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/* -*- asm -*- ----------------------------------------------------------- *
 *   
 *   Copyright 2013 H. Peter Anvin - All Rights Reserved
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *   
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *   
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

#include "v9fs.h"

	.code16
	.section ".rtext","ax"

/* ------------------------------------------------------------------------- *
 *  acc_always
 *
 *  Always accept an incoming request.
 * ------------------------------------------------------------------------- */

GPROC(acc_always)
	clc
	retw
END(acc_always)

/* ------------------------------------------------------------------------- *
 *  acc_file
 *
 *  Check drive in the System File Table
 * ------------------------------------------------------------------------- */

GPROC(acc_file)
	movw F_DI,%si
	movw F_ES,%fs
	addw $SFT_DEVINFO,%si		/* Byte 5 in SFT entry = drive */
	/* fall through */
END(acc_file)

	/*
	 * Available for multiple users of a modified drive number
	 * at %fs:(%si)	- specifically a one-based drive number where
	 * bit 6 is expected to be set for a conforming redirector.
	 */
LPROC(acc_drive_common)
	movb %fs:(%si),%al		/* Device info word (low half) */
	andb $0x5f,%al			/* Drive number + conforming bit (6) */
	cmpb drive_letter,%al
	jne acc_fail
	/* CF = 0 if equal */
	retw
END(acc_drive_common)

/* ------------------------------------------------------------------------- *
 *  acc_findnext
 * ------------------------------------------------------------------------- */

GPROC(acc_findnext)
	lfsw dos_sdafn,%si
	addw $SDN_SEARCHDATA,%si	/* First byte in srcrec = drive no */
	jmp acc_drive_common
END(acc_findnext)

/* ------------------------------------------------------------------------- *
 *  acc_never
 *
 *  This is never for us; either we don't support it or we don't do
 *  anything with it anyway.
 * ------------------------------------------------------------------------- */

GPROC(acc_never)
acc_fail:				/* Used as common tail */
	stc
	retw
END(acc_never)

	.globl fxn_unknown
fxn_unknown	= acc_never

/* ------------------------------------------------------------------------- *
 *  acc_cds
 *
 *  The SDA contains a copy of the CDS for the current access - use it to
 *  determine if this is for us.
 * ------------------------------------------------------------------------- */

GPROC(acc_cds)
	lfsw dos_cdsptr,%si
	lfsw %fs:(%si),%si
	/* Fall through */
END(acc_cds)
LPROC(acc_cds_common)
	cmpw $CDS_MAGIC,%fs:CDS_USERVAL(%si)	/* Our magic? */
	jne acc_fail
	movb drive_letter,%al
	cmpb %al,%fs:(CDS_PATH+0)(%si)		/* Our drive letter? */
	jne acc_fail
	cmpw $0x5c3a,%fs:(CDS_PATH+1)(%si)	/* Path starts with X:\? */
	jne acc_fail
	/* XXX: check for a character device */
	/* CF = 0 if equal */
	retw
END(acc_cds)

/* ------------------------------------------------------------------------- *
 *  acc_cds_esdi
 *
 *  ES:DI contains a pointer to the CDS
 * ------------------------------------------------------------------------- */

GPROC(acc_cds_esdi)
	movw F_DI,%si
	movw F_ES,%fs
	jmp acc_cds_common
END(acc_cds_esdi)

/* ------------------------------------------------------------------------- *
 *  acc_qualify
 * ------------------------------------------------------------------------- */

GPROC(acc_qualify)
	movw F_SI,%si
	movw F_DS,%fs
	jmp acc_drive_common
END(acc_qualify)