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incubator-nuttx/drivers/syslog/syslog_intbuffer.c

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/****************************************************************************
* drivers/syslog/syslog_intbuffer.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/syslog/syslog.h>
#include <nuttx/irq.h>
#include "syslog.h"
#ifdef CONFIG_SYSLOG_INTBUFFER
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#if CONFIG_SYSLOG_INTBUFSIZE > 65535
# undef CONFIG_SYSLOG_INTBUFSIZE
# define CONFIG_SYSLOG_INTBUFSIZE 65535
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure encapsulates the interrupt buffer state */
struct g_syslog_intbuffer_s
{
volatile uint16_t si_inndx;
volatile uint16_t si_outndx;
uint8_t si_buffer[CONFIG_SYSLOG_INTBUFSIZE];
};
/****************************************************************************
* Private Data
****************************************************************************/
static struct g_syslog_intbuffer_s g_syslog_intbuffer;
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Name: syslog_remove_intbuffer
*
* Description:
* Extract any characters that may have been added to the interrupt buffer
* to the SYSLOG device.
*
* Input Parameters:
* None
*
* Returned Value:
* On success, the extracted character is returned. EOF is returned if
* the interrupt buffer is empty.
*
* Assumptions:
* Interrupts may or may not be disabled.
*
****************************************************************************/
int syslog_remove_intbuffer(void)
{
irqstate_t flags;
uint32_t outndx;
int ret = EOF;
/* Extraction of the character and adjustment of the circular buffer
* indices must be performed in a critical section to protect from
* concurrent modification from interrupt handlers.
*/
flags = enter_critical_section();
/* Check if the interrupt buffer is empty */
outndx = (uint32_t)g_syslog_intbuffer.si_outndx;
if (outndx != (uint32_t)g_syslog_intbuffer.si_inndx)
{
/* Not empty.. Take the next character from the interrupt buffer */
ret = g_syslog_intbuffer.si_buffer[outndx];
/* Increment the OUT index, handling wrap-around */
if (++outndx >= CONFIG_SYSLOG_INTBUFSIZE)
{
outndx -= CONFIG_SYSLOG_INTBUFSIZE;
}
g_syslog_intbuffer.si_outndx = (uint16_t)outndx;
}
leave_critical_section(flags);
/* Now we can send the extracted character to the SYSLOG device */
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: syslog_add_intbuffer
*
* Description:
* Add one more character to the interrupt buffer. In the event of
* buffer overflowed, the character will be dropped. The indication
* "[truncated]\n" will be appended to the end of the interrupt buffer.
*
* Input Parameters:
* ch - The character to add to the interrupt buffer (must be positive).
*
* Returned Value:
* Zero success, the character is echoed back to the caller. A negated
* errno value is returned on any failure.
*
* Assumptions:
* - Called either from (1) interrupt handling logic with interrupts
* disabled or from an IDLE thread with interrupts enabled.
* - Requires caution because there may be an interrupted execution of
* syslog_flush_intbuffer(): Only the outndx can be modified.
*
****************************************************************************/
int syslog_add_intbuffer(int ch)
{
irqstate_t flags;
uint32_t inndx;
uint32_t outndx;
uint32_t endndx;
unsigned int inuse;
int ret = OK;
int i;
/* Disable concurrent modification from interrupt handling logic */
flags = enter_critical_section();
/* How much space is left in the intbuffer? */
inndx = (uint32_t)g_syslog_intbuffer.si_inndx;
outndx = (uint32_t)g_syslog_intbuffer.si_outndx;
endndx = inndx;
if (endndx < outndx)
{
endndx += CONFIG_SYSLOG_INTBUFSIZE;
}
inuse = (unsigned int)(endndx - outndx);
/* Is there space for another character */
if (inuse == CONFIG_SYSLOG_INTBUFSIZE - 1)
{
int oldch = syslog_remove_intbuffer();
for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
{
if (g_syslog_channel[i] == NULL)
{
break;
}
#ifdef CONFIG_SYSLOG_IOCTL
if (g_syslog_channel[i]->sc_disable)
{
continue;
}
#endif
/* Select which putc function to use for this flush */
if (g_syslog_channel[i]->sc_ops->sc_force)
{
g_syslog_channel[i]->sc_ops->sc_force(
g_syslog_channel[i], oldch);
}
}
ret = -ENOSPC;
}
/* Copy one character */
g_syslog_intbuffer.si_buffer[inndx] = (uint8_t)ch;
/* Increment the IN index, handling wrap-around */
if (++inndx >= CONFIG_SYSLOG_INTBUFSIZE)
{
inndx -= CONFIG_SYSLOG_INTBUFSIZE;
}
g_syslog_intbuffer.si_inndx = (uint16_t)inndx;
leave_critical_section(flags);
return ret;
}
/****************************************************************************
* Name: syslog_flush_intbuffer
*
* Description:
* Flush any characters that may have been added to the interrupt buffer
* to the SYSLOG device.
*
* Input Parameters:
* force - Use the force() method of the channel vs. the putc() method.
*
* Returned Value:
* On success, the character is echoed back to the caller. A negated
* errno value is returned on any failure.
*
* Assumptions:
* Interrupts may or may not be disabled.
*
****************************************************************************/
int syslog_flush_intbuffer(bool force)
{
syslog_putc_t putfunc;
irqstate_t flags;
int ch;
int i;
/* This logic is performed with the scheduler disabled to protect from
* concurrent modification by other tasks.
*/
flags = enter_critical_section();
do
{
/* Transfer one character to time. This is inefficient, but is
* done in this way to: (1) Deal with concurrent modification of
* the interrupt buffer from interrupt activity, (2) Avoid keeper
* interrupts disabled for a long time, and (3) to handler
* wrap-around of the circular buffer indices.
*/
ch = syslog_remove_intbuffer();
for (i = 0; i < CONFIG_SYSLOG_MAX_CHANNELS; i++)
{
if ((g_syslog_channel[i] == NULL) || (ch == EOF))
{
break;
}
#ifdef CONFIG_SYSLOG_IOCTL
if (g_syslog_channel[i]->sc_disable)
{
continue;
}
#endif
/* Select which putc function to use for this flush */
putfunc = force ? g_syslog_channel[i]->sc_ops->sc_force :
g_syslog_channel[i]->sc_ops->sc_putc;
putfunc(g_syslog_channel[i], ch);
}
}
while (ch != EOF);
leave_critical_section(flags);
return ch;
}
#endif /* CONFIG_SYSLOG_INTBUFFER */
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