jcs.org
Example program for the Cidco MailStation Z80 computer
wifi: Preserve upper 4 status bits on CONTROL_PORT
Only the bottom 4 bits of this port are control bits for the
parallel port. The upper 4 are status bits for power, so if we're
constantly clearing them in our WiFiStation routines, we won't get
proper readings of the power button when it's pressed.
+15
-5
+15
-5
lib/wifi.s
+15
-5
lib/wifi.s
···
27
27
.equ CONTROL_DIR_IN, #0
28
28
29
29
.equ CONTROL_PORT, #0x9
30
+
.equ CONTROL_STATUS_MASK, #0xf0
30
31
.equ CONTROL_STROBE_BIT, #0
31
32
.equ CONTROL_STROBE, #(1 << CONTROL_STROBE_BIT)
32
33
.equ CONTROL_LINEFEED_BIT, #1
···
48
49
; lower control lines
49
50
ld a, #CONTROL_DIR_OUT
50
51
out (#CONTROL_DIR), a
51
-
xor a
52
+
in a, (#CONTROL_PORT)
53
+
and #CONTROL_STATUS_MASK
52
54
out (#CONTROL_PORT), a
53
55
ret
54
56
···
75
77
ld c, 4(ix) ; char to send
76
78
ld a, #DATA_DIR_OUT
77
79
out (#DATA_DIR), a ; we're sending out
78
-
ld a, #CONTROL_STROBE
80
+
in a, (#CONTROL_PORT)
81
+
and #CONTROL_STATUS_MASK
82
+
set #CONTROL_STROBE_BIT, a
79
83
out (#CONTROL_PORT), a ; raise strobe
80
84
ld de, #0xffff
81
85
wait_for_ack:
···
94
98
ld a, c
95
99
out (#DATA_PORT), a ; write data
96
100
xor a
101
+
in a, (#CONTROL_PORT)
102
+
and #CONTROL_STATUS_MASK
97
103
out (#CONTROL_PORT), a ; lower strobe
98
104
ld de, #0xffff
99
105
wait_for_final_ack:
···
114
120
ld hl, #0 ; return 0
115
121
ret
116
122
abort_send:
117
-
xor a
123
+
in a, (#CONTROL_PORT)
124
+
and #CONTROL_STATUS_MASK
118
125
out (#CONTROL_PORT), a ; lower strobe
119
126
pop de
120
127
pop bc
···
137
144
jr nz, recv_done
138
145
ld a, #DATA_DIR_IN
139
146
out (#DATA_DIR), a ; we're reading in
140
-
ld a, #CONTROL_LINEFEED ; raise linefeed
147
+
in a, (#CONTROL_PORT)
148
+
and #CONTROL_STATUS_MASK
149
+
set #CONTROL_LINEFEED_BIT, a ; raise linefeed
141
150
out (#CONTROL_PORT), a
142
151
ld de, #0xffff
143
152
wait_for_busy_ack:
···
157
166
ld h, #0
158
167
ld l, a
159
168
raise_lf:
160
-
xor a
169
+
in a, (#CONTROL_PORT)
170
+
and #CONTROL_STATUS_MASK
161
171
out (#CONTROL_PORT), a ; lower linefeed
162
172
recv_done:
163
173
pop de