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Annotation of 43BSDReno/lib/csu.i386/crt0.c, revision 1.1

1.1     ! root        1: /*-
        !             2:  * Copyright (c) 1990 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software contributed to Berkeley by
        !             6:  * William Jolitz.
        !             7:  *
        !             8:  * Redistribution and use in source and binary forms are permitted
        !             9:  * provided that: (1) source distributions retain this entire copyright
        !            10:  * notice and comment, and (2) distributions including binaries display
        !            11:  * the following acknowledgement:  ``This product includes software
        !            12:  * developed by the University of California, Berkeley and its contributors''
        !            13:  * in the documentation or other materials provided with the distribution
        !            14:  * and in all advertising materials mentioning features or use of this
        !            15:  * software. Neither the name of the University nor the names of its
        !            16:  * contributors may be used to endorse or promote products derived
        !            17:  * from this software without specific prior written permission.
        !            18:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            19:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            20:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            21:  */
        !            22: 
        !            23: #ifndef lint
        !            24: static char sccsid[] = "@(#)crt0.c     5.2 (Berkeley) 5/14/90";
        !            25: #endif /* not lint */
        !            26: 
        !            27: /*
        !            28:  *     C start up routine.
        !            29:  *     Robert Henry, UCB, 20 Oct 81
        !            30:  *
        !            31:  *     We make the following (true) assumption:
        !            32:  *     1) The only register variable that we can trust is ebp,
        !            33:  *     which points to the base of the kernel calling frame.
        !            34:  */
        !            35: 
        !            36: char **environ = (char **)0;
        !            37: static int fd;
        !            38: 
        !            39: asm("#define _start start");
        !            40: asm("#define _eprol eprol");
        !            41: asm("  .text");
        !            42: asm("  .long 0xc000c000");
        !            43: extern unsigned char   etext;
        !            44: extern unsigned char   eprol;
        !            45: start()
        !            46: {
        !            47:        struct kframe {
        !            48:                int     kargc;
        !            49:                char    *kargv[1];      /* size depends on kargc */
        !            50:                char    kargstr[1];     /* size varies */
        !            51:                char    kenvstr[1];     /* size varies */
        !            52:        };
        !            53:        /*
        !            54:         *      ALL REGISTER VARIABLES!!!
        !            55:         */
        !            56:        register struct kframe *kfp;    /* r10 */
        !            57:        register char **targv;
        !            58:        register char **argv;
        !            59:        extern int errno;
        !            60: 
        !            61: #ifdef lint
        !            62:        kfp = 0;
        !            63:        initcode = initcode = 0;
        !            64: #else not lint
        !            65:        asm("   lea     4(%ebp),%ebx"); /* catch it quick */
        !            66: #endif not lint
        !            67:        for (argv = targv = &kfp->kargv[0]; *targv++; /* void */)
        !            68:                /* void */ ;
        !            69:        if (targv >= (char **)(*argv))
        !            70:                --targv;
        !            71:        environ = targv;
        !            72: asm("eprol:");
        !            73: 
        !            74: #ifdef paranoid
        !            75:        /*
        !            76:         * The standard I/O library assumes that file descriptors 0, 1, and 2
        !            77:         * are open. If one of these descriptors is closed prior to the start 
        !            78:         * of the process, I/O gets very confused. To avoid this problem, we
        !            79:         * insure that the first three file descriptors are open before calling
        !            80:         * main(). Normally this is undefined, as it adds two unnecessary
        !            81:         * system calls.
        !            82:         */
        !            83:        do      {
        !            84:                fd = open("/dev/null", 2);
        !            85:        } while (fd >= 0 && fd < 3);
        !            86:        close(fd);
        !            87: #endif paranoid
        !            88: 
        !            89: #ifdef MCRT0
        !            90:        monstartup(&eprol, &etext);
        !            91: #endif MCRT0
        !            92:        errno = 0;
        !            93:        exit(main(kfp->kargc, argv, environ));
        !            94: }
        !            95: asm("#undef _start");
        !            96: asm("#undef _eprol");
        !            97: 
        !            98: #ifdef MCRT0
        !            99: /*ARGSUSED*/
        !           100: exit(code)
        !           101:        register int code;      /* r11 */
        !           102: {
        !           103:        monitor(0);
        !           104:        _cleanup();
        !           105:        asm("   pushl   8(bp)") ;
        !           106:        asm("   movl $1,%eax");
        !           107:        asm("   .byte 0x9a; .long 0; .word 0");
        !           108: }
        !           109: #endif MCRT0
        !           110: 
        !           111: #ifdef CRT0
        !           112: /*
        !           113:  * null mcount and moncontrol,
        !           114:  * just in case some routine is compiled for profiling
        !           115:  */
        !           116: moncontrol(val)
        !           117:        int val;
        !           118: {
        !           119: 
        !           120: }
        !           121: asm("  .globl  mcount");
        !           122: asm("mcount:   ret");
        !           123: #endif CRT0

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