%%	options

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



%%	header

/**	@file	dk4ahd.h	ASCIIHex decoder.

First initialize the decoder using the dk4ahex_dec_init() function.

Add text characters using the dk4ahex_dec_add() function.
The function returns DK4_EDSTM_ACCEPT if the text character was successfully
stored in the decoder without completing a byte.
The DK4_EDSTM_FINISHED return code indicates that a byte was finished, use
dk4ahex_output() to retrieve it.
The DK4_EDSTM_STOP return code indicates that an end of data (EOD) marker
was found.

After feeding all text characters into the decoder use dk4ahex_finish()
to check whether there is an unprocessed half-byte stored.
If the function returns DK4_EDSTM_FINISHED, use dk4ahex_output() to
retrieve the final byte.

Note: The call to dk4ahex_finish() is also necessary after
obtaining DK4_EDSTM_STOP from dk4ahex_dec_add().

*/

#include "dk4conf.h"
#include "dk4error.h"

/**	ASCII-Hex decoder.
*/
typedef struct {
  int			cpos;	/**< Current position. */
  unsigned char		obyte;	/**< Output byte. */
} dk4_ahex_dec_t;

#ifdef __cplusplus
extern "C" {
#endif

/**	Initialize decoder.
	@param	dec	Decoder to initialize.
	@param	erp	Error report, may be NULL.
*/
void
dk4ahex_dec_init(dk4_ahex_dec_t *dec, dk4_er_t *erp);

/**	Add text character to decoder.
	@param	dec	Decoder.
	@param	tc	Text character to add.
	@param	erp	Error report, may be NULL.
	@return	Action to take:
	- DK4_EDSTM_ACCEPT<br>
	  if the text was saved in the decoder, no action necessary.
	- DK4_EDSTM_FINISHED<br>
	  if a byte was completed, use dk4ahex_dec_output() to retrieve
	  the byte.
	- DK4_EDSTM_STOP<br>
	  if the end of data (EOD) marker was detected.
	  Use dk4ahex_finish() to check whether there is still data
	  in the decoder.
	- DK4_EDSTM_ERROR<br>
	  if an error occured.
*/
int
dk4ahex_dec_add(dk4_ahex_dec_t *dec, char tc, dk4_er_t *erp);

/**	Check for final byte.
	@param	dec	Decoder.
	@param	erp	Error report, may be NULL.
	@return	Action to take, one from:
	- DK4_EDSTM_ACCEPT<br>
	  if there is no action necessary.
	- DK4_EDSTM_FINISHED<br>
	  if there is data available, use dk4ahex_dec_output() to retrieve
	  the byte.
	- DK4_EDSTM_ERROR<br>
	  if an error occured.
*/
int
dk4ahex_finish(dk4_ahex_dec_t *dec, dk4_er_t *erp);

/**	Retrieve current decoder content.
	@param	dec	Decoder.
	@param	erp	Error report, may be NULL.
	@return	The current byte stored in the decoder.
*/
unsigned char
dk4ahex_output(dk4_ahex_dec_t *dec, dk4_er_t *erp);

#ifdef __cplusplus
}
#endif

%%	module


#include "dk4ahd.h"
#include "dk4mem.h"
#include "dk4edstm.h"



$!trace-include



void
dk4ahex_dec_init(dk4_ahex_dec_t *dec, dk4_er_t *erp)
{
  if (NULL != dec) {
    DK4_MEMRES(dec, sizeof(dk4_ahex_dec_t));
    dec->cpos =  0;
    dec->obyte = 0x00;
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
}



int
dk4ahex_dec_add(dk4_ahex_dec_t *dec, char tc, dk4_er_t *erp)
{
  int		 back = DK4_EDSTM_ERROR;
  if (NULL != dec) {
    switch (tc) {
      case ' ' : case '\t' : case '\r' : case '\n' : case 0x00 : case 0x0C : {
        back = DK4_EDSTM_ACCEPT;
      } break;
      case '>' : {
        back = DK4_EDSTM_STOP;
      } break;
      case '0' : {
        if (0 != dec->cpos) {
          dec->cpos  = 2;
	} else {
	  dec->obyte = 0x00;
	  dec->cpos  = 1;
	}
      } break;
      case '1' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x01; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x10; dec->cpos  = 1;
	}
      } break;
      case '2' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x02; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x20; dec->cpos  = 1;
	}
      } break;
      case '3' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x03; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x30; dec->cpos  = 1;
	}
      } break;
      case '4' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x04; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x40; dec->cpos  = 1;
	}
      } break;
      case '5' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x05; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x50; dec->cpos  = 1;
	}
      } break;
      case '6' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x06; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x60; dec->cpos  = 1;
	}
      } break;
      case '7' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x07; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x70; dec->cpos  = 1;
	}
      } break;
      case '8' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x08; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x80; dec->cpos  = 1;
	}
      } break;
      case '9' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x09; dec->cpos  = 2;
	} else {
	  dec->obyte = 0x90; dec->cpos  = 1;
	}
      } break;
      case 'a' : case 'A' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x0A; dec->cpos  = 2;
	} else {
	  dec->obyte = 0xA0; dec->cpos  = 1;
	}
      } break;
      case 'b' : case 'B' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x0B; dec->cpos  = 2;
	} else {
	  dec->obyte = 0xB0; dec->cpos  = 1;
	}
      } break;
      case 'c' : case 'C' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x0C; dec->cpos  = 2;
	} else {
	  dec->obyte = 0xC0; dec->cpos  = 1;
	}
      } break;
      case 'd' : case 'D' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x0D; dec->cpos  = 2;
	} else {
	  dec->obyte = 0xD0; dec->cpos  = 1;
	}
      } break;
      case 'e' : case 'E' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x0E; dec->cpos  = 2;
	} else {
	  dec->obyte = 0xE0; dec->cpos  = 1;
	}
      } break;
      case 'f' : case 'F' : {
        if (0 != dec->cpos) {
	  dec->obyte |= 0x0F; dec->cpos  = 2;
	} else {
	  dec->obyte = 0xF0; dec->cpos  = 1;
	}
      } break;
    }
    if (2 == dec->cpos) {
      dec->cpos = 0;
      back = DK4_EDSTM_FINISHED;
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}



int
dk4ahex_finish(dk4_ahex_dec_t *dec, dk4_er_t *erp)
{
  int		 back	=	DK4_EDSTM_ERROR;
  if (NULL != dec) {
    switch (dec->cpos) {
      case 1: {
        back = DK4_EDSTM_FINISHED;
      } break;
      default : {
        back = DK4_EDSTM_ACCEPT;
      } break;
    }
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}



unsigned char
dk4ahex_output(dk4_ahex_dec_t *dec, dk4_er_t *erp)
{
  unsigned char back	= 0x00;
  if (NULL != dec) {
    back = dec->obyte;
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}