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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <mach.h>
include "m75.h"
include "iis.h"
# ZRDM75 -- Initiate an asynchronous read of data from the IIS. Note that
# the zwrm75 procedure is called to write the header for data reads, as well
# as writes. Hence we should be called only after the header has been saved
# in the channel descriptor by ZWRM75, leaving the channel in state DATA_READ.
# Our task is to translate and output the header, read the M75 data block, and
# return the data block to the user after performing any transformations
# necessary to make it look like M70fdata.
procedure zrdm75 (ifcb, buf, nbytes_buf, offset)
int ifcb # pointer to channel descriptor passed as int
short buf[ARB] # data array
int nbytes_buf # nbytes of data in buffer
long offset # not used
pointer fcb
short m70[LEN_IISHDR]
short m75[LEN_IISHDR]
int nbytes, status, sum, i
int xferid, subunit, xreg, yreg
int and(), or(), not()
begin
fcb = ifcb
nbytes = nbytes_buf
if (FCB_STATE(fcb) != DATA_READ) {
FCB_STATUS(fcb) = ERR
return
}
# Retrieve the M70 header from the channel descriptor.
call amovs (FCB_IISHDR(fcb), m70, LEN_IISHDR)
xferid = XFERID(m70)
subunit = SUBUNIT(m70)
xreg = XREG(m70)
yreg = YREG(m70)
# Start with a copy of the header for the M75, but turn off those bits
# in the transfer id which the M70 knows nothing about and hence could
# not have set.
call amovs (m70, m75, LEN_IISHDR)
XFERID(m75) = and (xferid,
not (BYTEORDER+PMA+ACCELERATE+REPEAT+PAGEMODE))
# Translate the remaining fields of the header as necessary for each
# subunit.
switch (and (subunit, 77B)) {
case REFRESH:
if (and (xreg, M70_ADVXONTC) != 0)
subunit = or (subunit, M75_ADVXONTC)
if (and (xreg, M70_ADVXONYOV) != 0)
subunit = or (subunit, M75_ADVXONYOV)
if (and (yreg, M70_ADVYONTC) != 0)
subunit = or (subunit, M75_ADVYONTC)
if (and (yreg, M70_ADVYONXOV) != 0)
subunit = or (subunit, M75_ADVYONXOV)
SUBUNIT(m75) = subunit
XREG(m75) = and (xreg, IIS_XDIM-1)
YREG(m75) = and (yreg, IIS_YDIM-1)
case LUT:
XREG(m75) = and (xreg, 1777B)
YREG(m75) = 0
case OFM:
XREG(m75) = and (xreg, 1777B)
YREG(m75) = 0
# The M70 OFM lookup table is 10 bits deep, whereas the M75 table
# is only 8 bits deep, so scale the 8 bit M75 values up to 10 bits.
do i = 1, nbytes_buf / (SZB_CHAR * SZ_SHORT)
buf[i] = buf[i] * 4
case FEEDBACK:
subunit = COMMAND + FEEDBACK
SUBUNIT(m75) = subunit
XREG(m75) = 0
YREG(m75) = 0
case GRAPHICS:
XREG(m75) = and (xreg, 777B)
TREG(m75) = 0 # ??
case CURSOR:
XREG(m75) = and (xreg, 7777B)
YREG(m75) = 0
case M70_SCROLL:
SUBUNIT(m75) = SCROLLZOOM
XREG(m75) = and (xreg, 3B)
YREG(m75) = 0
ZREG(m75) = ALLBITPL
TREG(m75) = SCROLL + WRAP
case M70_ZOOM:
SUBUNIT(m75) = SCROLLZOOM
THINGCT(m75) = 2
nbytes = 2 * (SZ_SHORT * SZB_CHAR)
XREG(m75) = and (xreg, 3B)
YREG(m75) = 0
ZREG(m75) = ALLBITPL
TREG(m75) = ZOOM
}
# Compute the checksum for the new header.
CHECKSUM(m75) = 1
if (THINGCT(m75) > 0)
THINGCT(m75) = -THINGCT(m75)
sum = 0
do i = 1, LEN_IISHDR
sum = sum + m75[i]
CHECKSUM(m75) = -sum
# Output the header.
call zzwrii (fcb, m75, SZB_IISHDR, offset)
call zwtm75 (ifcb, status)
if (status == ERR) {
FCB_STATUS(fcb) = ERR
return
}
# Read the data block.
if (nbytes > 0) {
call zzrdii (fcb, buf, nbytes, offset)
call zwtm75 (ifcb, status)
if (status <= 0) {
FCB_STATUS(fcb) = ERR
return
}
}
# Perform any transformations on the data just read necessary to
# convert it into M70 format. If the number of bytes read is
# different than that expected by the M70, be sure to set the
# expected count in the channel descriptor for the next ZWTM75.
if (and (subunit, 77B) == ZOOM) {
FCB_NBYTES(fcb) = 3 * (SZ_SHORT * SZB_CHAR)
FCB_STATUS(fcb) = IIS_INACTIVE
buf[3] = mod (int(buf[2]), 10000B)
buf[2] = mod (int(buf[1]), 10000B)
buf[1] = buf[1] / 10000B
}
FCB_STATE(fcb) = READY
end
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