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248 lines
4.6 KiB
ArmAsm
248 lines
4.6 KiB
ArmAsm
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/*
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* low-level functions for the SWIM floppy controller
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*
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* needs assembly language because is very timing dependent
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* this controller exists only on macintosh 680x0 based
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*
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* Copyright (C) 2004,2008 Laurent Vivier <Laurent@lvivier.info>
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*
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* based on Alastair Bridgewater SWIM analysis, 2001
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* based on netBSD IWM driver (c) 1997, 1998 Hauke Fath.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* 2004-08-21 (lv) - Initial implementation
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* 2008-11-05 (lv) - add get_swim_mode
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*/
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.equ write_data, 0x0000
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.equ write_mark, 0x0200
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.equ write_CRC, 0x0400
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.equ write_parameter,0x0600
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.equ write_phase, 0x0800
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.equ write_setup, 0x0a00
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.equ write_mode0, 0x0c00
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.equ write_mode1, 0x0e00
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.equ read_data, 0x1000
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.equ read_mark, 0x1200
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.equ read_error, 0x1400
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.equ read_parameter, 0x1600
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.equ read_phase, 0x1800
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.equ read_setup, 0x1a00
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.equ read_status, 0x1c00
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.equ read_handshake, 0x1e00
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.equ o_side, 0
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.equ o_track, 1
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.equ o_sector, 2
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.equ o_size, 3
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.equ o_crc0, 4
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.equ o_crc1, 5
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.equ seek_time, 30000
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.equ max_retry, 40
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.equ sector_size, 512
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.global swim_read_sector_header
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swim_read_sector_header:
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link %a6, #0
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moveml %d1-%d5/%a0-%a4,%sp@-
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movel %a6@(0x0c), %a4
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bsr mfm_read_addrmark
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moveml %sp@+, %d1-%d5/%a0-%a4
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unlk %a6
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rts
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sector_address_mark:
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.byte 0xa1, 0xa1, 0xa1, 0xfe
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sector_data_mark:
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.byte 0xa1, 0xa1, 0xa1, 0xfb
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mfm_read_addrmark:
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movel %a6@(0x08), %a3
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lea %a3@(read_handshake), %a2
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lea %a3@(read_mark), %a3
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moveq #-1, %d0
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movew #seek_time, %d2
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wait_header_init:
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tstb %a3@(read_error - read_mark)
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moveb #0x18, %a3@(write_mode0 - read_mark)
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moveb #0x01, %a3@(write_mode1 - read_mark)
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moveb #0x01, %a3@(write_mode0 - read_mark)
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tstb %a3@(read_error - read_mark)
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moveb #0x08, %a3@(write_mode1 - read_mark)
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lea sector_address_mark, %a0
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moveq #3, %d1
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wait_addr_mark_byte:
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tstb %a2@
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dbmi %d2, wait_addr_mark_byte
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bpl header_exit
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moveb %a3@, %d3
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cmpb %a0@+, %d3
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dbne %d1, wait_addr_mark_byte
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bne wait_header_init
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moveq #max_retry, %d2
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amark0: tstb %a2@
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dbmi %d2, amark0
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bpl signal_nonyb
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moveb %a3@, %a4@(o_track)
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moveq #max_retry, %d2
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amark1: tstb %a2@
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dbmi %d2, amark1
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bpl signal_nonyb
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moveb %a3@, %a4@(o_side)
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moveq #max_retry, %d2
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amark2: tstb %a2@
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dbmi %d2, amark2
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bpl signal_nonyb
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moveb %a3@, %a4@(o_sector)
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moveq #max_retry, %d2
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amark3: tstb %a2@
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dbmi %d2, amark3
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bpl signal_nonyb
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moveb %a3@, %a4@(o_size)
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moveq #max_retry, %d2
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crc0: tstb %a2@
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dbmi %d2, crc0
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bpl signal_nonyb
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moveb %a3@, %a4@(o_crc0)
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moveq #max_retry, %d2
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crc1: tstb %a2@
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dbmi %d2, crc1
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bpl signal_nonyb
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moveb %a3@, %a4@(o_crc1)
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tstb %a3@(read_error - read_mark)
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header_exit:
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moveq #0, %d0
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moveb #0x18, %a3@(write_mode0 - read_mark)
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rts
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signal_nonyb:
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moveq #-1, %d0
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moveb #0x18, %a3@(write_mode0 - read_mark)
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rts
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.global swim_read_sector_data
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swim_read_sector_data:
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link %a6, #0
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moveml %d1-%d5/%a0-%a5,%sp@-
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movel %a6@(0x0c), %a4
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bsr mfm_read_data
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moveml %sp@+, %d1-%d5/%a0-%a5
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unlk %a6
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rts
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mfm_read_data:
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movel %a6@(0x08), %a3
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lea %a3@(read_handshake), %a2
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lea %a3@(read_data), %a5
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lea %a3@(read_mark), %a3
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movew #seek_time, %d2
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wait_data_init:
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tstb %a3@(read_error - read_mark)
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moveb #0x18, %a3@(write_mode0 - read_mark)
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moveb #0x01, %a3@(write_mode1 - read_mark)
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moveb #0x01, %a3@(write_mode0 - read_mark)
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tstb %a3@(read_error - read_mark)
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moveb #0x08, %a3@(write_mode1 - read_mark)
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lea sector_data_mark, %a0
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moveq #3, %d1
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/* wait data address mark */
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wait_data_mark_byte:
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tstb %a2@
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dbmi %d2, wait_data_mark_byte
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bpl data_exit
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moveb %a3@, %d3
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cmpb %a0@+, %d3
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dbne %d1, wait_data_mark_byte
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bne wait_data_init
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/* read data */
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tstb %a3@(read_error - read_mark)
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movel #sector_size-1, %d4 /* sector size */
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read_new_data:
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movew #max_retry, %d2
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read_data_loop:
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moveb %a2@, %d5
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andb #0xc0, %d5
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dbne %d2, read_data_loop
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beq data_exit
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moveb %a5@, %a4@+
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andb #0x40, %d5
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dbne %d4, read_new_data
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beq exit_loop
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moveb %a5@, %a4@+
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dbra %d4, read_new_data
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exit_loop:
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/* read CRC */
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movew #max_retry, %d2
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data_crc0:
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tstb %a2@
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dbmi %d2, data_crc0
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bpl data_exit
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moveb %a3@, %d5
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moveq #max_retry, %d2
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data_crc1:
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tstb %a2@
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dbmi %d2, data_crc1
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bpl data_exit
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moveb %a3@, %d5
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tstb %a3@(read_error - read_mark)
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moveb #0x18, %a3@(write_mode0 - read_mark)
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/* return number of bytes read */
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movel #sector_size, %d0
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addw #1, %d4
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subl %d4, %d0
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rts
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data_exit:
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moveb #0x18, %a3@(write_mode0 - read_mark)
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moveq #-1, %d0
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rts
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