source: mainline/kernel/generic/src/console/console.c@ c859753

/*
 * Copyright (c) 2003 Josef Cejka
 * Copyright (c) 2005 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @addtogroup genericconsole
 * @{
 */
/** @file
 */

#include <console/console.h>
#include <console/chardev.h>
#include <synch/waitq.h>
#include <synch/spinlock.h>
#include <arch/types.h>
#include <arch.h>
#include <func.h>
#include <print.h>
#include <atomic.h>

#define KLOG_SIZE 4096

/**< Kernel log cyclic buffer */
static char klog[KLOG_SIZE];

/**< First kernel log characters */
static index_t klog_start = 0;
/**< Number of valid kernel log characters */
static size_t klog_len = 0;
/**< Number of stored (not printed) kernel log characters */
static size_t klog_stored = 0;

static chardev_operations_t null_stdout_ops = {
        .suspend = NULL,
        .resume = NULL,
        .write = NULL,
        .read = NULL
};

chardev_t null_stdout = {
        .name = "null",
        .op = &null_stdout_ops
};

/** Standard input character device. */
chardev_t *stdin = NULL;
chardev_t *stdout = &null_stdout;

/** Get character from character device. Do not echo character.
 *
 * @param chardev Character device.
 *
 * @return Character read.
 */
uint8_t _getc(chardev_t *chardev)
{
        uint8_t ch;
        ipl_t ipl;

        if (atomic_get(&haltstate)) {
                /* If we are here, we are hopefully on the processor, that 
                 * issued the 'halt' command, so proceed to read the character
                 * directly from input
                 */
                if (chardev->op->read)
                        return chardev->op->read(chardev);
                /* no other way of interacting with user, halt */
                if (CPU)
                        printf("cpu%u: ", CPU->id);
                else
                        printf("cpu: ");
                printf("halted - no kconsole\n");
                cpu_halt();
        }

        waitq_sleep(&chardev->wq);
        ipl = interrupts_disable();
        spinlock_lock(&chardev->lock);
        ch = chardev->buffer[(chardev->index - chardev->counter) % CHARDEV_BUFLEN];
        chardev->counter--;
        spinlock_unlock(&chardev->lock);
        interrupts_restore(ipl);

        chardev->op->resume(chardev);

        return ch;
}

/** Get string from character device.
 *
 * Read characters from character device until first occurrence
 * of newline character.
 *
 * @param chardev Character device.
 * @param buf Buffer where to store string terminated by '\0'.
 * @param buflen Size of the buffer.
 *
 * @return Number of characters read.
 */
count_t gets(chardev_t *chardev, char *buf, size_t buflen)
{
        index_t index = 0;
        char ch;

        while (index < buflen) {
                ch = _getc(chardev);
                if (ch == '\b') {
                        if (index > 0) {
                                index--;
                                /* Space backspace, space */
                                putchar('\b');
                                putchar(' ');
                                putchar('\b');
                        }
                        continue;
                } 
                putchar(ch);

                if (ch == '\n') { /* end of string => write 0, return */
                        buf[index] = '\0';
                        return (count_t) index;
                }
                buf[index++] = ch;
        }
        return (count_t) index;
}

/** Get character from device & echo it to screen */
uint8_t getc(chardev_t *chardev)
{
        uint8_t ch;

        ch = _getc(chardev);
        putchar(ch);
        return ch;
}

void putchar(char c)
{
        if ((klog_stored > 0) && (stdout->op->write)) {
                /* Print charaters stored in kernel log */
                index_t i;
                for (i = klog_len - klog_stored; i < klog_len; i++)
                        stdout->op->write(stdout, klog[(klog_start + i) % KLOG_SIZE]);
                klog_stored = 0;
        }
        
        /* Store character in the cyclic kernel log */
        klog[(klog_start + klog_len) % KLOG_SIZE] = c;
        if (klog_len < KLOG_SIZE)
                klog_len++;
        else
                klog_start = (klog_start + 1) % KLOG_SIZE;
        
        if (stdout->op->write)
                stdout->op->write(stdout, c);
        else {
                /* The character is just in the kernel log */
                if (klog_stored < klog_len)
                        klog_stored++;
        }
}

/** @}
 */