| Line 1... |
Line 1... |
|
;
|
|
; dskser.s -- disk made available by serial interface
|
|
;
|
|
|
|
;***************************************************************
|
|
|
|
.export dskcapser ; determine disk capacity
|
|
.export dskioser ; do disk I/O
|
|
|
|
.import ser1in
|
|
.import ser1out
|
|
.import ser1inchk
|
|
.import puts
|
|
|
|
; constants for communication with disk server
|
|
.set SYN,0x16 ; to initiate the three-way handshake
|
|
.set ACK,0x06 ; acknowledgement for handshake
|
|
.set RESULT_OK,0x00 ; server successfully executed cmd
|
|
; everything else means error
|
|
|
|
.set WAIT_DELAY,800000 ; count for delay loop
|
|
|
|
;***************************************************************
|
|
|
|
.code
|
|
.align 4
|
|
|
|
dskcapser:
|
|
sub $29,$29,16
|
|
stw $16,$29,0
|
|
stw $17,$29,4
|
|
stw $18,$29,8
|
|
stw $31,$29,12
|
|
add $4,$0,trymsg ; say what we are doing
|
|
jal puts
|
|
add $18,$0,$0 ; capacity == 0 if disk not present
|
|
add $16,$0,10 ; 10 tries to get a connection
|
|
handshake1:
|
|
sub $16,$16,1
|
|
add $4,$0,SYN
|
|
jal ser1out ; send SYN
|
|
add $17,$0,WAIT_DELAY ; wait for ACK
|
|
handshake2:
|
|
sub $17,$17,1
|
|
jal ser1inchk
|
|
bne $2,$0,handshake3
|
|
bne $17,$0,handshake2
|
|
add $4,$0,timeoutmsg
|
|
jal puts
|
|
bne $16,$0,handshake1
|
|
add $4,$0,frustratedmsg
|
|
jal puts
|
|
j dskcapx
|
|
handshake3:
|
|
jal ser1in
|
|
add $8,$0,ACK
|
|
bne $2,$8,dskcapx
|
|
; we got an ACK so we return it
|
|
add $4,$0,ACK
|
|
jal ser1out
|
|
|
|
; ask it for its capacity
|
|
add $4,$0,'c'
|
|
jal ser1out ; request
|
|
jal ser1in ; first byte of response
|
|
bne $2,$0,dskcapx ; exit if error
|
|
|
|
; all is well and the server will give us the capacity
|
|
add $16,$0,4 ; 4 bytes to read
|
|
dskcap1:
|
|
sll $18,$18,8
|
|
jal ser1in
|
|
or $18,$18,$2 ; most significant byte first
|
|
sub $16,$16,1
|
|
bne $16,$0,dskcap1
|
|
|
|
; return value is in $18
|
|
dskcapx:
|
|
add $2,$0,$18
|
|
ldw $16,$29,0
|
|
ldw $17,$29,4
|
|
ldw $18,$29,8
|
|
ldw $31,$29,12
|
|
add $29,$29,16
|
|
jr $31
|
|
|
|
.data
|
|
.align 4
|
|
|
|
trymsg:
|
|
.byte "Trying to connect to disk server..."
|
|
.byte 0x0A, 0
|
|
|
|
timeoutmsg:
|
|
.byte "Request timed out..."
|
|
.byte 0x0A, 0
|
|
|
|
frustratedmsg:
|
|
.byte "Unable to establish connection to disk server."
|
|
.byte 0x0A, 0
|
|
|
|
.code
|
|
.align 4
|
|
|
|
dskioser:
|
|
sub $29,$29,24
|
|
stw $16,$29,0
|
|
stw $17,$29,4
|
|
stw $18,$29,8
|
|
stw $19,$29,12
|
|
stw $20,$29,16
|
|
stw $31,$29,20
|
|
add $16,$0,$4 ; command
|
|
add $17,$0,$5 ; start at sector
|
|
add $8,$0,0xc0000000
|
|
or $18,$8,$6 ; memory address (logicalized)
|
|
add $19,$0,$7 ; number of sectors
|
|
|
|
; switch over command
|
|
add $8,$0,'r'
|
|
beq $8,$16,dskior ; read
|
|
add $8,$0,'w'
|
|
beq $8,$16,dskiow ; write
|
|
; unknown command
|
|
add $2,$0,1 ; value != 0 signifies error
|
|
j dskiox
|
|
|
|
; read from disk
|
|
dskior:
|
|
dskior1: ; loop over number of sectors
|
|
beq $19,$0,dskiorsuc ; successful return
|
|
sub $19,$19,1
|
|
; read a sector
|
|
add $4,$0,'r'
|
|
jal ser1out
|
|
; send sector number
|
|
add $20,$0,32 ; 4 bytes
|
|
dskior2:
|
|
sub $20,$20,8
|
|
slr $4,$17,$20
|
|
and $4,$4,0xff
|
|
jal ser1out
|
|
bne $20,$0,dskior2
|
|
add $17,$17,1
|
|
; get answer
|
|
jal ser1in
|
|
bne $2,$0,dskiox ; $2 != 0 so we use it as return code
|
|
; read data
|
|
add $20,$0,512
|
|
dskior3:
|
|
sub $20,$20,1
|
|
jal ser1in
|
|
stb $2,$18,0
|
|
add $18,$18,1
|
|
bne $20,$0,dskior3
|
|
j dskior1
|
|
dskiorsuc:
|
|
add $2,$0,$0
|
|
j dskiox
|
|
|
|
; write to disk
|
|
dskiow:
|
|
dskiow1: ; loop over number of sectors
|
|
beq $19,$0,dskiowsuc ; successful return
|
|
sub $19,$19,1
|
|
; write a sector
|
|
add $4,$0,'w'
|
|
jal ser1out
|
|
; send sector number
|
|
add $20,$0,32 ; 4 bytes
|
|
dskiow2:
|
|
sub $20,$20,8
|
|
slr $4,$17,$20
|
|
and $4,$4,0xff
|
|
jal ser1out
|
|
bne $20,$0,dskiow2
|
|
add $17,$17,1
|
|
; write data
|
|
add $20,$0,512
|
|
dskiow3:
|
|
sub $20,$20,1
|
|
ldbu $4,$18,0
|
|
jal ser1out
|
|
add $18,$18,1
|
|
bne $20,$0,dskiow3
|
|
; get answer
|
|
jal ser1in
|
|
bne $2,$0,dskiox
|
|
j dskiow1
|
|
dskiowsuc:
|
|
add $2,$0,$0
|
|
dskiox:
|
|
ldw $16,$29,0
|
|
ldw $17,$29,4
|
|
ldw $18,$29,8
|
|
ldw $19,$29,12
|
|
ldw $20,$29,16
|
|
ldw $31,$29,20
|
|
add $29,$29,24
|
|
jr $31
|
|
|
No newline at end of file
|
No newline at end of file
|
