NetBSD/sys/arch/x68k/stand/xxboot/chkfmt.s

149 lines
2.9 KiB
ArmAsm

|
| check FD format
|
| Written by Yasha (ITOH Yasufumi)
| This code is in the public domain
|
| $NetBSD: chkfmt.s,v 1.1 1998/09/01 20:02:34 itohy Exp $
/* FDC address */
#define FDC_STATUS 0xE94001 /* status register */
#define FDC_DATA 0xE94003 /* data register */
#define INT_STAT 0xE9C001 /* interrupt control */
#define INT_FDC_BIT 2
/* Status Register */
#define NE7ST_CB_BIT 4 /* FDC busy */
#define NE7ST_DIO_BIT 6 /* data input/output */
#define NE7ST_RQM_BIT 7 /* request for master */
/* FDC command */
#define NE7CMD_READID 0x4A /* READ ID */
|
| Read ID of all sectors in current track.
| This routine expects that motor on, drive selection
| and seek is already done.
|
| input: d0.b: 0 0 0 0 0 HD US1 US0 (binary)
| output: d0.l: min # sector (N C H R (2hex))
| d1.l: max # sector (N C H R (2hex))
| destroy:
| d0, d1
|
.text
.even
.globl check_fd_format
check_fd_format:
moveml d2-d7/a1-a3,sp@-
moveb d0,d6 | head, drive
lea FDC_STATUS:l,a1
lea a1@(FDC_DATA-FDC_STATUS),a2 | FDC_DATA
lea a2@(INT_STAT-FDC_DATA),a3 | INT_STAT
movew sr,sp@-
oriw #0x0700,sr | keep out interrupts
bclr #INT_FDC_BIT,a3@ | disable FDC interrupt
jbsr read_id_sub
jne exit_check_format
movel d3,d2 | first sector
movel d3,d0 | sector min
movel d3,d1 | sector max
loop_read_id:
jbsr read_id_sub
jne exit_check_format
cmpl d0,d3
jcc sector_not_min
movel d3,d0
sector_not_min:
cmpl d3,d1
jcc sector_not_max
movel d3,d1
sector_not_max:
cmpl d2,d3
jne loop_read_id
exit_check_format:
bset #INT_FDC_BIT,a3@ | enable FDC interrupt
movew a7@+,sr
tstl d7
moveml a7@+,d2-d7/a1-a3
jne _err_read_id
rts
|
| input: d6.b: 0 0 0 0 0 HD US1 US0 (binary)
| a1: FDC status addr
| a2: FDC data addr
| interrupt must be disabled
| output: d3.l: sector information: N C H R (2hex)
| d7.l: status (nonzero if error)
| Z flag: true if no error, false if error
| destroy:
| d3-d5, d7
|
read_id_sub:
| wait for FDC ready
fdc_wait_ready:
btst #NE7ST_CB_BIT,a1@
jne fdc_wait_ready
| send READ ID command
moveq #NE7CMD_READID,d4
jbsr fdc_send_command
moveb d6,d4 | X X X X X HD US1 US0 (binary)
jbsr fdc_send_command
| receive data
moveq #2,d4
jbsr fdc_read_bytes
movel d3,d7 | d7: FDC status: X ST0 ST1 ST2 (2hex)
moveq #3,d4
jbsr fdc_read_bytes | d3: sector info: C H R N (2hex)
rorl #8,d3 | d3: sector info: N C H R (2hex)
andil #0x00f8ffff,d7 | check status (must be zero)
rts
|
| send one byte of command
|
fdc_send_command:
jbsr fdc_wait_rqm
jne fdc_send_command
moveb d4,a2@
rts
|
| receive d4:w+1 bytes from FDC
|
fdc_read_bytes:
asll #8,d3
fdc_read_loop:
jbsr fdc_wait_rqm
jeq fdc_read_loop
moveb a2@,d3
dbra d4,fdc_read_bytes
rts
fdc_wait_rqm:
moveb a1@,d5
| btst #NE7ST_RQM_BIT,d5
| jeq fdc_wait_rqm
jpl fdc_wait_rqm | NE7ST_RQM_BIT = 7: sign bit
btst #NE7ST_DIO_BIT,d5
rts
|
| error
|
_err_read_id:
BOOT_ERROR("READ ID failed")