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Annotation of coherent/b/kernel/io.386/console.c, revision 1.1

1.1     ! root        1: /* $Header: /src386/kernel/io.386/RCS/console.c,v 1.3 92/08/28 09:02:49 bin Exp Locker: bin $ */
        !             2: /*
        !             3:  * Tiny console driver.
        !             4:  * 8086/8088 Coherent, IBM PC.
        !             5:  *
        !             6:  * $Log:       console.c,v $
        !             7:  * Revision 1.3  92/08/28  09:02:49  bin
        !             8:  * update by hal for kernel 61
        !             9:  * 
        !            10:  * Revision 1.2  92/01/06  12:26:44  hal
        !            11:  * Compile with cc.mwc.
        !            12:  * 
        !            13:  * Revision 2.1        88/09/03  13:03:39      src
        !            14:  * *** empty log message ***
        !            15:  * 
        !            16:  * Revision 1.1        88/03/24  17:04:25      src
        !            17:  * Initial revision
        !            18:  * 
        !            19:  * 86/11/19    Allan Cornish           /usr/src/sys/i8086/drv/console.c
        !            20:  * putchar() initializes the (new) (IO).io_flag field to 0.
        !            21:  */
        !            22: #include <sys/coherent.h>
        !            23: #include <sys/inode.h>
        !            24: #include <sys/stat.h>
        !            25: #include <sys/con.h>
        !            26: #include <sys/io.h>
        !            27: 
        !            28: #define P_LEN 512      /* Keep about six full lines of characters.  */
        !            29: /*
        !            30:  * Stash messages in p_buf[] until we can print them.
        !            31:  * Note that p_buf[] can not be safely kalloc()'d because even
        !            32:  * those routines could generate printf()'s.
        !            33:  */
        !            34: static char    p_buf[P_LEN];
        !            35: static int     p_off;  /* Offset into p_buff.  */
        !            36: int ok_to_use_dev = 0; /* Can we use the console device yet?  */
        !            37: 
        !            38: int coninit = 0;
        !            39: dev_t condev = makedev(2,0);
        !            40: 
        !            41: putchar(c)
        !            42: int c;
        !            43: {
        !            44:        IO iob;
        !            45: 
        !            46: 
        !            47:        /*
        !            48:         * If we get a printf before the devices have been initialized,
        !            49:         * keep as many characters as we can until we can print them.
        !            50:         */
        !            51:        if (condev != makedev(2,0) && !ok_to_use_dev) {
        !            52:                if (p_off == P_LEN) {
        !            53:                        p_buf[P_LEN-1] = '*';   /* Mark an overrun.  */
        !            54:                } else {
        !            55:                        p_buf[p_off++] = c;     /* Stash the character.  */
        !            56:                }
        !            57:                return;
        !            58:        }
        !            59: 
        !            60:        if (coninit == 0) {
        !            61:                ++coninit;
        !            62:                dopen( condev, IPW, DFCHR );
        !            63:        }
        !            64: 
        !            65:        if (c == '\n')
        !            66:                putchar('\r');
        !            67: 
        !            68:        iob.io_seg  = IOSYS;
        !            69:        iob.io_ioc  = 1;
        !            70:        iob.io.vbase = &c;
        !            71:        iob.io_flag = 0;
        !            72:        dwrite( condev, &iob );
        !            73: } /* putchar() */
        !            74: 
        !            75: 
        !            76: /*
        !            77:  * putchar_init() is called from main() once devices have been
        !            78:  * initialized.  It marks the condev as usable, and then prints
        !            79:  * anything that has been stored away.
        !            80:  */
        !            81: putchar_init()
        !            82: {
        !            83:        int i;
        !            84: 
        !            85:        /* Mark condev as usable.  */
        !            86:        ok_to_use_dev = 1;
        !            87: 
        !            88:        /* nothing to do if CRT is console device */
        !            89:        if (condev == makedev(2,0))
        !            90:                return;
        !            91: 
        !            92:        /* Dump everything we've stored away.  */
        !            93:        for (i = 0; i < p_off; ++i) {
        !            94:                putchar(p_buf[i]);
        !            95:        }
        !            96:        
        !            97:        printf("\n-\n");
        !            98:        if ('*' == p_buf[P_LEN-1]) {
        !            99:                printf("\npb buffer overrun detected.\n");
        !           100:        }
        !           101: } /* putchar_init() */

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