1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <mach.h>
include "m75.h"
include "iis.h"
# ZWRM75 -- Initiate an asynchronous write to the IIS. We are called to
# output the header of all instructions sent to the IIS. There are 3 types
# of instructions; those which consist only of a header write, those which
# consist of a header write followed by a data write, and those which
# consist of a header write followed by a data read. Translation of an M70
# instruction into an M75 instruction may involve moving information between
# the header and data block, hence we must save the headers of the read and
# write instructions until the data has been read or written. The STATE
# variable in the channel descriptor is used to keep track of the instruction
# processing state.
procedure zwrm75 (ifcb, buf, nbytes, offset)
int ifcb # pointer to channel descriptor passed as int
char buf[ARB] # input buffer
int nbytes # number of bytes to write
long offset # not used for this device
pointer fcb
int xferid, and()
begin
fcb = ifcb
if (FCB_STATE(fcb) == READY) {
# Start a new instruction.
if (nbytes != SZB_IISHDR) {
FCB_STATUS(fcb) = ERR
return
}
# Save the M70 header in the descriptor.
call amovs (buf, FCB_IISHDR(fcb), LEN_IISHDR)
xferid = XFERID(buf)
# Determine the state for the new instruction.
if (THINGCT(buf) == 0)
FCB_STATE(fcb) = READY
else if (and (xferid, IREAD) != 0)
FCB_STATE(fcb) = DATA_READ
else
FCB_STATE(fcb) = DATA_WRITE
# If the new state is READY, no data read or write is needed,
# so just translate and output the header.
if (FCB_STATE(fcb) == READY)
call m75put (fcb, buf, nbytes, offset)
else {
# Set up a channel status as if we had just written the new
# header, so that the next ZWTM75 will not return an error.
FCB_STATUS(fcb) = IIS_INACTIVE
FCB_NBYTES(fcb) = SZB_IISHDR
}
} else if (FCB_STATE(fcb) == DATA_WRITE) {
# This is the second zwrm75 call for a hdr+data output
# instruction.
call m75put (fcb, buf, nbytes, offset)
FCB_STATE(fcb) = READY
} else {
# ZRDM75 should have been called, set error on the channel.
FCB_STATUS(fcb) = ERR
}
end
|
