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include <mach.h>
include <fset.h>
include "vt.h"
# READHEADER -- Read header info from the input.
int procedure readheader(inputfd, hbuf, selfbuf)
int inputfd # input file discriptor
pointer hbuf # header data input buffer pointer (short, SZ_VTHDR)
bool selfbuf # flag to tell if we should do our own buffering
int numchars
pointer sp, tempbuf
int read()
errchk read
begin
call smark (sp)
call salloc (tempbuf, 100, TY_SHORT)
# If we are reading from tape and buffering for ourselves then
# do a large read and see how many chars we get. If too few or
# too many give an error. Otherwise just read the correct number
# of chars.
if (selfbuf) {
iferr (numchars = read (inputfd, Mems[tempbuf],
10000*SZB_SHORT/SZB_CHAR)) {
call fseti (inputfd, F_VALIDATE, SZ_VTHDR*SZB_SHORT/SZB_CHAR)
call printf ("Error reading header.\n")
numchars = read (inputfd, Mems[tempbuf],
SZ_VTHDR*SZB_SHORT/SZB_CHAR)
}
if (numchars < 10 || numchars >= 100) {
call error (0, "error reading header")
return (numchars)
}
call amovs (Mems[tempbuf], Mems[hbuf], SZ_VTHDR*SZB_SHORT/SZB_CHAR)
} else {
iferr (numchars = read (inputfd, Mems[hbuf],
SZ_VTHDR*SZB_SHORT/SZB_CHAR)) {
call fseti (inputfd, F_VALIDATE, SZ_VTHDR*SZB_SHORT/SZB_CHAR)
call printf ("Error reading header.\n")
numchars = read (inputfd, Mems[tempbuf],
SZ_VTHDR*SZB_SHORT/SZB_CHAR)
}
if (numchars < SZ_VTHDR*SZB_SHORT/SZB_CHAR) {
call error (0, "eof encountered when reading header")
return (0)
}
}
if (BYTE_SWAP2 == YES)
call bswap2 (Mems[hbuf], 1, Mems[hbuf], 1, SZ_VTHDR*SZB_SHORT)
call sfree (sp)
return (SZ_VTHDR*SZB_SHORT/SZB_CHAR)
end
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