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Annotation of Gnu-Mach/i386/dos/dos_read.c, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Copyright (c) 1995-1994 The University of Utah and
        !             3:  * the Computer Systems Laboratory at the University of Utah (CSL).
        !             4:  * All rights reserved.
        !             5:  *
        !             6:  * Permission to use, copy, modify and distribute this software is hereby
        !             7:  * granted provided that (1) source code retains these copyright, permission,
        !             8:  * and disclaimer notices, and (2) redistributions including binaries
        !             9:  * reproduce the notices in supporting documentation, and (3) all advertising
        !            10:  * materials mentioning features or use of this software display the following
        !            11:  * acknowledgement: ``This product includes software developed by the
        !            12:  * Computer Systems Laboratory at the University of Utah.''
        !            13:  *
        !            14:  * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
        !            15:  * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
        !            16:  * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            17:  *
        !            18:  * CSL requests users of this software to return to [email protected] any
        !            19:  * improvements that they make and grant CSL redistribution rights.
        !            20:  *
        !            21:  *      Author: Bryan Ford, University of Utah CSL
        !            22:  */
        !            23: 
        !            24: #include <unistd.h>
        !            25: #include <errno.h>
        !            26: 
        !            27: #include "dos_io.h"
        !            28: #include "vm_param.h"
        !            29: 
        !            30: int dos_read(dos_fd_t fd, void *buf, vm_size_t size, vm_size_t *out_actual)
        !            31: {
        !            32:        int err;
        !            33:        int actual = 0;
        !            34:        struct real_call_data real_call_data;
        !            35:        vm_offset_t dos_buf_phys = (vm_offset_t)kvtophys(dos_buf);
        !            36: 
        !            37:        assert(dos_buf); assert(dos_buf_phys);
        !            38:        assert(dos_buf_phys < 0x100000);
        !            39: 
        !            40:        dos_init_rcd(&real_call_data);
        !            41: 
        !            42:        while (size > 0)
        !            43:        {
        !            44:                int little_size = size;
        !            45:                int little_actual;
        !            46: 
        !            47:                if (little_size > DOS_BUF_SIZE)
        !            48:                        little_size = DOS_BUF_SIZE;
        !            49: 
        !            50:                real_call_data.eax = 0x3f00;
        !            51:                real_call_data.ebx = fd;
        !            52:                real_call_data.ecx = little_size;
        !            53:                real_call_data.ds = dos_buf_phys >> 4;
        !            54:                real_call_data.edx = dos_buf_phys & 15;
        !            55:                real_int(0x21, &real_call_data);
        !            56:                if (err = dos_check_err(&real_call_data))
        !            57:                        return err;
        !            58:                little_actual = real_call_data.eax & 0xffff;
        !            59:                assert(little_actual <= little_size);
        !            60: 
        !            61:                /* XXX don't copy if buf is <1MB */
        !            62:                memcpy(buf, dos_buf, little_actual);
        !            63: 
        !            64:                buf += little_actual;
        !            65:                size -= little_actual;
        !            66:                actual += little_actual;
        !            67: 
        !            68:                if (little_actual < little_size)
        !            69:                        break;
        !            70:        }
        !            71: 
        !            72:        *out_actual = actual;
        !            73:        return 0;
        !            74: }
        !            75: 

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