4_E_READ_FAILED);
	    }
	  }
	}
      } while (0 != cc);
      *szptr = szout;
    } else {
      dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  } $? "- dk4stream_read %d", back
  return back;
}



dk4_um_t
dk4stream_bytes_written(const dk4_stream_t *strm)
{
  dk4_um_t	back	=	(dk4_um_t)0UL;
  if (NULL != strm) { back = strm->bwr; }
  return back;
}



int
dk4stream_overflow_bytes_written(const dk4_stream_t *strm)
{
  int back = 0;
  if (NULL != strm) { back = strm->bwo; }
  return back;
}



int
dk4stream_found_eof(const dk4_stream_t *strm)
{
  int back = 0;
  if (NULL != strm) {
    back = strm->feoi;
  }
  return back;
}