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/****************************************************************************
* libc/msic/lib_kbddecode.c
* Decoding side of the Keyboard CODEC
*
* Copyright (C) 2012 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 <assert.h>
#include <debug.h>
#include <nuttx/streams.h>
#include <nuttx/ascii.h>
#include <nuttx/input/kbd_codec.h>
/****************************************************************************
* Pre-Processor Definitions
****************************************************************************/
#define NDX_ESC 0
#define NDX_BRACKET 1
#define NDX_CODE 2
#define NDX_TERMINATOR 3
#define NCH_ESC 1
#define NCH_BRACKET 2
#define NCH_CODE 3
#define NCH_TERMINATOR 4
#define TERM_MIN ('a' + KBD_RELEASE)
#define TERM_MAX ('a' + KBD_SPECREL)
#define TERM_RETURN(a) ((a) - 'a')
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: kbd_reget
*
* Description:
* We have unused characters from the last, unsuccessful. Return one of
* these instead of the .
*
* 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
* kbd_keycode_e
*
* Returned Value:
* KBD_PRESS - Indicates the successful receipt of norma keyboard data.
*
****************************************************************************/
static int kbd_reget(FAR struct kbd_getstate_s *state, FAR uint8_t *pch)
{
/* Return the next character */
*pch = state->buf[state->ndx];
state->ndx++;
state->nch--;
return KBD_PRESS;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: kbd_decode
*
* Description:
* Get one byte of data or special command from the driver provided input
* buffer.
*
* Input Parameters:
* stream - An instance of lib_instream_s to do the low-level get
* operation.
* pch - The location to save the returned value. This may be
* either a normal, character code or a special command from enum
* kbd_keycode_e
* state - A user provided buffer to support parsing. This structure
* should be cleared the first time that kbd_decode is called.
*
* Returned Value:
*
* KBD_PRESS - Indicates the successful receipt of normal, keyboard data.
* This corresponds to a keypress event. The returned value in pch is a
* simple byte of text or control data corresponding to the pressed key.
* KBD_RELEASE - Indicates a key release event. The returned value in pch
* is the byte of text or control data corresponding to the released key.
* KBD_SPECPRESS - Indicates the successful receipt of a special keyboard
* command. The returned value in pch is a value from enum kbd_getstate_s.
* KBD_SPECREL - Indicates a special key release event. The returned value
* in pch is a value from enum kbd_getstate_s.
* EOF - An error has getting the next character (reported by the stream).
* Normally indicates the end of file.
*
****************************************************************************/
int kbd_decode(FAR struct lib_instream_s *stream,
FAR struct kbd_getstate_s *state, FAR uint8_t *pch)
{
int ch;
DEBUGASSERT(stream && state && pch);
/* Are their ungotten characters from the last, failed parse? */
if (state->nch > 0)
{
/* Yes, return the next ungotten character */
return kbd_reget(state, pch);
}
state->ndx = 0;
/* No, ungotten characters. Check for the beginning of an ESC sequence. */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream */
return KBD_ERROR;
}
else
{
state->buf[NDX_ESC] = (uint8_t)ch;
state->nch = NCH_ESC;
if (ch != ASCII_ESC)
{
/* Not the beginning of an escape sequence. Return the character. */
return kbd_reget(state, pch);
}
}
/* Check for ESC-[ */
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 kbd_reget(state, pch);
}
else
{
state->buf[NDX_BRACKET] = ch;
state->nch = NCH_BRACKET;
if (ch != '[')
{
/* Not the beginning of an escape sequence. Return the ESC now,
* return the following character later.
*/
return kbd_reget(state, pch);
}
}
/* Get and verify the special keyboard data to decode */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream. Unget everything and return the ESC character.
*/
return kbd_reget(state, pch);
}
else
{
state->buf[NDX_CODE] = (uint8_t)ch;
state->nch = NCH_CODE;
/* Check for a valid special command code */
if (ch < FIRST_KEYCODE || ch > LAST_KEYCODE)
{
/* Not a special command code, return the ESC now and the next two
* characters later.
*/
return kbd_reget(state, pch);
}
}
/* Check for the final semicolon */
ch = stream->get(stream);
if (ch == EOF)
{
/* End of file/stream. Unget everything and return the ESC character.
*/
return kbd_reget(state, pch);
}
else
{
state->buf[NDX_TERMINATOR] = (uint8_t)ch;
state->nch = NCH_TERMINATOR;
/* Check for a valid special command code */
if (ch < TERM_MIN || ch > TERM_MAX)
{
/* Not a special command code, return the ESC now and the next two
* characters later.
*/
return kbd_reget(state, pch);
}
}
/* We have successfully parsed the the entire escape sequence. Return the
* keyboard value in pch and the value an indication determined by the
* terminating character.
*/
*pch = state->buf[NDX_CODE];
state->nch = 0;
return TERM_RETURN(state->buf[NDX_TERMINATOR]);
}
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