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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <syserr.h>
include <plio.h>
# PL_COMPRESS -- Compress the line list buffer to eliminate any unusable
# space, as is generated when mask lines are modified and the old line lists
# are freed. The compress operation may move the line lists about, possibly
# changing the line offsets.
procedure pl_compress (pl)
pointer pl #I mask descriptor
pointer n_bp, o_lp, n_lp, op
int nwords, r_len, b_len, i
errchk malloc, mfree, syserr
begin
# Redundant calls are ignored.
if (PL_LLNUPDATES(pl) <= 0)
return
# Return if there was a prior error with plalloc.
if (PL_LLBP(pl) == NULL)
call syserr (SYS_PLBADMASK)
# Count the total space in the active line lists.
nwords = 0
for (i=0; i < PL_LLOP(pl); i=i+b_len) {
o_lp = Ref (pl, i)
b_len = LP_BLEN(o_lp)
if (b_len <= 0 || b_len > PL_LLOP(pl))
call syserr (SYS_PLBADMASK)
if (i == PL_EMPTYLINE || LP_NREF(o_lp) > 0)
nwords = nwords + LP_LEN(o_lp)
}
# Verify that the free space accounting is correct.
if (nwords != (PL_LLOP(pl) - PL_LLFREE(pl)))
call eprintf ("Warning: PL_LLFREE inconsistent (recoverable)\n")
# Allocate a new buffer large enough to hold the compressed line list.
call malloc (n_bp, nwords, TY_SHORT)
# Copy the active line lists to the new buffer; as each line is
# copied, overwrite a couple words of the old line list with the
# new offset of the line.
op = 0
for (i=0; i < PL_LLOP(pl); i=i+b_len) {
o_lp = Ref (pl, i)
b_len = LP_BLEN(o_lp)
if (b_len <= 0 || b_len > PL_LLOP(pl))
call syserr (SYS_PLBADMASK)
if (i == PL_EMPTYLINE || LP_NREF(o_lp) > 0) {
n_lp = n_bp + op
r_len = LP_LEN(o_lp)
# The following should not be possible, barring a bug.
if (op + r_len > nwords)
call fatal (pl, "pl_compress: llbuf overflow")
call amovs (Mems[o_lp], Mems[n_lp], r_len)
LP_NREFS(o_lp) = op / I_SHIFT
LP_SETBLEN(o_lp, mod (op, I_SHIFT))
LP_SETBLEN(n_lp, r_len)
op = op + r_len
}
}
# Fix up the line index by accessing the tag word in the old line list
# in the old buffer to get the line list offset in the new buffer.
do i = 1, PL_NLP(pl) {
o_lp = Ref (pl, PL_LP(pl,i))
PL_LP(pl,i) = LP_NREF(o_lp) * I_SHIFT + LP_BLEN(o_lp)
}
# Deallocate the old buffer and install the new one.
call mfree (PL_LLBP(pl), TY_SHORT)
PL_LLBP(pl) = n_bp
PL_LLOP(pl) = op
PL_LLLEN(pl) = nwords
PL_LLFREE(pl) = 0
PL_LLNUPDATES(pl) = 0
end
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