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nuttx/libc/misc/lib_slcddecode.c

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/****************************************************************************
* libc/msic/lib_slcddecode.c
* Decoding side of the SLCD CODEC
*
* Copyright (C) 2013 Gregory Nutt. All rights reserved.
* Authors: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/streams.h>
#include <nuttx/ascii.h>
#include <nuttx/lcd/slcd_codec.h>
/****************************************************************************
* Pre-Processor Definitions
****************************************************************************/
#define NDX_ESC 0
#define NDX_BRACKET 1
#define NDX_CODE3 2
#define NDX_COUNTH 2
#define NDX_COUNTL 3
#define NDX_CODE5 4
#define NCH_ESC 1
#define NCH_BRACKET 2
#define NCH_CODE3 3
#define NCH_COUNTH 3
#define NCH_COUNTL 4
#define NCH_CODE5 5
#define IS_HEX(a) ((((a) >= '0') && ((a) <= '9')) || \
(((a) >= 'a') && ((a) <= 'f')))
#define CODE_MIN ('A' + FIRST_SLCDCODE)
#define CODE_MAX ('A' + LAST_SLCDCODE)
#define IS_CODE(a) (((a) >= CODE_MIN) && ((a) <= CODE_MAX))
#define CODE_RETURN(a) (enum slcdcode_e)((a) - 'A')
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: slcd_nibble
*
* Description:
* Convert a ASCII hexadecimal character (using only lower case alphabetics
* into a binary nibble
*
* Input Parameters:
* ascii - The nibble characgter.
*
* Returned Value:
* The binary value of the nibble.
*
****************************************************************************/
static uint8_t slcd_nibble(uint8_t ascii)
{
if (ascii >= '0' && ascii <= '9')
{
return ascii - '0';
}
else
{
return ascii - 'a';
}
}
/****************************************************************************
* Name: slcd_reget
*
* Description:
* We have unused characters from the last, unsuccessful decode attempt.
* Return one of these instead of the new character from the stream.
*
* Input Parameters:
* stream - An instance of lib_instream_s to do the low-level get
* operation.
* pch - The location character to save the returned value. This may be
* either a normal, character code or a special command from enum
* slcd_keycode_e
*
* Returned Value:
* Always SLCDRET_CHAR
*
****************************************************************************/
static enum slcdret_e slcd_reget(FAR struct slcdstate_s *state,
FAR uint8_t *pch, FAR uint8_t *parg)
{
/* Return the next character */
*pch = state->buf[state->ndx];
*parg = 0;
/* Bump up the indices and return false (meaning a normal character) */
state->ndx++;
state->nch--;
return SLCDRET_CHAR;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: slcd_decode
*
* Description:
* Get one byte of data or special command from the application provided
* input buffer.
*
* Input Parameters:
* stream - An instance of lib_instream_s to do the low-level get
* operation.
* state - A user provided buffer to support parsing. This structure
* should be cleared the first time that slcd_decode is called.
* pch - The location to save the returned value. This may be
* either a normal, character code or a special command from enum
* slcdcode_e, depending on the return value from slcd_decode()
* parg - The location to save the count argument that accompanies some
* special actions
*
* Returned Value:
*
* false: Normal character
* true: Special SLCD action code with possible argument
*
****************************************************************************/
enum slcdret_e slcd_decode(FAR struct lib_instream_s *stream,
FAR struct slcdstate_s *state, FAR uint8_t *pch,
FAR uint8_t *parg)
{
enum slcdcode_e code;
uint8_t count;
int ch;
DEBUGASSERT(stream && state && pch && parg);
/* Are their ungotten characters from the last, failed parse? */
if (state->nch > 0)
{
/* Yes, return the next ungotten character */
return slcd_reget(state, pch, parg);
}
state->ndx = 0;
/* No, ungotten characters. Get the next character from the buffer. */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream (or perhaps an I/O error) */
return SLCDRET_EOF;
}
/* Save the character (whatever it is) in case we fail parsing later */
state->buf[NDX_ESC] = (uint8_t)ch;
state->nch = NCH_ESC;
/* Check for the beginning of an escape sequence */
if (ch != ASCII_ESC)
{
/* Not the beginning of an escape sequence. Return the character. */
return slcd_reget(state, pch, parg);
}
/* Get the next character from the buffer */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream. Return the escape character now. We will
* return the EOF indication next time.
*/
return slcd_reget(state, pch, parg);
}
/* Save the character (whatever it is) in case we fail parsing later */
state->buf[NDX_BRACKET] = ch;
state->nch = NCH_BRACKET;
/* Check for ESC-[ */
if (ch != '[')
{
/* Not the beginning of an escape sequence. Return the ESC now,
* return the following characters later.
*/
return slcd_reget(state, pch, parg);
}
/* Get the next character from the buffer */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream. Return the ESC now; return the following
* characters later.
*/
return slcd_reget(state, pch, parg);
}
/* If the next character is a hexidecimal value (with lower case
* alphabetic characters), then we are parsing a 5-byte sequence.
*/
if (!IS_HEX(ch))
{
/* Verify the special CLCD action code */
if (ch < (int)FIRST_SLCDCODE || ch > (int)LAST_SLCDCODE)
{
/* Not a special command code.. put the character in the reget
* buffer.
*/
state->buf[NDX_CODE3] = (uint8_t)ch;
state->nch = NCH_CODE3;
/* Return the ESC now and the next two characters later. */
return slcd_reget(state, pch, parg);
}
/* Provide the return values */
code = CODE_RETURN(ch);
count = 0;
}
else
{
/* Save the first character of the two byte hexidecimal number */
state->buf[NDX_COUNTH] = (uint8_t)ch;
state->nch = NCH_COUNTH;
/* Get the next character from the buffer */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream. Return the ESC now; return the following
* characters later.
*/
return slcd_reget(state, pch, parg);
}
/* We expect the next character to be the second byte of hexidecimal
* count value.
*/
if (!IS_HEX(ch))
{
/* Not a 5-byte escape sequence. Return the ESC now; return the
* following characters later.
*/
return slcd_reget(state, pch, parg);
}
/* Save the second character of the two byte hexidecimal number */
state->buf[NDX_COUNTL] = (uint8_t)ch;
state->nch = NCH_COUNTL;
/* Get the next character from the buffer */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream. Return the ESC now; return the following
* characters later.
*/
return slcd_reget(state, pch, parg);
}
/* Put the character in the reget buffer because there is on more way
* that we can fail.
*/
state->buf[NDX_CODE5] = (uint8_t)ch;
state->nch = NCH_CODE5;
/* Verify the special CLCD action code */
if (ch < (int)FIRST_SLCDCODE || ch > (int)LAST_SLCDCODE)
{
/* Not a special command code. Return the ESC now and the rest
* of the characters later.
*/
return slcd_reget(state, pch, parg);
}
/* Provide the return values */
code = CODE_RETURN(ch);
count = slcd_nibble(state->buf[NDX_COUNTH]) << 4;
slcd_nibble(state->buf[NDX_COUNTL]);
/* All count values must be greater than 0 or something is wrong */
if (count < 1)
{
/* Return the ESC now and the rest of the characters later. */
return slcd_reget(state, pch, parg);
}
}
/* We have successfully parsed the the entire escape sequence. Return the
* CLCD value in pch, return the count in parg, and an indication that this
* is a special action.
*/
*pch = code;
*parg = count;
state->nch = 0;
return SLCDRET_SPEC;
}
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